TESTUCULAR CANCER-4 RISKS

Scientists have identified four new genetic variants associated with an increased risk of testicular cancer, the most commonly diagnosed type in young men. Scientists from the Perelman School of Medicine at the University of Pennsylvania looked at the genomes of more than 13,000 men. The discovery of these genetic variations - chromosomal "typos," so to speak - could ultimately help researchers better understand which men are at high risk and allow for early detection or prevention of the disease. "As we continue to cast a wider net, we identify additional genetic risk factors, which point to new mechanisms for disease," said Katherine L Nathanson, associate professor in the division of Translational Medicine and Human Genetics within the department of Medicine. "Certain chromosomal regions, what we call loci, are tied into testicular cancer susceptibility, and represent a promising path to stratifying patients into risk groups - for a disease we know is highly heritable," Nathanson said. Tapping into three genome-wide association studies (GWAS), the researchers analysed 931 affected individuals and 1,975 controls and confirmed the results in an additional 3,211 men with cancer and 7,591 controls. The meta-analysis revealed that testicular germ cell tumour (TGCT) risk was significantly associated with markers at four loci - 4q22, 7q22, 16q22.3, and 17q22, none of which have been identified in other cancers. Additionally, these loci pose a higher risk than the vast majority of other loci identified for some common cancers, such as breast and prostate. Testicular cancer is relatively rare; however, incidence rates have doubled in the past 40 years. It is also highly heritable. If a man has a father or son with testicular cancer, he has a four-to six-fold higher risk of developing it compared to a man with no family history. That increases to an eight-to 10-fold higher risk if the man has a brother with testicular cancer. "This analysis is the first to bring several groups of data together to identify loci associated with disease and represent the power of combining multiple GWAS to better identify genetic risk factors that failed to reach genome-wide significance in single studies," said Nathanson. The study was published in journal Nature Genetics.