A study on twins in the Nordic area conducted by researchers at Harvard University, in collaboration with the University of Helsinki and University of Denmark, found that when one twin is diagnosed with cancer, the other sibling is highly at risk of developing any type of cancer as well, reported United Press International on Tuesday.
The study not only shows the likelihood of cancer in twins, but its overall extensiveness in families as well.
"Prior studies had provided familial risk and heritability estimates for the common cancers -- breast, prostate, and colon -- but, for rarer cancers, the studies were too small, or the follow-up time too short, to be able to pinpoint either heritability or family risk," said associate professor of epidemiology at Harvard Lorelei Mucci.
The study, which was published on the Journal of the American Medical Association, examined the health records of 80,309 monozygotic (identical) and 123,383 dizygotic (fraternal) twins from health registries of Finland, Denmark, Sweden and Norway.
The researchers found that 23 percent of the subjects were diagnosed with cancers, where 38 percent of identical twins and 26 percent of fraternal twins suffer from the same cancer type.
Medical News Today noted on Wednesday that those fraternal twins where one is diagnosed with cancer, the risk of the other sibling being diagnosed with the disease was 37 percent, while identical twins had 46 percent chance.
The study also found that the overall heritability of cancer among twins was approximately 33 percent.
Notable heritability was found in certain cancer types, with 27 percent for uterine cancer, 31 percent for breast cancer, 38 percent for kidney cancer, 39 percent for ovarian cancer, 43 percent for non-melanoma skin cancer, 57 percent for prostate cancer and 58 percent for skin melanoma.
As fraternal twins are genetically the same with siblings who are not twins, cancer risk among fraternal twins may be a good identifying factor for the risk of the disease for the entire family where one sibling is diagnosed with cancer.
"Findings from this prospective study may be helpful in patient education and cancer risk counseling," said the study's co-author Jaakko Kaprio from the University of Helsinki.
