BRCA1/2 Mutations Linked with Better Outcome in Triple-negative Breast Cancer

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.

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BRCA1-2 Mutations Increase Risk of Cancer in Opposite Breast

Among women with breast cancer, those with a BRCA1 or BRCA2 gene mutation are much more likely than other women to develop a second breast cancer in the opposite breast. These results were published in the Journal of Clinical Oncology.

Some women who have been diagnosed with breast cancer will eventually develop a second breast cancer in the opposite breast. This is referred to as a contralateral breast cancer. The risk of a second breast cancer among women who have already had breast cancer is higher than the risk of a first breast cancer among women in the general population.

A factor that may influence the risk of contralateral breast cancer is the presence of BRCA1 or BRCA2 gene mutations. Inherited mutations in these genes—which can be passed down through either the mother’s or the father’s side of the family—have been found to greatly increase the lifetime risk of developing breast and ovarian cancer.

To evaluate the relationship between BRCA1 or BRCA2 mutations and risk of a subsequent contralateral breast cancer, researchers conducted a study among more than 2,000 breast cancer patients, some of whom had been diagnosed with a contralateral breast cancer and some of whom had not. Women were only included in the contralateral breast cancer group if their contralateral cancer was diagnosed at least one year after their initial cancer. All of the women had been diagnosed with their first breast cancer before the age of 55.

All of the study participants were tested for BRCA1 and BRCA2 mutations.

Compared with women without a BRCA1 or BRCA2 mutation, risk of a subsequent contralateral breast cancer was 4.5 times higher among women with a BRCA1 mutation and 3.4 times higher among women with a BRCA2 mutation.

Among women with a BRCA1 mutation, a younger age at the time of initial breast cancer diagnosis increased the likelihood of a subsequent contralateral breast cancer.

Information about risk of a subsequent contralateral breast cancer may help guide breast cancer management among women with BRCA1 or BRCA2 mutations.

Reference: Malone KE, Begg CB, Haile RW et al. Population-based study of the risk of second primary contralateral breast cancer associated with carrying a mutation in BRCA1 or BRCA2. Journal of Clinical Oncology. [early online publication]. April 5, 2010.

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