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Invasive breast cancer outcomes after neoadjuvant chemotherapy similar regardless of locoregional treatment
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SAN ANTONIO — Women with invasive breast cancer who received neoadjuvant chemotherapy experienced comparable DFS, OS and time to progression regardless of their choice of locoregional therapy, according to study results presented at San Antonio Breast Cancer Symposium.
The only exception appeared to be in the subgroup of patients with triple-negative breast cancer. In that subset, patients who underwent lumpectomy experienced longer time to progression than those who underwent mastectomy.
Jennifer De Los Santos
“These findings provide additional evidence that, in women who are appropriate candidates for lumpectomy after neoadjuvant chemotherapy, breast-conserving therapy does not compromise long-term cancer outcomes,” Jennifer De Los Santos, MD, professor at University of Alabama Birmingham School of Medicine, and colleagues wrote.
Neoadjuvant chemotherapy often is used to downstage locally advanced tumors and facilitate breast conservation. Still, the achievement of radiographic complete response or pathologic complete response often does not influence the type of surgery most patients undergo, according to study background.
In a secondary analysis of the TBCRC 017 trial, De Los Santos and colleagues evaluated treatment outcomes of women who received neoadjuvant chemotherapy to determine whether outcomes varied based on type of locoregional treatment.
The analysis included 1,077 women treated at nine NCI-designated cancer centers for stage I to stage III invasive breast cancer from Jan. 1, 2002, through June 16, 2014.
Median age was 50 years (range, 19-87). Slightly less than half (43.9%) had ER-positive and/or PR-positive/HER-2–negative disease, approximately one-third (32.3%) had HER-2–positive disease, and nearly one-quarter (23.8%) had triple-negative disease.
All women underwent neoadjuvant chemotherapy with MRI before and after systemic treatment. Although the type of systemic treatment was not prespecified, receipt of at least 80% of planned cycles was required prior to final MRI.
The majority (62.7%) of study participants underwent mastectomy, whereas 37.3% underwent breast-conserving therapy. Most participants received radiation (breast-conserving therapy group, 84.1%; mastectomy group, 68.3%).
De Los Santos used univariate analysis and multivariable Cox proportional hazard regression to determine covariates associated with OS, DFS and time to recurrence.
Median follow-up was 4.2 years (range, 0.1-13).
During that time, researchers reported 134 recurrences, 168 disease events and 89 deaths.
Among those who achieved pathologic complete response, recurrences occurred in seven of 161 (7.2%) who underwent mastectomy and six of 143 (5.1%) who underwent lumpectomy.
Among those who achieved radiologic complete response — defined as no residual enhancement on post-treatment breast MRI — recurrences occurred in 5% of those who underwent mastectomy and 2.9% of those who underwent lumpectomy.
A multivariable analysis that included all study participants revealed three factors — clinical stage, ER status and achievement of pathologic complete response — independently associated with DFS.
A subset analysis revealed an independent association between lumpectomy and longer time to recurrence among women with triple-negative breast cancer (HR = 0.4; 95% CI, 0.17-0.97). However, this benefit did not translate to longer DFS. – by Mark Leiser
Reference:
De Los Santos J, et al. Abstract S3-06. Presented at: San Antonio Breast Cancer Symposium; Dec. 8-12, 2015; San Antonio.
Disclosure: Please see the abstract for a list of all researchers’ relevant financial disclosures.