A new study reveals that cancer in one twin increases the risk for the sibling also developing the disease, Huewire reports.
The study was published Tuesday in JAMA.
Researchers at Harvard University found in the study, conducted with the University of Southern Denmark and University of Helsinki, that twins with any type of cancer developed different types of cancer often, suggesting that there is an overall probability among families for the disease, according to UPI.
"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 Lorelei Mucci, an associate professor of epidemiology at Harvard, in a press release.
For the study, Mucci and her fellow researchers analyzed data from the Nordic Twin Study of Cancer conducted between 1943 and 2010.
A total of 27,156 incident cancers were diagnosed in 23,980 individuals.
The researchers calculated that the risk of cancer in an identical twin whose twin was diagnosed with cancer was 46 percent.
This was the first study to look at twin pairs where both twins had developed cancer.
Previous studies have revealed that cancer risk may be due to a number of environmental factors and lifestyle choices.
"It was surprising that the estimate of heritability of melanoma was the largest of all of the studied cancers", Mucci said.
One of the strongest familial risks was observed for testicular cancer. The types of cancer each developed were not always the same, however.
Also, developing cancer was one of the qualities both identical and fraternal twins share. Cancer was diagnosed in both twins for 3,316 of the pairs, in whom the same cancer was diagnosed among 38% of the identical twins and 26% of the fraternal twins.
Mucci said the findings are relevant to siblings more generally, even though this particular study was based on twins.
