Issue link: http://viewer.e-digitaledition.com/i/661333
Researchers Probe Genetic Underpinnings of Testicular Cancer BY THOMAS CROCKER TESTICUL AR CANCER IS far less com- mon in the United States tha n other ma lig na ncies. The A merica n Ca ncer Society estimated approximately 8,400 new cases would be diagnosed in 2015, compa red w it h a bout 1 33 ,0 0 0 new cases of colon a nd recta l ca ncer com- bined a nd nea rly 221,000 new cases of prostate ca ncer. In terms of heritabil- ity, however, testicular cancer eclipses more preva lent forms of ca ncer. Scientists a lready knew the herita- bilit y of testicula r ca ncer was higher tha n that of other t y pes of ca ncer, but the new resea rch adds precision to the understa nding of t he ex tent of t hat g reater risk. "Sca ndinavia n studies have previ- ously documented the sibling relative risk for testicular cancer as being very high, in the region of tenfold for broth- ers of ca ses a nd four- to si x fold for fathers and sons of cases," says Clare Turnbull, MD, PhD, Senior Researcher at the Institute of Ca ncer Resea rch, L ondon , a nd Cl i n ica l L ea d for t he Genomics England 100,000 Genomes Project. " This was recog nized to be substantially higher than the familial relative risk for many common cancer types, such as breast cancer and colorec- tal cancer, where the risk to a sibling of a case is only twofold elevated above the population risk." Scientists a re g radua lly uncover- ing the genetic va ria nts a ssociated w it h r i sk for t es t icu la r ca ncer. I n 2013, researchers from the Perelman School of Medicine at the University of Pennsylvania announced the discovery of four new variants. The number of known testicular cancer-linked genetic variants currently stands at 25, accord- ing to Dr. Turnbull. "Our g roup identif ied t he major- it y of t he se, a nd a l l of t hem were identif ied through experiments a nd collaborations in which we've partici- pated," Dr. Turnbull says. "[For a recent study,] we wanted to collaborate with the Swedish Population Registry [a data- base of 15.7 million people] data group to review the heritability of testicular germ cell tumor using a much larger data set than had previously been used, and then complement this population- based analysis ... by looking at our large Half-heritable: HEREDIT Y CONFERS NE ARLY HALF OF A MAN'S RISK FOR TESTICUL AR CANCER, ACCORDING TO A RECENT STUDY BY AN INTERNATIONAL TE AM OF SCIENTISTS. 1 8