First Gene For Testicular Cancer Discovered
A consortium of international scientists said (2/1/00) they have located the first gene for susceptibility to testicular cancer. British researchers who led the study said the gene dubbed TGCT1 on chromosome X is inherited from the mother and can increase a man's risk of testicular cancer by up to 50 times. The finding brings scientists a step closer to finding the gene, which could lead to earlier detection, treatment and cure of the most common cancer among young men. "What we have achieved is the localization of the first testicular cancer susceptibility gene. What we need to do now is actually isolate the gene itself," Professor Mike Stratton, of the Institute of Cancer Research in the UK, told a press conference in London. The gene is one of about 300 on the long arm of chromosome X. Stratton and his colleagues hope to work out which one is TGCT1 within the next 2 to 5 years.
"This work will be facilitated enormously by the newly emerging genome sequence, the first draft of which we expect to see late this year," Stratton added, referring to the Human Genome Project, which will map all of the genes in the human body. Testicular cancer affects about one in 500 men and is most common among men aged 25 to 29. The disease has increased steadily since the 1930s. Cases in Denmark, which along with Switzerland and Norway have the highest rates in the world, have trebled. Familial testicular cancer accounts for an estimated 20% of cases, so scientists know that other genes are also involved. Doctors also suspect that environmental factors and exposure to higher levels of the female hormone estrogen in the womb are contributing factors to the increase in the disease. The scientists working for the International Testicular Cancer Linkage Consortium located the TGCT1 gene by studying 134 families worldwide with two or more cases of the disease. It is found in a third of families with a history of the disorder. The finding, which is the culmination of 10 years of research, is published in the journal Nature Genetics. In addition to improving detection and treatment of testicular cancer, which has a 90% to 95% cure rate if found early, Stratton said the discovery has wider implications for other cancers with higher death rates.
"Testicular cancer is unusual because of its high cure rate. By finding out more about the molecular biology of the underlying causes and its pathogenesis we hope to be able to work out why it is so curable," he said. "The implications of that may be that we can see why other cancers, which are not so curable, are different." Risk factors for testicular cancer include a family history of the disease and malformed or undescended testicles. There is also a higher incidence among first-born sons and non-identical twins.
SOURCE: Reuters Health, Feb. 4, 2000.
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