Eccles, MD, University of Southampton and University Hospital Southampton NHS Foundation Trust, United Kingdom, and colleagues looked at survival following treatment for the initial breast cancer diagnosed only.
Mutations in these genes stop DNA repairing itself and increase the risk of cancer developing.
The researchers say that in the future this information could help women and their doctors make informed choices about treatment.
The PARP inhibitor is now available to patients with deleterious or suspected germline BRCA-mutated (bBRCAm), human epidermal growth factor receptor 2 (HER2)-negative metastatic breast cancer (MBC) who have been previously treated with chemotherapy in the neoadjuvant, adjuvant or metastatic setting. BRCA mutations were identified in 136 (24%) of patients with triple-negative breast cancer, and 123 of these women (90%) had a BRCA1 mutation.
"This class of drugs has been used to treat advanced, BRCA-mutated ovarian cancer and has now shown efficacy in treating certain types of BRCA-mutated breast cancer", Richard Pazdur, M.D., director of the FDA's Oncology Center of Excellence, said in a statement. The National Cancer Institute at the National Institutes of Health estimates approximately 252,710 women will be diagnosed with breast cancer this year, and 40,610 will die of the disease.
About a third of those included in the study with the BRCA mutation had a double mastectomy to remove both breasts after being diagnosed with cancer. The Prospective Outcomes in Sporadic vs Hereditary breast cancer (POSH) study recruited 2,733 young women with breast cancer between 2000 and 2008.
But the researchers said surgery may still be beneficial for these patients to reduce their risk of a new cancer developing in the longer term. Half had breast-conserving surgery, and half had a mastectomy.
She said she was now keen to understand how women fared more than 10 years after their diagnosis.
"Decisions about timing of additional surgery aimed at reducing future second primary-cancer risks should take into account patient prognosis associated with the first malignancy and patient preferences", the authors write.
Eccles and her colleagues noted that the findings might not apply to older breast cancer patients with a BRCA mutation. While only about five percent of breast cancers are diagnosed in women younger than 40, a high proportion of deaths fall in this age category.
In an editorial accompanying the study, Peter Fasching, MD, of the Friedrich Alexander University Erlangen-Nuremberg in Germany, observed that while 338 patients in the POSH cohort had a BRCA1 or BRCA2 mutation, only 54% of the mutation carriers - 182 women - had been identified through routine healthcare.
The faulty genes are also linked to an increased risk of ovarian and prostate cancers, as well as breast cancer.