Having cancer in the family can increase the chances of developing another form of the disease besides the one affecting your relative, a study has found.
Scientists looked at cases involving 23,000 people with cancers in 13 areas of the body.
For every cancer site, there was an increased risk of the same disease occurring in first-degree relatives such as sons and daughters, or siblings.
But there was also evidence that a family history of one kind of cancer could significantly raise the risk of others.
People with a first-degree relative with cancer of the larynx had triple the normal risk of developing oral and pharyngeal cancer.
Those closely related to someone with oral and pharyngeal cancer had a four-fold increased risk of oesopheagal cancer while breast cancer doubled the risk of ovarian cancer for female family members.
Men had a 3.4-fold increased risk of prostate cancer if a first-degree relative had bladder cancer.
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The research, published in the journal Annals of Oncology, also supported some associations that were already known.
These included the 1.5-times greater risk of women developing breast cancer if they have a family history of bowel cancer.
The international team of researchers looked at cancers affecting the mouth and pharynx, nasopharynx, oesophagus, stomach, bowel, liver, pancreas, larynx, breast, womb, ovaries, prostate and kidneys.
Study leader Dr Eva Negri, head of the Laboratory of Epidemiologic Methods at the Mario Negri Institute for Pharmacological Research in Milan, Italy, said: "Besides confirming and quantifying the well-known excess risks of people developing the same cancer as their first-degree relative, we have identified increased risks for developing a number of different cancers.
"We have also found that if a patient was diagnosed with certain cancers when they were younger than 60, the risks of a discordant cancer developing in family members were greater."
In some cases, the links between different cancers may be due to shared environmental factors, such as family smoking and drinking habits, said Dr Negri.
But there was also evidence of genetic factors affecting multiple cancer sites.
"These findings may help researchers and clinicians to focus on the identification of additional genetic causes of selected cancers and on optimising screening and diagnosis, particularly in people with a family history of cancer at a young age," Dr Negri added.
Eluned Hughes, from the charity Breakthrough Breast Cancer, said: "This study confirms what we already know about the associations between family history and breast cancer risk.
"Some breast cancers do run in the family, however it's vital that women remember most cases are not hereditary.
"There is no single cause of breast cancer - it results from a combination of our genes, environment and lifestyle factors. In order to fully understand the causes of breast cancer, we need to study more women over a longer period of time."