BRCA1 and BRCA2 mutations increase risk of prostate and pancreatic cancer in men, University of Cambridge study finds
Faulty versions of the BRCA1 and BRCA2 genes that are known to increase the risk of breast cancer in men and women, and of ovarian cancer, have now been linked to several other cancers.
BRCA mutations affect about one in 300 to 400 people, but until now studies assessing the cancer risk they pose have been imprecise due to small sample sizes.
Now researchers at the University of Cambridge, funded by Cancer Research UK, have analysed data from almost 3,200 families with one or more members with the BRCA1 mutation and almost 2,200 families with members carrying the BRCA2 mutation.
They found men who carry a BRCA2 mutation have a 27 per cent risk of developing prostate cancer by the time they are 80 years old, which is more than double the rate for non-carriers. BRCA1 mutations were not associated, however, with an increase in prostate cancer risk.
Carrying a defective copy of either BRCA1 or BRCA2 more than doubled an individual’s risk of pancreatic cancer to 2.5-3 per cent by age 80.
There was also an increased risk of stomach cancer, but the number of patients in this dataset was small, due to the rarity of this form of cancer.
Breast cancer risk in men was also significantly increased by mutations in both genes, but the disease is accounting for fewer than one per cent of all male cancer cases in the UK.
A BRCA1 mutation increased a man’s risk of developing breast cancer more than four-fold to 0.4 per cent by age 80, while a BRCA2 mutation raised it 44 times to 3.8 per cent by age 80.
This means an estimated 38 out of 1,000 male carriers of the BRCA2 mutation will develop breast cancer by age 80.
However, the researchers did not find compelling evidence that mutations were linked to increased risk of some other cancers previously thought to be linked to faulty BRCA genes, such as melanoma.
Prof Marc Tischkowitz, from the Department of Medical Genetics at the University of Cambridge, said: “The link between BRCA2 and prostate cancer and pancreatic cancer is now much clearer, thanks to the data we’ve analysed.
“We have also identified a potential link with stomach cancer, but this is based on small numbers and needs further study.”
Cancer Research UK advises that people worried about their risk of cancer should talk to their GP, as doctors can refer patients to a genetics clinic if they think someone has a strong family history and might be at an increased risk.
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