Researchers from the US National Cancer Institute in 2005 have reported a 60% increase in testicular cancer over the past 25 years. Statistics were collated across 21 populations covering five continents. Most populations showed the highest increase between 1973-1997 but researchers are uncertain why this should be the case and why there should be an increase in testicular cancer rates at all.
Highest rates of testicular cancer are in Denmark, with 9.9 cases per 100,000 men; this contrasts starkly with Zimbabwe (0.4. cases per 100,000). Overall, the highest incidence of testicular cancers occur in Europe, Oceania, and North America and low rates in Latin American, Asian, and African populations, including black Americans.
Researchers have speculated that changes in lifestyle may account for some increase in testicular cancer. Other studies suggest relationships between early-life infections and testicular cancer. Article Source: US National Cancer Institute
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