medwireNews: Individuals with breast cancer and a BRCA1/2 variant experience comparable survival rates whether they are treated with breast-conserving therapy (BCT) or mastectomy with or without radiotherapy, Chinese researchers suggest.
Yuntao Xie and co-investigators, from Peking University Cancer Hospital and Institute in Beijing, therefore say that “that BCT may be an option for patients who carry a BRCA1/2 variant when the tumor is clinically appropriate for this procedure.”
Their study included 8396 patients with stage I–III primary breast cancer, of whom 187 carried the BRCA1 variant and 304 carried the BRCA2 variant.
Between 2003 and 2015, 37.3% of participants underwent BCT, 18.0% received mastectomy with radiotherapy, and 44.7% received mastectomy alone. The researchers note that neither patients nor physicians were aware of the BRCA1/2 variant status at the time of treatment, meaning that the proportion of patients who underwent each procedure was similar throughout the variant subgroups.
After a median 7.5 years of follow-up, the breast cancer-specific survival (BCSS) rates among BRCA1 carriers were approximately 97% with BCT, 78% with mastectomy plus radiotherapy, and 96% for mastectomy alone.
The corresponding BCSS rates among people with BRCA2 mutations were approximately 97%, 81%, and 97%, with respective rates of 97%, 80%, and 96% among the individuals with neither mutation.
After adjustment for age and year at diagnosis, family history, hormone receptor status, tumor characteristics, and adjuvant therapy, Xie and team found no significant difference in BCSS by surgery type in the people with BRCA1 or BRCA2 variants.
For the individuals with neither variant, BCT was associated with significantly better BCSS than both mastectomy with or without radiotherapy, at hazard ratios of 0.45 and 0.71, respectively.
Similar results were observed for overall survival, and also when the analyses were restricted to individuals with early stage (I or II) breast cancer.
Ipsilateral breast cancer recurrence did not differ significantly by surgery type or mutation status but the rate was nonsignificantly higher among BRCA2 variant carriers who underwent BCT relative to BRCA1 carriers and noncarriers who received the same procedure (7.5 vs 1.4 and 3.9%, respectively).
By contrast, the rate of contralateral breast cancer was significantly higher among BRCA1 and BRCA2 variant carriers than among noncarriers regardless of treatment (13.9%, 13.5%, and 2.5%, respectively).
Writing in JAMA Network Open, Xie and co-authors suggest: “The high risk of contralateral breast cancer may outweigh the benefits associated with BCT for BRCA1/2 variant carriers.”
In an accompanying comment, Marissa Howard-McNatt, from Wake Forest Baptist Health in Winston-Salem, North Carolina, USA says that this conclusion “is at the heart of the conversation with BRCA1/2 variant carriers.”
She adds: “If a patient decides to undergo BCT for their cancer, we would still have to closely screen patients, with mammograms alternating with breast magnetic resonance imaging every 6 months to catch cancer at an early stage, whereas if a patient decides to undergo bilateral mastectomy, this intense screening, which can become emotionally and financially draining for patients, is not needed.”
Howard-McNatt concludes that while the study improves knowledge about treatment regimens for these patients, “surgical choice is a complex decision-making process that the patient and the physician are best to approach in a collaborative way, involving much thought and conversation.”
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JAMA Netw Open 2021; 4: e216259
JAMA Netw Open 2021; 4: e216391