By Peter Russell
WebMD Health News
Reviewed by Arefa Cassoobhoy, MD, MPH
Sept. 9, 2015 -- Almost 50% of the risk of getting testicular cancer comes from the DNA passed down from our parents, according to a new study.
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Typically, genetics accounts for just 20% of the calculation doctors make to gauge someone's odds of getting other types of cancer, say scientists at The Institute of Cancer Research (ICR) and colleagues in Europe and the U.S.
The researchers used two different methods to analyze the risk of testicular germ-cell tumors -- the most common type of testicular cancer.
One approach explored the history of the disease in families across 15.7 million people. This Swedish database included 9,324 cases of testicular cancer.
They then looked in detail at the genetic code of almost 6,000 U.K. men from two previous studies, 986 of whom had been diagnosed with the disease.
The combined analysis revealed that 49% of all the possible things contributing to testicular cancer risk are inherited.
It found that the inherited risk comes from a large number of minor mutations in DNA code, rather than one faulty gene with a big effect. But the scientists say only 9.1% of the gene mutations that can cause testicular cancer have been discovered so far.
"Around half of a man's risk of developing testicular cancer comes from the genes he inherits from his parents -- with environmental and behavioral factors contributing to the other half," says Dr. Clare Turnbull, senior researcher in genetics and epidemiology at the ICR, in a statement. "Our findings have important implications in that they show that if we can discover these genetic causes, screening of men with a family history of testicular cancer could help to diagnose those at greatest risk, and help them to manage that risk."
But, Turnbull says, "our study also shows that much work remains to be done. There are a lot of genetic factors that cause testicular cancer which we are yet to find."
The research, published in the journal Scientific Reports, was funded by the Movember Foundation, The Institute of Cancer Research, and Cancer Research UK.
"This is a significant development in the fight for a world where no man dies of testicular cancer," says Sam Gledhill, the Movember Foundation's global manager for testicular cancer programs, in a statement. "Dr. Turnbull and her team at the ICR have generated important evidence to demonstrate that genetic factors might in the future help identify men and boys who have a higher risk of developing testicular cancer.
"These discoveries help to unlock the mysteries of this relatively poorly understood cancer and may ultimately identify potential treatment targets to fight this disease."
SOURCES: The Institute of Cancer Research. Turnbull, C. Scientific Reports, 2015.
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