By following sets of Nordic twins for some 32 years, an international team of researchers found the risk of developing some cancers — particularly prostate, melanoma, breast, ovarian, and uterine cancers — is influenced by genetics.
The team followed 80,309 monozygotic and 123,382 same-sex dizygotic twins from Denmark, Finland, Norway, and Sweden for a median 32 years, as it reports this week in the Journal of the American Medical Association. In that time, 27,156 incident cancers were diagnosed in 23,980 individuals.
"Earlier studies were not critically large enough to be able to provide any information about heritability for [some] cancers," Lorelei Mucci, the study's lead author and associate professor of epidemiology at the Harvard TH Chan School of Public Health, tells Stat News. "Our ability to provide information about the relative contribution of genetic factors for these more rare cancers is really important."
Mucci and her colleagues report that twins whose co-twin was diagnosed with cancer had a higher risk of developing cancer themselves, and that risk was higher for monozygotic than for dizygotic twins.
Overall, they estimate cancer heritability to be 33 percent, with some types of cancer exhibiting higher or lower heritability. Melanoma, for instance, showed 58 percent heritability, while ovarian cancer has 39 percent heritability and breast cancer 31 percent.