Mutant breast cancer gene puts men at risk

Mutations of a gene implicated in increased risks of breast and ovarian cancers in women are also responsible for raising the threat of several cancers in men, researchers suggested last night. Dutch researchers reinforced suspicions that changes in the BRCA2 gene are linked to higher risks of prostate, pancreatic, bone and throat cancers. Yet the increased risks in the cancers which affected both sexes seemed to be significant only in men, usually under 65. The study by a team at the Leiden University Medical Centre, in the Netherlands, published in the Journal of Medical Genetics, suggests male carriers of the mutated gene were more than twice as likely to have prostate cancer, now the most common cancer in British men. This will fuel the debate of just how screening for the disease should develop. There is already argument over whether men should have surgery or just undergo "watchful waiting" to see how the form of cancer develops.

Despite the fact inherited cancers only account for one in 20 breast cancers - the BRCA2 gene a small proportion of them - some women who know they are at inherited risk of breast cancer already opt for a mastectomy even when they are healthy.
Researchers have previously estimated that women carriers of BRCA2 mutations have a risk of between 26% and 84% of developing breast cancer by the time they are 70, compared with a lifetime one in nine risk of breast cancer in women without the faulty gene.
Just why BRCA2 gene mutations seem important in some cancers and not in others remains a mystery.
The Dutch researchers investigated 139 families with 66 different mutations of the BRAC2 gene, all drawn from a national register of families with breast and ovarian cancers in several family members. Researchers avoided known carriers and studied incidence of cancers in family members with a 50% chance of being a carrier, amounting to 1,811 people.
They then calculated the overall risk of developing these cancers in comparison with the expected rates in the general population. Among 441 people tested for BRAC2, just more than two-thirds carried a mutated gene. In total, there were 158 cases of cancer among the 303 mutation carriers compared with 18 cases among the 138 who did not have a mutated gene.
Carriers of mutated BRAC2 genes were seven times more likely to develop throat cancer and eight times more likely to have pancreatic cancer. Carriers were also 15 times more likely to have bone cancer.
Meanwhile, British scientists at the Breakthrough Breast Cancer centre in London, said last night that they had found a gene, named after Scaramanga, the villainous adversary of James Bond with three nipples. The Scaramanga gene triggers the development of normal breasts but can be a factor in cancer.
About one in 18 people are thought to have an extra nipple. Although this is normal, the charity last night advised such tissue should be checked for abnormalities in the same way as breast tissue.
A protein made by the NRG3 gene has been found in some breast cancers, and the scientists found this signalled embryonic cells to begin forming breast cells.
Professor Alan Ashworth, director of the centre, said: "We already believe that the protein produced by the Scaramanga gene is linked with breast cancer and the next steps are to study this in some detail."

SOURCE: The Guardian