Cancer victims’ relatives ‘more likely to contract disease’

EVEN distant relatives of cancer victims have a higher than average chance of suffering the disease themselves, researchers said yesterday.

A study based in Iceland, where scientists have access to unique family tree data covering the whole population, showed that inheritance played a part in 16 out of 27 cancers. However, even cancers with the strongest family links were not more than twice as likely in first-degree relatives.

The scientists established how often cancers occurred in first to fifth degree relatives of about 32,000 cancer patients over the past 50 years.

A total of 27 cancers were studied, including many of the most common such as lung, breast, prostate, colon and skin.

For 16 cancers, relatives of patients were at a significantly higher risk of developing the disease. In some cases the increased risk extended out to distant third to fifth degree relatives.

Cancers at certain sites of the body also showed a familial association with other cancers. For example, relatives of people with stomach, colon, rectal or womb-lining cancer were more likely to develop any one of these diseases.

Stomach, lung and colon cancers were also seen more frequently in the partners of patients, suggesting the involvement of shared lifestyle and environmental factors.

The seven diseases with the highest increased familial occurrence both in close and distant relatives were breast, prostate, stomach, lung, colon, kidney and bladder cancers.

Study leader Kari Stefansson, chief executive of the drug company deCODE Genetics in Reykjavik, said: “Our findings indicate that genetic factors contribute to the risk of specific cancers, but also that certain types of cancer can be looked upon collectively as broad, complex phenotypes (diseases with distinct characteristics).

DeCODE, which uses genetics to develop new drug treatments, has a genealogy database covering all 288,000 Icelanders currently living and many from past generations.

The researchers compared data from Iceland’s National Cancer Registry with information from the genealogy database.