By Ian Lewis
Having a family history of one form of cancer can significantly increase people's risk of developing another, according to a new study.
The study by an international team of researchers - published in the Annals of Oncology journal - looked at 23,000 people with cancers in 13 areas of the body including the stomach, mouth, liver, pancreas, larynx, breast, womb, ovaries, kidneys and prostate.
It found that men were 3.4 times likelier to develop prostate cancer if a close relative such as a parent or sibling had bladder cancer.
And those who had a 'first-degree relative' with cancer of the larynx had three times the normal risk of developing oral and pharyngeal cancer, the researchers found.
Having breast cancer doubled the risk of ovarian cancer for women's close female relatives while the chances of developing oesophageal cancer increased four-fold for people closely related to someone with oral and pharyngeal cancer.
Meanwhile, some hereditary associations that were already known were supported by the study's findings. They included women being 1.5 times likelier to develop breast cancer if there was a family history of bowel cancer.
Dr Eva Negri, of the Mario Negri Institute for Pharmacological Research in Milan, Italy, led the study.
She said as well as confirming the increased risk that people had of developing the same form of cancer as a close relative, the study had identified the increased risks for developing a number of different cancers.
Dr Negri added: "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."
She said although the links could, in some cases, be due to shared environmental factors such as smoking and drinking habits, there was also evidence genetic factors played a part.
"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," she added.
Eluned Hughes, of the Breakthrough Breast Cancer charity, 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."