Testicular cancer is the most common form of cancer among men aged 15-40 years old. Although it accounts for only 1% of cancers in Western males, it is unusual in affecting this age range. Incidences of testicular cancer among men of European descent have increased by 3% annually for the past 50 years. The cause of this is not clear. Five-year survival rates have increased from 63% to 90% over the past 30 years, and are now close to 100% when the cancer is diagnosed at an early stage.
The causes of testicular cancer are not clear and nor is the increases in cancer rates. It is known that rates vary with race, with Caucasians up to eight times more likely to develop testicular cancer than Africans or Asians.
The development of testicular cancer is triggered by environmental exposure in the womb. Using mice genetically predisposed to developing testicular cancer, scientists demonstrated that male foetuses exposed to radiation at about 5–6 weeks of pregnancy have an increased risk of developing testicular cancer . This was the first example of induction of testicular cancer by an environmental agent.
Grafting testicular tissue from aborted human foetuses into nude mice has provided a more reliable model for examining the causes of testicular cancer . This was developed in 2010 and has since been used to show that exposure to phthalates, widely-used chemicals previously thought to be linked to testicular cancer, does not affect survival rates or testosterone production .
Professor Richard Sharpe, speaking in 2011, describes the work in his lab on testicular cancer.
It has been difficult to develop animal models because it is rare for animals to develop carcinoma in situ (CIS), which is the precursor to the tumour in humans. However, research has shown that marmosets develop in a similar way to humans, particularly in switching off the OCT4 gene which is linked with CIS development . This could mean that marmosets would be a suitable model for human testicular cancer.
Current treatments include the removal of the affected testicle and chemotherapy using a combination of cisplatin, bleomycin and etoposide. Cisplatin has been used in a wide range of cancers, including ovarian cancer, lymphomas and small cell lung cancer. Cisplatin was originally created by accident while using platinum electrodes in electrolysis. It was the noted that cisplatin prevents cell division in bacteria and later its anti-tumour properties were discovered through experiments on mice.
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