Testicular cancer has increased in many populations worldwide
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《英国医生杂志》
The number of cases of testicular cancer has increased by an average of 60% over 25 years in 21 populations across five continents, according to new research.
But the researchers, from the US National Cancer Institute, found big differences, with some rates 10 times higher than others. Why this increase has occurred and what is responsible remain unclear, say the researchers.
Although the incidence of cancer of the testis has risen markedly in many Western populations over the past half century, it has not been clear whether rates in other populations have also increased. In the research, which was published online on 9 February in the International Journal of Cancer (Wiley InterScience, www3.interscience.wiley.com, doi: 10.1002/ijc.20931), the authors examined the incidence of cancer of the testis over the period 1973 to 1997 as reported in 21 registries in countries in America, Asia, Africa, Europe, and Oceania.
The results show that the incidence rose between 1973 and 1997 in most populations, although the increases were highest among populations of European ancestry. The age adjusted incidence for 1993-7was highest in Denmark (9.9 cases per 100 000 people) and lowest in Harare, Zimbabwe (0.4 cases per 100 000). The highest rates were mostly in Scandinavia. High rates were recorded among populations in Europe, Oceania, and North America, and low rates in Latin American, Asian, and African populations, including black Americans.
Over the 25 years rates of cancer increased, on average, by around 60%. The largest increases were in Puerto Rico (from 0.5 to 1.6 cases per 100 000, a 220% increase) and the Bas-Rhin region of France (from 3.5 to 7.9 cases per 100 000, or 130%).
Other increases were in Hong Kong (from 1.4 to 1.7 per 100 000, 21%), among white Americans (from 3.8 to 5.6 per 100 000, 47%), and in New Zealand (excluding Maoris) (from 4.5 to 5.6 per 100 000, or 24%).
The incidence in all Scandinavian countries increased by a relatively large amount. The incidence per 100 000 people went up from 5.8 to 9.9 (71% increase) in Denmark, 4.4 to 8.2 (86%) in Norway, 3.0 to 5.0 (67%) in Sweden, and 1.7 to 2.7 (59%) in Finland. In England, the South Thames region saw an increase from 3.4 to 5.4 per 100 000 (59%).
"Testis cancer incidence among the 21 selected populations varied more than 10-fold," wrote the authors. They say that a variety of factors might account for the general increases. Possible reasons range from lifestyle and age of mother at birth to endocrine modulators and low birth weight.
"Given the improvements in the standard of living for many populations over the past century, it is possible that some factor accompanying these changes in lifestyle is responsible for the increase in incidence," they say.
"Increased maternal age and low parity have been suggested to be risk factors for testis cancer in some studies. Reported decreases in age at puberty and early-life infections are also consistent with an increase in testis cancer rates. Lastly, there is speculation that endocrine modulators may increase the risk of testis cancer by interfering with in utero gonadal development. However, there is little epidemiologic evidence supporting this hypothesis."(Abergavenny Roger Dobson)
But the researchers, from the US National Cancer Institute, found big differences, with some rates 10 times higher than others. Why this increase has occurred and what is responsible remain unclear, say the researchers.
Although the incidence of cancer of the testis has risen markedly in many Western populations over the past half century, it has not been clear whether rates in other populations have also increased. In the research, which was published online on 9 February in the International Journal of Cancer (Wiley InterScience, www3.interscience.wiley.com, doi: 10.1002/ijc.20931), the authors examined the incidence of cancer of the testis over the period 1973 to 1997 as reported in 21 registries in countries in America, Asia, Africa, Europe, and Oceania.
The results show that the incidence rose between 1973 and 1997 in most populations, although the increases were highest among populations of European ancestry. The age adjusted incidence for 1993-7was highest in Denmark (9.9 cases per 100 000 people) and lowest in Harare, Zimbabwe (0.4 cases per 100 000). The highest rates were mostly in Scandinavia. High rates were recorded among populations in Europe, Oceania, and North America, and low rates in Latin American, Asian, and African populations, including black Americans.
Over the 25 years rates of cancer increased, on average, by around 60%. The largest increases were in Puerto Rico (from 0.5 to 1.6 cases per 100 000, a 220% increase) and the Bas-Rhin region of France (from 3.5 to 7.9 cases per 100 000, or 130%).
Other increases were in Hong Kong (from 1.4 to 1.7 per 100 000, 21%), among white Americans (from 3.8 to 5.6 per 100 000, 47%), and in New Zealand (excluding Maoris) (from 4.5 to 5.6 per 100 000, or 24%).
The incidence in all Scandinavian countries increased by a relatively large amount. The incidence per 100 000 people went up from 5.8 to 9.9 (71% increase) in Denmark, 4.4 to 8.2 (86%) in Norway, 3.0 to 5.0 (67%) in Sweden, and 1.7 to 2.7 (59%) in Finland. In England, the South Thames region saw an increase from 3.4 to 5.4 per 100 000 (59%).
"Testis cancer incidence among the 21 selected populations varied more than 10-fold," wrote the authors. They say that a variety of factors might account for the general increases. Possible reasons range from lifestyle and age of mother at birth to endocrine modulators and low birth weight.
"Given the improvements in the standard of living for many populations over the past century, it is possible that some factor accompanying these changes in lifestyle is responsible for the increase in incidence," they say.
"Increased maternal age and low parity have been suggested to be risk factors for testis cancer in some studies. Reported decreases in age at puberty and early-life infections are also consistent with an increase in testis cancer rates. Lastly, there is speculation that endocrine modulators may increase the risk of testis cancer by interfering with in utero gonadal development. However, there is little epidemiologic evidence supporting this hypothesis."(Abergavenny Roger Dobson)