BRCA1 and BRCA2 carriers are at high risk of developing a second cancer in their other breast and may opt for a double mastectomy to reduce the risk. However, Dr. Alexandra van den Broek from the Netherlands Cancer Institute in Amsterdam found polygenic risk scores can better determine which of these women will develop a second cancer. Polygenic risk scores were originally developed to try to better predict the risk of developing a first breast cancer. But research suggests it can also help patients who have survived their first breast cancer to better understand their level of risk for a second breast cancer.
The researchers tested this hypothesis in a cohort of about 6,000 breast cancer patients with the BRCA1 mutation and about 4,000 with the BRCA2 mutation. The women hailed from the Netherlands, Spain, the U.K., the U.S., Australia, and Canada.
The polygenic risk scores did indeed predict the risk of a second breast cancer. Also, the difference in the risk of a second breast cancer between different polygenic risk scores can be up to 10% in the 10 years following a first diagnosis, they found.
The researchers will continue to study the significance of low-risk variants and how they interact with other known risk factors, such as age. The findings could be influenced by the fact women with a second breast cancer are more likely to be tested for a BRCA mutation, which may mean they are overrepresented in this study, the researchers noted. They plan to adjust for that in the future.
The results should be validated in an independent cohort, they added.
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