After standard neoadjuvant chemotherapy, nearly half of breast cancer patients carrying the BRCA1 gene mutation achieve a complete pathological response (pCR) despite the stage of their disease, according to new research from The University of Texas MD Anderson Cancer Center recently published online in the Journal of Clinical Oncology.
This is the largest study to date showing that the pCR rate is significantly higher in women carrying the BRCA1 mutation (46%) than in BRCA2 carriers (13%) and noncarriers (22%). Researchers did not find a statistical difference in overall survival rates among all the women. Instead, only the BRCA1 carriers who achieved a pCR had improved 5-year, relapse-free survival and overall survival rates.
“While hereditary breast cancers typically carry aggressive tumor features compared to sporadic breast cancers, we found that BRCA1-related tumors were as responsive and sensitive to anthracycline and taxane-based chemotherapy as were sporadic breast cancers,” said Banu Arun, MD, professor in the Department of Breast Medical Oncology at MD Anderson and lead author of the study. “These findings may help physicians determine the best treatment method for this subset of women with unique genetic mutations.” Due to a lack of studies, there is currently no agreement on the most effective chemotherapy regimen for women carrying the BRCA mutation, according to Arun.
Researchers sought to establish whether women with and without the genetic mutations would respond differently to the same treatment. They identified 317 women at varying breast cancer stages who received neoadjuvant chemotherapy and clinical genetic testing for BRCA1 and BRCA2 between 1997 and 2009. Fifty-seven women were BRCA1 carriers, 23 were BRCA2 mutation carriers, and 237 were noncarriers. Following chemotherapy, 61 patients opted for breast-conserving surgery, while 256 women chose mastectomy.
At a median follow-up of 3.2 years, 22% of patients had experienced disease recurrence or death. Neither BRCA status nor type of neoadjuvant chemotherapy received had any significant affect on survival outcomes.
“This new insight tempts us to speculate that the presence of the BRCA1 mutation determines how some women will respond to neoadjuvant chemotherapy. However, we need future prospective studies with larger cohorts and longer-term follow-up to validate these findings and determine optimum treatment,” Arun noted.