Among women with the BRCA1 and/or BRCA2 mutations, the age of diagnosis of breast cancer is strongly associated with their risk of developing a second breast cancer in their contralateral (opposite) breast. These results were recently published as a rapid communication in the Journal of Clinical Oncology.
Individuals who have certain mutations referred to as the breast cancer gene 1 (BRCA1) and/or the breast cancer gene 2 (BRCA2) are at an increased risk of developing breast cancer within their lifetime. Often, patients with a strong family history of breast cancer are tested for these genetic mutations.
If an individual tests positive for either, or both of the BRCA1/2 mutations, they can decide upon the way in which they would like to prevent the disease from developing and/or undergo frequent screening. Strategies range from more radical measures such as a prophylactic bilateral mastectomy (removal of both breasts prior to a diagnosis of cancer) to less aggressive measures such as screening at frequent intervals so the cancer can be diagnosed and treated in its earliest stages.
Researchers recently conducted a study to help determine if the age of diagnosis of breast cancer among BRCA1 and/or BRCA2 mutation carriers was associated with a risk of developing breast cancer in the opposite breast of these patients within their lifetime.
The study included 6,294 patients who had been diagnosed with breast cancer under the age of 50 years. The patients were tested for the most prevalent BRCA1/2 mutations, and were followed for 12.5 years. Of these patients, 578 developed contralateral breast cancer.
- The risk for developing contralateral breast cancer was 2-3 times higher among patients with BRCA1/2 mutations, compared to those without the mutations.
- Ten years following the initial breast cancer diagnosis, the cumulate risks for developing contralateral breast cancer were 21.1% for those with the BRCA1 mutation, 10.8% for those with the BRCA2 mutation, and 5.1% for those without a mutation.
- Age of the first breast cancer was a significant predictor of the risk of a second contralateral breast cancer. However, this association only existed for those with BRCA1/2 mutations.
- Specifically, patients diagnosed with their first breast cancer before the age of 41 years had an approximately 24% increased risk of developing contralateral breast cancer 10 years following the initial diagnosis (25.5% for BRCA1 mutations and 17.2% for BRCA2 mutations).
- Patients diagnosed with their initial breast cancer between the ages of 41 and 49 years had a 12.6% risk of developing a contralateral breast cancer 10 years following their initial diagnosis (15.6% for BRCA1 mutations, and 7.2% for BRCA2 mutations).
The researchers concluded that “Age at first breast cancer is a strong risk factor for cumulative [contralateral breast cancer] risk in BRCA1/2 mutation carriers. Considering the available evidence, age-specific risk estimates should be included in counseling.”
Patients with a strong family history of breast cancer should speak with their physician to determine if they might benefit from genetic testing. Among individuals with BRCA1 and/or BRCA2 mutations who have been diagnosed with breast cancer, discussions with healthcare providers should include the age of initial diagnosis to create a plan for optimal screening or prevention measures for a contralateral breast cancer.
Reference: van den Broek A, van’t Veer, L, Hooning M, et al. Impact of age at primary breast cancer on contralateral breast cancer risk in BRCA1/2 mutation carriers. Journal of Clinical Oncology. 2016; 23(5): 409-418. Available at: http://jco.ascopubs.org/content/34/5/409.abstract. Accessed February 18, 2016.