Research shows BRCA-related cancers not a ‘female-only thing’

Although it is widely known that the BRCA1 and BRCA2 gene mutations are linked to breast and ovarian cancer, there has been less certainty about links to other cancers.
 
However, new international research, led by the University of Melbourne and published in the Journal of Clinical Oncology, has shed light on the associated risks and led to calls for broader testing for male carriers.
 
Males who carry a fault in BRCA1 or BRCA2 may be at some increased risk of prostate cancer and male breast cancer, and also could be at greater risk of stomach and pancreatic cancers, the research found.
 
Lead author Dr Shuai Li says the findings highlight the need for male relatives of known BRCA1 and 2 carriers to be informed about their individual cancer risk, in order to benefit from measures for prevention and early detection of cancers.
 
‘They should be … encouraged to be tested, because male and female carriers have the same cancer risks for pancreatic and stomach cancers,’ he said.
 
‘Male carriers can also have increased risk of developing breast cancer. BRCA-related cancers are not a “female-only” thing.’
 
But while the research suggests male carriers are at a heightened risk of some types of cancer, Associate Professor Joel Rhee, Chair of RACGP Specific Interests Cancer and Palliative Care, told newsGP that screening should be carefully considered on a patient-by-patient basis.
 
‘This study suggests that men with these genetic mutations are also at a higher risk from other cancer subtypes, especially stomach and pancreas,’ he said.
 
‘But it’s important that as GPs we don’t jump the gun and rush into organising ad-hoc screening tests of affected patients.
 
‘Screening tests are not risk-free, they can be invasive and/or costly, and they can result in false positive or false negative results.’
 
By using the largest sample size ever in a global cancer study of the same kind, the researchers were able to establish that in addition to female breast and ovarian cancers, BRCA1 and BRCA2 carriers are at risk of male breast, pancreatic and stomach and prostate (BRCA2 carriers only) cancers.
 
However, the gene mutations were not linked to other cancers, such as melanoma, as was previously thought.
 
According to the authors, the study aimed to provide precise, age-specific risk estimates of cancers associated with the BRCA1 and BRCA2 variants, as people who have inherited a pathogenic variant are more likely to develop cancer at younger ages than people who do not have the variant.
 
The researchers examined data of 3184 families carrying the BRCA1 gene and 2157 carrying BRCA2, with at least one family member having a mutation, across 26 studies from 18 countries. The families included 14,979 carriers, 9296 non-carriers and 153,323 untested individuals.
 
Collated data was used to calculate age-specific relative and absolute cancer risks, showing that by age 80 years, the male breast cancer risk for BRCA1 and BRCA2 carriers was down to 0.4%.
 
The estimated age-specific relative and absolute risks suggest that, in addition to breast and ovarian cancers, the clinical management of carriers should focus on strong associations with prostate (BRCA2 carriers only), pancreatic and stomach cancers.
 
In Australia, cancer screening is directly linked with higher survival rates, and GPs are instrumental in encouraging screening participation.
 
Associate Professor Rhee says the ‘take-home message for GPs’ is that they need to be mindful that BRCA1 and BRCA2 may increase the risk of stomach and pancreatic cancer as well as other cancer sub-types.
 
‘Secondly, GPs should continue taking a good, comprehensive family history, ensure they are kept up to date, and keep an eye out for possible familial cancer syndromes or mutations,’ he said.
 
‘If concerned, then the patient should be referred for genetic counselling and consideration of genetic testing.
 
‘And finally, GPs should be guided by advice from familial cancer services/sub-specialists to implement a personalised screening and early detecting program for patients who might carry one of these genetic mutations.’
 
The authors believe the findings will change guidelines on clinical management of mutation carriers, as the study provides the most up-to-date evidence of accurate cancer risks for BRCA1 or BRCA2 mutation carriers.
 
‘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,’ author Professor Antonis Antoniou said.
 
‘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.’
 
There are now plans to use collected data to also investigate cancer risks among carriers of other genes, such as ATM, CHEK2 and TP53.
 
The RACGP’s Genomics in general practice guidelines provide GPs with evidence-based recommendations for identifying patients at risk of disease and targeting treatment, including genetic carriers of all types of cancer.
 
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