Breast Cancer Survivors With BRCA Mutation Have Higher Risk of Second Cancer
People with a BRCA1 or BRCA2 mutation with a history of breast cancer have a higher risk of developing a second primary cancer than people without the mutation, according to a study in The Journal of Clinical Oncology.
Key takeaways
Compared to the average person, breast cancer survivors with a BRCA mutation were much more likely to develop cancer in the opposite breast (called contralateral breast cancer by doctors). They were also more likely to develop ovarian, colorectal, pancreatic, and endometrial cancers.
Compared to female survivors without a BRCA mutation, women with a mutation were more likely to develop cancer in the opposite breast, as well as ovarian, colorectal, and pancreatic cancers.
Compared to male survivors without a BRCA mutation, men with a mutation were more likely to develop cancer in the opposite breast, as well as prostate cancer.
What the results mean for you
If you’ve been diagnosed with breast cancer and know you have a BRCA mutation, the results give you more detailed information about your risk of developing a second cancer. This can help you and your doctor develop a more frequent cancer screening plan that is specially tailored to your situation and preferences. It can also help you make decisions about other steps you might want to take to reduce your risk, including prophylactic mastectomy and prophylactic ovary removal.
Why do the study?
The number of breast cancer survivors in the United States continues to increase, thanks to treatment advances and better screening techniques. Up to 1.5% of these survivors have a BRCA mutation. Researchers wanted to know if people with these mutations might be more likely to develop a new cancer after being treated for breast cancer.
About the study
The study included 25,811 females and 480 males who had been diagnosed with breast cancer between 1995 and 2019. More than 81% of the people were white and more than 67% were first diagnosed with breast cancer when they were younger than 45. All the people in the study had genetic testing.
Overall, 3,671, or about 14%, had a BRCA mutation:
1,840 women had a BRCA1 mutation
7 men had a BRCA1 mutation
1,750 women had a BRCA2 mutation
74 men had a BRCA2 mutation
The people were followed until Dec. 31, 2020.
The researchers compared estimated rates of second primary cancers in people with a history of breast cancer and a BRCA mutation and people in the general population, most of whom haven’t been diagnosed with cancer and don’t have a BRCA mutation.
Detailed results
Compared to people in the general population, people with a BRCA mutation were more likely to develop cancer in the opposite breast, as well as other non-breast cancers.
Women with a BRCA1 mutation were:
15.6 times more likely to develop cancer in the opposite breast
44 times more likely to develop ovarian cancer
4.8 times more likely to develop colorectal cancer
3.03 times more likely to develop pancreatic cancer
2.92 times more likely to develop endometrial cancer
1.98 times more likely to develop lung cancer
Women with a BRCA2 mutation were:
16.8 times more likely to develop ovarian cancer
7.7 times more likely to develop cancer in the opposite breast
5.72 times more likely to develop pancreatic cancer
1.62 times more likely to develop lung cancer
1.4 times more likely to develop colorectal cancer
1.36 times more likely to develop endometrial cancer
Women with a BRCA1 mutation who were first diagnosed with breast cancer at age 45 or younger were 23.5 times more likely to develop cancer in the opposite breast than women who were diagnosed at this age and didn’t have the mutation. Women who were older than 45 when first diagnosed were 9.31 times more likely to develop cancer in the opposite breast. Age at first diagnosis didn’t seem to affect risk in women with a BRCA2 mutation.
Men with a BRCA2 mutation were:
431 times more likely to develop cancer in the opposite breast
20.2 times more likely to develop pancreatic cancer
4.46 times more likely to develop prostate cancer
Compared to survivors without a BRCA mutation, survivors with a BRCA mutation were much more likely to develop a second primary cancer.
Women with a BRCA1 mutation were:
33 times more likely to develop ovarian cancer
3.6 times more likely to develop cancer in the opposite breast
2.93 times more likely to develop colorectal cancer
1.45 times more likely to develop a non-breast or ovarian cancer
Women with a BRCA2 mutation were:
12 times more likely to develop ovarian cancer
3.56 times more likely to develop pancreatic cancer
2.4 times more likely to develop cancer in the opposite breast
Men with a BRCA2 mutation were:
13.1 times more likely to develop cancer in the opposite breast
5.61 times more likely to develop prostate cancer
There was no information on men with a BRCA1 mutation in the paper. This was probably because there were only seven men with this mutation.
Isaac Allen et al., Second Primary Cancer Risks After Breast Cancer in BRCA1 and BRCA2 Pathogenic Variant Carriers. JCO 0, JCO.24.01146.
— Last updated on April 30, 2025 at 7:43 PM