Incidence and Prognostic Impact of Amenorrhea During Adjuvant Therapy in High-Risk Premenopausal Breast Cancer: Analysis of a National Cance
http://www.100md.com
《临床肿瘤学》
the National Cancer Institute of Canada Clinical Trials Group, Queen's University
Clinical Research Centre, Kingston General Hospital, Kingston
Toronto Sunnybrook Regional Cancer Centre, Toronto
Juravinski Cancer Centre, Hamilton Health Sciences, Hamilton, Ontario
Tom Baker Cancer Centre, Calgary, Alberta, Canada
ABSTRACT
PURPOSE: To investigate the therapeutic impact of chemotherapy-induced amenorrhea in premenopausal patients with breast cancer.
PATIENTS AND METHODS: We conducted a retrospective cohort study of a National Cancer Institute of Canada Clinical Trials Group phase III trial involving premenopausal patients randomized to receive cyclophosphamide, methotrexate, and fluorouracil (CMF), versus intensive cyclophosphamide, epirubicin, and fluorouracil (CEF). The objectives of our study were to describe the incidence of amenorrhea at 6 and 12 months post-random assignment and to determine the association of amenorrhea with relapse-free and overall survival.
RESULTS: Data on 442 patients were used in our analyses. Despite the higher cumulative dose of cyclophosphamide in the CMF treatment arm, at 6 months post–random assignment, the rate of amenorrhea was higher in the CEF group (relative risk, 1.2; 95% CI, 1.0 to 1.3), with no difference at 12 months. In the receptor-positive subgroup, 6-month amenorrhea rates were not associated with prognosis. In contrast, amenorrhea at 12 months was significantly associated with relapse-free survival (hazard ratio, 0.51; 95% CI, 0.32 to 0.82; P = .005) and overall survival (hazard ratio, 0.40; 95% CI, 0.22 to 0.72; P = .002).
CONCLUSION: Late chemotherapy-induced amenorrhea seems to be associated with improved outcome in patients with premenopausal, receptor-positive breast cancer.
INTRODUCTION
The phenomenon of chemotherapy-related amenorrhea is well characterized in patients with premenopausal breast cancer, though the therapeutic relevance remains uncertain. Both chemotherapy and primary ovarian ablation (by surgical, radiation, or medical means) have demonstrated efficacy in premenopausal breast cancer patients,1-4 which suggests that the mechanism of action of chemotherapy may be two-fold: that of direct cytotoxicity against tumor cells and an indirect antitumor effect due to estrogen deprivation secondary to treatment-related ovarian failure. The fundamental question thus becomes: Is achievement of amenorrhea a desirable side effect of chemotherapy, or is it merely a surrogate marker of an effective antitumor dose of a particular agent/combination of agents?
We sought to describe our own experience with the phenomenon of chemotherapy-related amenorrhea by performing a retrospective cohort study using the database of a National Cancer Institute of Canada Clinical Trials Group phase III trial that evaluated the efficacy of intensive cyclophosphamide, epirubicin, and fluorouracil (CEF), versus the standard Bonadonna regimen of oral cyclophosphamide, methotrexate, and fluorouracil (CMF), in pre- and perimenopausal patients with node-positive breast cancer. Use of tamoxifen or other endocrine therapy was prohibited on study. This trial accrued patients from 1989 to 1993, and demonstrated a relapse-free and overall survival benefit for patients treated with the CEF regimen.5
The objectives of our study were: (1) to describe the incidence of chemotherapy-induced amenorrhea in patients treated with CEF and CMF at 6 months (completion of adjuvant therapy) and 12 months post-random assignment; and (2) to determine the association of amenorrhea with relapse-free and overall survival.
PATIENTS AND METHODS
Information for this study was retrieved from the MA.5 trial database, last updated April 5, 2002 (median follow-up, 8.8 years; range, 0.2 to 12.1 years).6 Patients eligible for this analysis were premenopausal with normal menses and known receptor status at the time of random assignment. Due to the time-dependent nature of development of amenorrhea, we further restricted inclusion criteria to those patients who completed the protocol-mandated six cycles of chemotherapy and remained disease-free for the first 12 months after random assignment. The definition of amenorrhea was identical to that used in the original protocol: cessation of menses for 3 consecutive months. Amenorrhea status at 6 and 12 months was obtained from the original case report forms since the data had been prospectively collected during study conduct. Six-month amenorrhea was defined as absence of menses for 3 consecutive months (ie, months 4 to 6). Similarly, patients with 12-month amenorrhea had no menses for the preceding 3 months. During conduct of the trial, at their clinic follow-up visits, patients were periodically asked about menstrual function based on their recollection; individual calendar logs of menstrual history were not mandated for this trial. Missing data on menstrual status were retrieved by mail-out surveys distributed to participating centers between September 2002 and March 20, 2003.
Fisher's exact test was used to compare amenorrhea rates between patient groups. Overall and relapse-free survival rates were compared by amenorrhea status at 6 and 12 months after enrollment on MA.5. Survival time was measured from 1 year post-random assignment. Kaplan-Meier curves were used to describe survival by amenorrhea status. The stratified Cox model was used to formally compare survival by amenorrhea status while controlling (stratifying) for age ( 39 years, 40-44 years, 45 years), number of positive nodes (1 to 3 v 4), tumor size (T1, T2, T3), and treatment arm (CEF v CMF). A similar model stratifying for age, number of positive nodes, tumor size, and receptor status was used to describe the treatment effect of CEF versus CMF in patients with and without amenorrhea at 1 year. The statistical significance of the difference in treatment effect between amenorrhea statuses was assessed by testing the interaction term in a model with predictor variables for treatment, amenorrhea status, and their interaction. The models provided hazard ratio estimates with asymptotic 95% CIs and Wald tests for comparing hazard ratios to unity. The proportional hazard assumption for amenorrhea status was verified by examining log-log survival curves and performing a goodness-of-fit test based on the Schoenfeld residuals.7 Time-dependent covariates were also used to test for an interaction between amenorrhea status and time. With the exception of the examination of treatment effect by 12-month amenorrhea status, all analyses were performed separately for patients with receptor-positive and receptor-negative tumors at baseline. Receptor status was defined using the dextran charcoal method, as in the original study. A classification of positive indicated estrogen receptor and/or progesterone receptor values of 10 fmol/mg cytosol protein. Negative status indicated that both were less than 10. All tests were two-sided, and SAS version 8.2 (SAS Institute, Cary, NC) was used for all analyses.
RESULTS
Seven hundred sixteen patients were randomly assigned between December 1989 and July 1993. Of these, 442 patients were eligible for our study. Reasons for exclusion from our study included: ineligibility for the original study (n = 6), not fitting the criteria for regular menses (eg, perimenopausal status or prior hysterectomy; n = 152), not completing six cycles of therapy (n = 17), relapse within 12 months (n = 42), and unknown receptor status (n = 57). Amenorrhea status was known at the 6-month time period in 405 patients (92% of those eligible) and at 12 months in 328 patients (74%; Fig 1). Amenorrhea status was known at both periods for 307 patients (69% of those eligible). Patient characteristics (age, chemotherapy, type of surgery, receptor status, number of involved nodes, T-stage) were similar at both time periods between subjects with known and unknown amenorrhea status (not shown). Although patients with an unknown status at 6 months were more likely to have an unknown status at 1 year (relative risk [RR], 1.8), the rate of unknown status at 1 year was very similar for patients who had a known positive compared with a known negative status at 6 months (25% v 24%). From the subset of 307 patients who had a known status at both time points, approximately 88% of those who were amenorrheic at 6 months remained so at 1 year. Approximately 41% of patients without amenorrhea at 6 months became amenorrheic by the 1-year assessment. The bulk of the data on menstrual status were abstracted from the original case report forms completed while patients were on the study. The results of the mail-out survey increased the percentage of available 6-month menstrual status data from 87% to 92%. For the 12-month amenorrhea status, this increased from to 55% to 74%.
The median age for the sample was 43.8 years (range, 23.4 to 55.2). Analysis of baseline characteristics (age, type of surgery, receptor status, number of involved nodes, T-stage) by 6-month and 12-month amenorrhea status was performed. As anticipated, at both time points, only age was significantly associated with menstrual status (P < .0001). Ninety percent of patients older than 45 years were amenorrheic at 1 year, compared with 41% for those 39 years or younger.
Patient characteristics were well balanced across the two treatment arms for the following characteristics: age, surgery type, receptor status, number of positive nodes, and pathologic T-stage (data not shown). The mean cumulative dose of cyclophosphamide was higher in the CMF arm compared with CEF (7,816 mg/m2 [range, 3,575 to 9,032] v 5,386 mg/m2 [range, 3,550 to 7,000]).
The 6-month and 12-month amenorrhea rates by treatment arm and age are presented in Table 1 for the receptor-positive and -negative cohorts. In the receptor-positive cohort, the 6-month amenorrhea rate was significantly higher in the CEF arm compared with the CMF arm (CEF/CMF RR, 1.2; 95% CI, 1.0 to 1.4; P = .03) with the difference most evident in the youngest age group (age < 39 years RR, 2.2; 95% CI, 1.3 to 3.8). By 1 year, there was no significant difference between the treatment arms (CEF/CMF RR, 1.1; 95% CI, 0.92 to 1.2; P = .5) in terms of amenorrhea. Similarly, data from the receptor-negative cohort at 6 months showed a trend toward a higher incidence of amenorrhea in the CEF arm, but this did not reach statistical significance at any point.
The association of 6- and 12-month amenorrhea status with disease-free and overall survival in receptor-positive and -negative patients is presented in Table 2. Cessation of menses at 6 months did not seem to have a significant effect on relapse-free or overall survival. In contrast, the presence of amenorrhea at 12 months was significantly associated with increased relapse-free survival (hazard ratio [HR], 0.51; 95% CI, 0.32 to 0.82; P = .005) and overall survival (HR, 0.40; 95% CI, 0.22 to 0.72; P = .002) in the receptor-positive subgroup, with nonsignificant trends toward improved survival seen in the receptor-negative group. The Kaplan-Meier curves by 12-month amenorrhea status are shown in Figures 2 (disease-free survival) and 3 (overall survival) for the receptor-positive patients. Model diagnostics did not reveal any gross departures from the proportional hazards assumption other than the demonstration that the hazard ratio of overall survival by 12-month amenorrhea status inverted at about 1 year of follow-up, but remained roughly constant after that time (Fig 3).
As a means of exploring the hypothesis that chemotherapy exerts both a direct cytoxic as well as an indirect endocrine effect, we calculated the hazard ratio for disease-free survival between the treatment arms (CEF/CMF) in those patients who achieved and did not achieve amenorrhea at 12 months. Patients with receptor-negative and receptor-positive disease were included in these analyses. In both amenorrhea groups, there was a non-statistically significant trend toward superior survival, favoring the CEF arm, with the bigger effect seen in the nonamenorrheic population: 0.59 (95% CI, 0.28 to 1.2; patients without amenorrhea) and 0.86 (95% CI, 0.56 to 1.3; patients with amenorrhea). No interaction between the treatment effect and amenorrhea status was suggested by the stratified Cox model (P = .27), though the study was not adequately powered to test for such an interaction. The same model (without interaction term) demonstrated a trend favoring the CEF arm after controlling for 12-month amenorrhea status (HR, 0.76; 95% CI, 0.53 to 1.1).
DISCUSSION
One of the primary aims of this analysis was to describe and compare the rates of amenorrhea in the two chemotherapy arms. Somewhat surprisingly, the rate was higher in the CEF arm at 6 months, but similar by 12 months, despite the lower cumulative dose of cyclophosphamide in the CEF arm compared to CMF. This suggests the existence of a threshold effect of ovarian toxicity for a specific dose of cyclophosphamide, or that, similar to findings of others,8 epirubicin (and the anthracyclines in general) may be gonadotoxic.
We also sought to examine the effect of amenorrhea at 6 and 12 months on relapse-free and overall survival. Our results indicate that menstrual status at 6 months had little association with outcome, with a trend toward worsened survival in the receptor-negative cohort. The explanation for this is unclear and may be a spurious finding due to small numbers, or, alternatively, may indicate a relatively "sicker patient" who was more prone to develop early amenorrhea compared with those who continued to menstruate. In contrast, amenorrhea at 12 months had a statistically significant association with relapse-free survival and overall survival in the receptor-positive subgroup, with a trend toward improved outcome in the receptor-negative patients. The biologically plausible former observation suggests a therapeutic significance to cessation of menses. In the receptor-negative group of patients, a plausible explanation to this finding is that amenorrhea is in fact a surrogate marker for effective doses of chemotherapy.
The limitations of our study are mainly methodological (ie, retrospective analyses in subgroups of patients from a previously reported randomized trial). This is countered somewhat by the relatively large sample size included in our analyses and the integrity of the data since most of it was collected in a prospective and standardized fashion. Other limitations relate to uncertainties regarding the phenomenon of amenorrhea such as definition (timing of onset and duration) and its validity as a marker of ovarian failure since measurement of serum gonadotropins was not mandated during the original study. In addition, the biochemical method of determining receptor status and the resulting categorization of patients into receptor-negative and -positive groups in our study differs from the current use of immunohistochemistry to classify patients. Presumably, some of the patients classified as receptor-negative using the former method would be reclassified as positive using the latter method, and expected to derive some benefit from endocrine manipulation. Finally, the finding that late amenorrhea (12 months) may be more beneficial than early amenorrhea (6 months) may be influenced by the availability of data. Compliance with reporting, although relatively high in general, declined from the 6- to the 12-month period. Thus, the differences in outcome between the two points may have been due to real effects of early versus late amenorrhea, or due in part to other unmeasured factors in the different cohorts who had menstrual status assessable at the two time points.
The prognostic importance of chemotherapy-induced amenorrhea has been demonstrated by others,8-19 though this has not been a consistent finding.20-23 To further address the issue, Del Mastro et al24 performed a review of 13 studies involving 3,929 subjects treated with CMF-based regimens. With follow-up ranging from 3 to 20 years, a statistically significant association was found between the development of chemotherapy-related amenorrhea and disease-free survival in the majority of groups included in the analysis. Overall survival was statistically significantly associated with amenorrhea in three of five studies reviewed.
Our analysis and the bulk of the evidence to date suggest that the development of treatment-induced amenorrhea may improve outcome in premenopausal breast cancer patients, especially in those with receptor positive disease. The relative contribution of chemical castration to the overall therapeutic effect of chemotherapy in young women remains an intriguing question. The higher incidence (although statistically significant at 6 months only) and earlier onset of amenorrhea in the CEF group raises the possibility that the endocrine effect may be greater in this chemotherapy regimen compared to CMF. In the MA.5 trial endocrine therapy with tamoxifen after completion of chemotherapy was not allowed. Hence the results of the analysis may not be generalizable to current practice. Furthermore, the relevance of chemotherapy-induced amenorrhea in current practice is difficult to ascertain especially in light of the widespread use of tamoxifen and the availability of alternate means of ovarian suppression such as GnRH analogs. Ongoing phase III studies examining the role of ovarian suppression, such as SOFT (IBCSG-24-02: Suppression of Ovarian Function Plus Either Tamoxifen or Exemestane Compared With Tamoxifen Alone in Treating Premenopausal Women With Hormone-Responsive Breast Cancer), TEXT (IBCSG-25-02: Triptorelin Plus Exemestane Compared With Triptorelin Plus Tamoxifen in Treating Women With Hormone-Responsive Breast Cancer), and PERCHE (IBCSG-26-02: Suppression of Ovarian Function and Either Tamoxifen or Exemestane With or Without Chemotherapy in Treating Premenopausal Women With Hormone-Responsive Breast Cancer), will yield important information regarding the role of ovarian suppression in the treatment of premenopausal breast cancer.
In conclusion, amenorrhea is a common occurrence in premenopausal patients receiving adjuvant cyclophosphamide-based chemotherapy and seems to be associated with prognosis. Presence of amenorrhea at 12 months after commencement of therapy may be more important in this regard than its presence at 6 months. Furthermore, the magnification of association in those patients with receptor positive tumors suggests that cessation of menses may have therapeutic significance, though it cannot be concluded that ovarian failure is the sole mechanism of action of chemotherapy. Finally, the impact of anthracyclines such as epirubicin on ovarian function deserves further study.
Authors' Disclosures of Potential Conflicts of Interest
Although all authors completed the disclosure declaration, the following authors or their immediate family members indicated a financial interest. No conflict exists for drugs or devices used in a study if they are not being evaluated as part of the investigation. For a detailed description of the disclosure categories, or for more information about ASCO’s conflict of interest policy, please refer to the Author Disclosure Declaration and the Disclosures of Potential Conflicts of Interest section in Information for Contributors.
NOTES
Authors' disclosures of potential conflicts of interest are found at the end of this article.
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Early Breast Cancer Trialists' Collaborative Group: Ovarian ablation in early breast cancer: Overview of the randomised trials. Lancet 348:1189-1196, 1996
Early Breast Cancer Trialists' Collaborative Group: Polychemotherapy for early breast cancer: An overview of the randomised trials. Lancet 352:930-942, 1998
Jonat W, Kaufmann M, Sauerbrei W, et al: Goserelin versus cyclophosphamide, methotrexate, and fluorouracil as adjuvant therapy in premenopausal patients with node-positive breast cancer: The Zoladex Early Breast Cancer Research Association study. J Clin Oncol 20:4628-4635, 2002
Jakesz R, Hausmaninger H, Kubista E, et al: Randomized adjuvant trial of tamoxifen and goserelin versus cyclophosphamide, methotrexate, and fluorouracil: Evidence for the superiority of treatment with endocrine blockade in premenopausal patients with hormone-responsive breast cancer—Austrian Breast and Colorectal Cancer Study Group Trial 5. J Clin Oncol 20:4621-4627, 2002
Levine MN, Bramwell VH, Pritchard KI, et al: Randomized trial of intensive cyclophosphamide, epirubicin, and fluorouracil chemotherapy compared with cyclpohosphamide, methotrezate, and fluorouracil in premenopausal women with node-positive breast cancer. J Clin Oncol 16:2651-2658, 1998
Pritchard KI, Levine MN, Bramwell VHC, et al: A randomized trial comparing CEF to CMF in premenopausal women with node positive breast cancer: Update of NCIC CTG MA.5. Breast Cancer Res Treat 76:S33, 2002
Schoenfeld D: Partial residuals for the proportional hazards regression model. Biometrika 69:239-241, 1982
Borde F, Chapelle-Marcillac I, Fumoleau P, et al: Role of chemo-induced amenorrhea in premenopausal, node-positive, operable breast cancer patients: 9-year follow-up results of French Adjuvant Study Group (FASG) data base. Breast Cancer Res Treat 82:S30, 2003
Ludwig Breast Cancer Study Group: A randomized trial of adjuvant chemotherapy with or without prednisone in premenopausal patients with metastases in one to three axillary lymph nodes. Cancer Res 45:4454-4459, 1985
Brickner H, Rose C, Rank R, et al: Evidence of a castration: Mediated effect of adjuvant cytotoxic chemotherapy in premenopausal breast cancer. J Clin Oncol 5:1771-1778, 1987
Beex LVAM, MacKenzie MA, Raemaekers JMM, et al: Adjuvant chemotherapy in premenopausal patients with primary breast cancer: Relation to drug-induced amenorrhoea, age and the progesterone receptor status of the tumour. Eur J Cancer Clin Oncol 24:719-721, 1988
Tormey DC, Gray R, Gilchrist K, et al: Adjuvant chemohormonal therapy with cyclophosphamide, methotrexate, 5-fluorouracil, and prednisone (CMFP) or CMFP plus tamoxifen compared with cmf for premenopausal breast cancer patients. Cancer 65:200-206, 1990
Richards MA, O'Reilly SM, Howell A, et al: Adjuvant cyclophosphamide, methotrexate, and fluorouracil in patients with axillary node positive breast cancer: An update of the Guy's/Manchester Trial. J Clin Oncol 8:2032-2039, 1990
Goldhirsch A, Gelber RD, Castiglione M: The magnitude of endocrine effects of adjuvant chemotherapy for premenopausal breast cancer patients. Ann Oncol 1:183-188, 1990
Bianco AR, Del Mastro L, Gallo C, et al: Prognostic role of amenorrhea induced by adjuvant chemotherpay in premenopausal patients with early breast cancer. Br J Cancer 63:799-803, 1991
Tormey DC, Gray R, Abeloff MD, et al: Adjuvant therapy with a doxorubicin regimen and long-term tamoxifen in premenopausal breast cancer patients: An Eastern Cooperative Oncology Group Trial. J Clin Oncol 10:1848-1856, 1992
Reyno LM, Levine MN, Skingley P, et al: Chemotherapy induced amenorrhoea in a randomized trial of adjuvant chemotherapy duration in breast cancer. Eur J Cancer 29A:21-23, 1993
Pagani O, O'Neill A, Castiglione M, et al: Prognostic impact of amenorrhoea after adjuvant chemotherapy in premenopausal breast cancer patients with axillary node involvement: Results of the International Breast Cancer Study Group (IBCSG) Trial VI. Eur J Cancer 34:632-640, 1998
Poikonen P, Saarto T, Elomaa I, et al: Prognostic effect of amenorrhoea and elevated serum gonadotropin levels induced by adjuvant chemotherapy in premenopausal node-positive breast cancer patients. Eur J Cancer 36:43-48, 2000
Rubens RD, Hayward JL, Knight RK, et al: Controlled trial of adjuvant chemotherapy with melphalan for breast cancer. Lancet 1:839-843, 1983
International Breast Cancer Study Group: Late effects of adjuvant oophorectomy and chemotherapy upon premenopausal breast cancer patients. Ann Oncol 1:30-35, 1990
Campora E, Pronzato P, Amoroso D, et al: Prognostic factors in node positive primary breast cancer patients treated with adjuvant CMF. Anticancer Res 12:1555-1558, 1992
Bonadonna G, Valagussa P, Moliterni A, et al: Adjuvant cyclophosphamide, methotrexate, and fluorouracil in node-positive breast cancer: The results of 20 years of follow-up. N Engl J Med 332:901-906, 1995
Del Masto L, Venturini M, Sertoli MR, et al: Amenorrhea induced by adjuvant chemotherapy in early breast cancer patients: Prognostic role and clinical implications. Breast Cancer Res Treat 43:183-190, 1997(Wendy R. Parulekar, Andre)
Clinical Research Centre, Kingston General Hospital, Kingston
Toronto Sunnybrook Regional Cancer Centre, Toronto
Juravinski Cancer Centre, Hamilton Health Sciences, Hamilton, Ontario
Tom Baker Cancer Centre, Calgary, Alberta, Canada
ABSTRACT
PURPOSE: To investigate the therapeutic impact of chemotherapy-induced amenorrhea in premenopausal patients with breast cancer.
PATIENTS AND METHODS: We conducted a retrospective cohort study of a National Cancer Institute of Canada Clinical Trials Group phase III trial involving premenopausal patients randomized to receive cyclophosphamide, methotrexate, and fluorouracil (CMF), versus intensive cyclophosphamide, epirubicin, and fluorouracil (CEF). The objectives of our study were to describe the incidence of amenorrhea at 6 and 12 months post-random assignment and to determine the association of amenorrhea with relapse-free and overall survival.
RESULTS: Data on 442 patients were used in our analyses. Despite the higher cumulative dose of cyclophosphamide in the CMF treatment arm, at 6 months post–random assignment, the rate of amenorrhea was higher in the CEF group (relative risk, 1.2; 95% CI, 1.0 to 1.3), with no difference at 12 months. In the receptor-positive subgroup, 6-month amenorrhea rates were not associated with prognosis. In contrast, amenorrhea at 12 months was significantly associated with relapse-free survival (hazard ratio, 0.51; 95% CI, 0.32 to 0.82; P = .005) and overall survival (hazard ratio, 0.40; 95% CI, 0.22 to 0.72; P = .002).
CONCLUSION: Late chemotherapy-induced amenorrhea seems to be associated with improved outcome in patients with premenopausal, receptor-positive breast cancer.
INTRODUCTION
The phenomenon of chemotherapy-related amenorrhea is well characterized in patients with premenopausal breast cancer, though the therapeutic relevance remains uncertain. Both chemotherapy and primary ovarian ablation (by surgical, radiation, or medical means) have demonstrated efficacy in premenopausal breast cancer patients,1-4 which suggests that the mechanism of action of chemotherapy may be two-fold: that of direct cytotoxicity against tumor cells and an indirect antitumor effect due to estrogen deprivation secondary to treatment-related ovarian failure. The fundamental question thus becomes: Is achievement of amenorrhea a desirable side effect of chemotherapy, or is it merely a surrogate marker of an effective antitumor dose of a particular agent/combination of agents?
We sought to describe our own experience with the phenomenon of chemotherapy-related amenorrhea by performing a retrospective cohort study using the database of a National Cancer Institute of Canada Clinical Trials Group phase III trial that evaluated the efficacy of intensive cyclophosphamide, epirubicin, and fluorouracil (CEF), versus the standard Bonadonna regimen of oral cyclophosphamide, methotrexate, and fluorouracil (CMF), in pre- and perimenopausal patients with node-positive breast cancer. Use of tamoxifen or other endocrine therapy was prohibited on study. This trial accrued patients from 1989 to 1993, and demonstrated a relapse-free and overall survival benefit for patients treated with the CEF regimen.5
The objectives of our study were: (1) to describe the incidence of chemotherapy-induced amenorrhea in patients treated with CEF and CMF at 6 months (completion of adjuvant therapy) and 12 months post-random assignment; and (2) to determine the association of amenorrhea with relapse-free and overall survival.
PATIENTS AND METHODS
Information for this study was retrieved from the MA.5 trial database, last updated April 5, 2002 (median follow-up, 8.8 years; range, 0.2 to 12.1 years).6 Patients eligible for this analysis were premenopausal with normal menses and known receptor status at the time of random assignment. Due to the time-dependent nature of development of amenorrhea, we further restricted inclusion criteria to those patients who completed the protocol-mandated six cycles of chemotherapy and remained disease-free for the first 12 months after random assignment. The definition of amenorrhea was identical to that used in the original protocol: cessation of menses for 3 consecutive months. Amenorrhea status at 6 and 12 months was obtained from the original case report forms since the data had been prospectively collected during study conduct. Six-month amenorrhea was defined as absence of menses for 3 consecutive months (ie, months 4 to 6). Similarly, patients with 12-month amenorrhea had no menses for the preceding 3 months. During conduct of the trial, at their clinic follow-up visits, patients were periodically asked about menstrual function based on their recollection; individual calendar logs of menstrual history were not mandated for this trial. Missing data on menstrual status were retrieved by mail-out surveys distributed to participating centers between September 2002 and March 20, 2003.
Fisher's exact test was used to compare amenorrhea rates between patient groups. Overall and relapse-free survival rates were compared by amenorrhea status at 6 and 12 months after enrollment on MA.5. Survival time was measured from 1 year post-random assignment. Kaplan-Meier curves were used to describe survival by amenorrhea status. The stratified Cox model was used to formally compare survival by amenorrhea status while controlling (stratifying) for age ( 39 years, 40-44 years, 45 years), number of positive nodes (1 to 3 v 4), tumor size (T1, T2, T3), and treatment arm (CEF v CMF). A similar model stratifying for age, number of positive nodes, tumor size, and receptor status was used to describe the treatment effect of CEF versus CMF in patients with and without amenorrhea at 1 year. The statistical significance of the difference in treatment effect between amenorrhea statuses was assessed by testing the interaction term in a model with predictor variables for treatment, amenorrhea status, and their interaction. The models provided hazard ratio estimates with asymptotic 95% CIs and Wald tests for comparing hazard ratios to unity. The proportional hazard assumption for amenorrhea status was verified by examining log-log survival curves and performing a goodness-of-fit test based on the Schoenfeld residuals.7 Time-dependent covariates were also used to test for an interaction between amenorrhea status and time. With the exception of the examination of treatment effect by 12-month amenorrhea status, all analyses were performed separately for patients with receptor-positive and receptor-negative tumors at baseline. Receptor status was defined using the dextran charcoal method, as in the original study. A classification of positive indicated estrogen receptor and/or progesterone receptor values of 10 fmol/mg cytosol protein. Negative status indicated that both were less than 10. All tests were two-sided, and SAS version 8.2 (SAS Institute, Cary, NC) was used for all analyses.
RESULTS
Seven hundred sixteen patients were randomly assigned between December 1989 and July 1993. Of these, 442 patients were eligible for our study. Reasons for exclusion from our study included: ineligibility for the original study (n = 6), not fitting the criteria for regular menses (eg, perimenopausal status or prior hysterectomy; n = 152), not completing six cycles of therapy (n = 17), relapse within 12 months (n = 42), and unknown receptor status (n = 57). Amenorrhea status was known at the 6-month time period in 405 patients (92% of those eligible) and at 12 months in 328 patients (74%; Fig 1). Amenorrhea status was known at both periods for 307 patients (69% of those eligible). Patient characteristics (age, chemotherapy, type of surgery, receptor status, number of involved nodes, T-stage) were similar at both time periods between subjects with known and unknown amenorrhea status (not shown). Although patients with an unknown status at 6 months were more likely to have an unknown status at 1 year (relative risk [RR], 1.8), the rate of unknown status at 1 year was very similar for patients who had a known positive compared with a known negative status at 6 months (25% v 24%). From the subset of 307 patients who had a known status at both time points, approximately 88% of those who were amenorrheic at 6 months remained so at 1 year. Approximately 41% of patients without amenorrhea at 6 months became amenorrheic by the 1-year assessment. The bulk of the data on menstrual status were abstracted from the original case report forms completed while patients were on the study. The results of the mail-out survey increased the percentage of available 6-month menstrual status data from 87% to 92%. For the 12-month amenorrhea status, this increased from to 55% to 74%.
The median age for the sample was 43.8 years (range, 23.4 to 55.2). Analysis of baseline characteristics (age, type of surgery, receptor status, number of involved nodes, T-stage) by 6-month and 12-month amenorrhea status was performed. As anticipated, at both time points, only age was significantly associated with menstrual status (P < .0001). Ninety percent of patients older than 45 years were amenorrheic at 1 year, compared with 41% for those 39 years or younger.
Patient characteristics were well balanced across the two treatment arms for the following characteristics: age, surgery type, receptor status, number of positive nodes, and pathologic T-stage (data not shown). The mean cumulative dose of cyclophosphamide was higher in the CMF arm compared with CEF (7,816 mg/m2 [range, 3,575 to 9,032] v 5,386 mg/m2 [range, 3,550 to 7,000]).
The 6-month and 12-month amenorrhea rates by treatment arm and age are presented in Table 1 for the receptor-positive and -negative cohorts. In the receptor-positive cohort, the 6-month amenorrhea rate was significantly higher in the CEF arm compared with the CMF arm (CEF/CMF RR, 1.2; 95% CI, 1.0 to 1.4; P = .03) with the difference most evident in the youngest age group (age < 39 years RR, 2.2; 95% CI, 1.3 to 3.8). By 1 year, there was no significant difference between the treatment arms (CEF/CMF RR, 1.1; 95% CI, 0.92 to 1.2; P = .5) in terms of amenorrhea. Similarly, data from the receptor-negative cohort at 6 months showed a trend toward a higher incidence of amenorrhea in the CEF arm, but this did not reach statistical significance at any point.
The association of 6- and 12-month amenorrhea status with disease-free and overall survival in receptor-positive and -negative patients is presented in Table 2. Cessation of menses at 6 months did not seem to have a significant effect on relapse-free or overall survival. In contrast, the presence of amenorrhea at 12 months was significantly associated with increased relapse-free survival (hazard ratio [HR], 0.51; 95% CI, 0.32 to 0.82; P = .005) and overall survival (HR, 0.40; 95% CI, 0.22 to 0.72; P = .002) in the receptor-positive subgroup, with nonsignificant trends toward improved survival seen in the receptor-negative group. The Kaplan-Meier curves by 12-month amenorrhea status are shown in Figures 2 (disease-free survival) and 3 (overall survival) for the receptor-positive patients. Model diagnostics did not reveal any gross departures from the proportional hazards assumption other than the demonstration that the hazard ratio of overall survival by 12-month amenorrhea status inverted at about 1 year of follow-up, but remained roughly constant after that time (Fig 3).
As a means of exploring the hypothesis that chemotherapy exerts both a direct cytoxic as well as an indirect endocrine effect, we calculated the hazard ratio for disease-free survival between the treatment arms (CEF/CMF) in those patients who achieved and did not achieve amenorrhea at 12 months. Patients with receptor-negative and receptor-positive disease were included in these analyses. In both amenorrhea groups, there was a non-statistically significant trend toward superior survival, favoring the CEF arm, with the bigger effect seen in the nonamenorrheic population: 0.59 (95% CI, 0.28 to 1.2; patients without amenorrhea) and 0.86 (95% CI, 0.56 to 1.3; patients with amenorrhea). No interaction between the treatment effect and amenorrhea status was suggested by the stratified Cox model (P = .27), though the study was not adequately powered to test for such an interaction. The same model (without interaction term) demonstrated a trend favoring the CEF arm after controlling for 12-month amenorrhea status (HR, 0.76; 95% CI, 0.53 to 1.1).
DISCUSSION
One of the primary aims of this analysis was to describe and compare the rates of amenorrhea in the two chemotherapy arms. Somewhat surprisingly, the rate was higher in the CEF arm at 6 months, but similar by 12 months, despite the lower cumulative dose of cyclophosphamide in the CEF arm compared to CMF. This suggests the existence of a threshold effect of ovarian toxicity for a specific dose of cyclophosphamide, or that, similar to findings of others,8 epirubicin (and the anthracyclines in general) may be gonadotoxic.
We also sought to examine the effect of amenorrhea at 6 and 12 months on relapse-free and overall survival. Our results indicate that menstrual status at 6 months had little association with outcome, with a trend toward worsened survival in the receptor-negative cohort. The explanation for this is unclear and may be a spurious finding due to small numbers, or, alternatively, may indicate a relatively "sicker patient" who was more prone to develop early amenorrhea compared with those who continued to menstruate. In contrast, amenorrhea at 12 months had a statistically significant association with relapse-free survival and overall survival in the receptor-positive subgroup, with a trend toward improved outcome in the receptor-negative patients. The biologically plausible former observation suggests a therapeutic significance to cessation of menses. In the receptor-negative group of patients, a plausible explanation to this finding is that amenorrhea is in fact a surrogate marker for effective doses of chemotherapy.
The limitations of our study are mainly methodological (ie, retrospective analyses in subgroups of patients from a previously reported randomized trial). This is countered somewhat by the relatively large sample size included in our analyses and the integrity of the data since most of it was collected in a prospective and standardized fashion. Other limitations relate to uncertainties regarding the phenomenon of amenorrhea such as definition (timing of onset and duration) and its validity as a marker of ovarian failure since measurement of serum gonadotropins was not mandated during the original study. In addition, the biochemical method of determining receptor status and the resulting categorization of patients into receptor-negative and -positive groups in our study differs from the current use of immunohistochemistry to classify patients. Presumably, some of the patients classified as receptor-negative using the former method would be reclassified as positive using the latter method, and expected to derive some benefit from endocrine manipulation. Finally, the finding that late amenorrhea (12 months) may be more beneficial than early amenorrhea (6 months) may be influenced by the availability of data. Compliance with reporting, although relatively high in general, declined from the 6- to the 12-month period. Thus, the differences in outcome between the two points may have been due to real effects of early versus late amenorrhea, or due in part to other unmeasured factors in the different cohorts who had menstrual status assessable at the two time points.
The prognostic importance of chemotherapy-induced amenorrhea has been demonstrated by others,8-19 though this has not been a consistent finding.20-23 To further address the issue, Del Mastro et al24 performed a review of 13 studies involving 3,929 subjects treated with CMF-based regimens. With follow-up ranging from 3 to 20 years, a statistically significant association was found between the development of chemotherapy-related amenorrhea and disease-free survival in the majority of groups included in the analysis. Overall survival was statistically significantly associated with amenorrhea in three of five studies reviewed.
Our analysis and the bulk of the evidence to date suggest that the development of treatment-induced amenorrhea may improve outcome in premenopausal breast cancer patients, especially in those with receptor positive disease. The relative contribution of chemical castration to the overall therapeutic effect of chemotherapy in young women remains an intriguing question. The higher incidence (although statistically significant at 6 months only) and earlier onset of amenorrhea in the CEF group raises the possibility that the endocrine effect may be greater in this chemotherapy regimen compared to CMF. In the MA.5 trial endocrine therapy with tamoxifen after completion of chemotherapy was not allowed. Hence the results of the analysis may not be generalizable to current practice. Furthermore, the relevance of chemotherapy-induced amenorrhea in current practice is difficult to ascertain especially in light of the widespread use of tamoxifen and the availability of alternate means of ovarian suppression such as GnRH analogs. Ongoing phase III studies examining the role of ovarian suppression, such as SOFT (IBCSG-24-02: Suppression of Ovarian Function Plus Either Tamoxifen or Exemestane Compared With Tamoxifen Alone in Treating Premenopausal Women With Hormone-Responsive Breast Cancer), TEXT (IBCSG-25-02: Triptorelin Plus Exemestane Compared With Triptorelin Plus Tamoxifen in Treating Women With Hormone-Responsive Breast Cancer), and PERCHE (IBCSG-26-02: Suppression of Ovarian Function and Either Tamoxifen or Exemestane With or Without Chemotherapy in Treating Premenopausal Women With Hormone-Responsive Breast Cancer), will yield important information regarding the role of ovarian suppression in the treatment of premenopausal breast cancer.
In conclusion, amenorrhea is a common occurrence in premenopausal patients receiving adjuvant cyclophosphamide-based chemotherapy and seems to be associated with prognosis. Presence of amenorrhea at 12 months after commencement of therapy may be more important in this regard than its presence at 6 months. Furthermore, the magnification of association in those patients with receptor positive tumors suggests that cessation of menses may have therapeutic significance, though it cannot be concluded that ovarian failure is the sole mechanism of action of chemotherapy. Finally, the impact of anthracyclines such as epirubicin on ovarian function deserves further study.
Authors' Disclosures of Potential Conflicts of Interest
Although all authors completed the disclosure declaration, the following authors or their immediate family members indicated a financial interest. No conflict exists for drugs or devices used in a study if they are not being evaluated as part of the investigation. For a detailed description of the disclosure categories, or for more information about ASCO’s conflict of interest policy, please refer to the Author Disclosure Declaration and the Disclosures of Potential Conflicts of Interest section in Information for Contributors.
NOTES
Authors' disclosures of potential conflicts of interest are found at the end of this article.
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