The study, conducted by deCODE Genetics in Iceland, examined the rates at which cancer occurred among all first to fifth-degree relatives of 32,000 patients who had cancer diagnosed between 1955 and 2002.

A first-degree relative is a parent or child or sibling who shares 50 per cent of an individual's DNA. Fifth-degree relatives, such as great-great-great grandparents, share 3.125 per cent of DNA with the patient.

Details of the study were published today in the open-access journal Public Library of Science Medicine.

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

For 16 of these, relatives of patients were at a significantly higher risk of developing the disease.

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.

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

The study sheds light on the way in which different cancers follow patterns of inheritance, and could help doctors to develop strategies for detecting, treating and preventing diverse forms of the disease.

"The next step is to isolate the key genes contributing to the common forms of the disease and to use this to develop better medicine," said Kari Stefansson, chief executive of deCODE genetics.

"At the same time it is crucial to emphasise that lifestyle and environmental factors play a very significant role in the development of cancer."