According to the results of a small study, approximately 20% of women with triple-negative breast cancer are carriers of a BRCA1 or BRCA2 gene mutation. Triple-negative breast cancer patients with these mutations appear to have better survival than patients without these mutations. These results were recently presented at the 2010 Breast Cancer Symposium.[i]
Some breast cancers display different characteristics that require different types of treatment. The majority of breast cancers are hormone receptor-positive, meaning that the cancer cells are stimulated to grow by exposure to the female hormones estrogen and/or progesterone. These cancers are typically treated with hormonal therapy that reduces the production of these hormones or blocks their effects. Other cancers are referred to as HER2-positive, which means that they overexpress the human epidermal growth factor receptor 2, part of a biologic pathway that is involved in replication and growth of a cell. HER2-positive breast cancers account for approximately 20-25% of breast cancers and are treated with agents that target the receptor to slow growth and replication.
Triple-negative breast cancer refers to cancers that are estrogen receptor-negative, progesterone receptor-negative, and HER2-negative. Triple-negative breast cancers tend to be more aggressive than other breast cancers and have fewer treatment options. Research is ongoing to determine prognostic factors such as gene mutations that may impact prognosis and help to individualize care.
In the current study, researchers from the M. D. Anderson Cancer Center evaluated the frequency and effects of BRCA1 and BRCA2 gene mutations among 77 women with triple-negative breast cancer. Inherited mutations in these genes can be passed down through either the mother’s or the father’s side of the family and greatly increase the risk of breast and ovarian cancer.
- 15 of the 77 patients (20%) had a BRCA1 or BRCA2 mutation.
- Five-year relapse-free survival was 86% for patients with a BRCA mutation compared with 52% for patients without a BRCA mutation.
The researchers concluded that triple-negative breast cancer patients with BRCA mutations experienced a significantly lower recurrence rate. These findings were unexpected because previous studies had not shown a difference in recurrence rates.
Patients with triple-negative breast cancer may wish to speak with their healthcare team regarding the risks and benefits of genetic testing.
It should be noted that other studies have not found as high a rate of BRCA mutations in women with triple negative breast, so it is possible that the results of this study represent an overestimate.
[i] Gonzalez-Angulo M, Chen H, Timms K, et al. Incidence and outcome of BRCA mutation carriers with triple receptor-negative breast cancer (TNBC). Presented at the 2010 Breast Cancer Symposium, Washington, DC, October 1-3, 2010. Abstract 160.