People who carry the BRCA1 or BRCA2 gene mutation have an increased risk of pancreatic, stomach and prostate cancers, as well as the previously well-known risk of breast and ovarian cancers – but not for melanoma, according to new University of Melbourne led research calling for increased testing in male carriers to detect the cancers early.
The study used the largest sample size ever in a cancer study of the same kind worldwide, critiquing 22 cancers to establish that in addition to female breast and ovarian cancers, BRCA1/2 carriers are at risk for male breast, pancreatic, stomach and prostate (BRCA2 carriers only) cancers, but not other cancers as previously thought. Significantly, the study team found that BRCA1/2 carriers did not have higher risk of melanoma.
Lead author and Victorian Cancer Agency Early Career Research Fellow Dr Shuai Li said the research suggested male relatives of known BRCA1/2 carriers should be informed about their individual cancer risk.
“They should be informed about cancer risk and encouraged to be tested, because male and female carriers have the same cancer risks for pancreatic and stomach cancers, and male BRCA2 carriers also have increased risk of prostate cancers. Male carriers can also have increased risk of developing breast cancer. BRCA-related cancers are not a ‘female only’ thing,” Dr Shuai Li said.
Published today in the Journal of Clinical Oncology, the research by Dr Li and research partners at University of Cambridge and Sapienza University in Rome has provided the most up-to-date evidence and most precise cancer risks for BRCA1 or BRCA2 mutation carriers. The findings are expected to change guidelines on clinical management of BRCA1/2 mutation carriers.
Dr Li said while rare, incidences of pancreatic and stomach cancers are rising, and because they are difficult to detect and have low survival rates, the study showed how important it is to screen for upper gastrointestinal tract malignancies in carriers, particularly for those under 65 years of age.
Researchers used the data of 3,184 BRCA1 families and 2,157 BRCA2 families (with a least one family member having a mutation) of 26 studies from 18 countries. The families included 14,979 carriers, 9,296 non-carriers and 153,323 untested individuals.
Senior author Professor Antonis Antoniou from University of Cambridge said it had been known for some time that the gene mutations were linked to breast and ovarian cancer, but there had been uncertainty about other cancers.
“These large datasets of patients have allowed us to estimate with much greater accuracy the extent to which faulty BRCA1 and BRCA2 genes increase the risk of several cancers. At the same time, the findings will be reassuring because they show that many other cancers are not linked to the BRCA1 and BRCA2 genes,” Professor Antoniou said.
The research team now plan to use prospectively collected data of BRCA1/2 carriers to further refine the findings, using the same method to investigate the cancer risks of carriers of other genes, such as ATM, CHEK2 and TP53.