Twins Study Offers Clues to Genetic Risk of Cancer

Source: LiveScience.com, January 2016

A large, new study of identical and fraternal twins in Nordic countries finds that when one twin is diagnosed with any type of cancer, there is a higher than average risk that the other twin will also develop cancer.

This risk of developing cancer was an estimated 14 percent higher in identical twins if one twin had cancer, and 5 percent higher in fraternal twins if one twin had cancer — compared to the average cancer risk of all the people in the study.

The researchers also found that for 20 out of the 23 specific types of cancer studied, if one twin developed one type of cancer, the risk of the second twin also developing that same type of cancer was higher than average. This was true for cancers of the prostate, skin (melanoma), breast, ovary and uterus, according to the study, published today (Jan. 5) in the Journal of the American Medical Association (JAMA).