Absolute benefit from adjuvant chemotherapy in triple negative breast cancer (TNBC): A systemic review and meta-analysis.

Abstract

e12501 Background: In general, early stage TNBC has a poor prognosis. Adjuvant chemotherapy is the gold standard therapy and different regimens have shown improved outcome. It is uncertain whether all regimens have similar efficacy and if all patients with TNBC benefit equally from treatment. Methods: We searched PUBMED to identify randomized trials between 2007 and 2017 comparing different adjuvant chemotherapy regimens in breast cancer. Only studies reporting outcomes for patients with TNBC (or hormone receptor negative disease if data on TNBC not reported) were included. The absolute differences between the experimental and the control group for 5-year disease-free survival (DFS) and overall-survival (OS) were extracted. The absolute benefit from treatment was weighted by study sample size and pooled. We then compared differences between various generations of chemotherapy. Meta-regression analysis explored the influence of study-level median follow-up, tumor size, nodal status, median age, menopausal status and generation of chemotherapy on the benefit from adjuvant chemotherapy. Results: Nineteen studies comprising of 22 comparison groups and 11306 patients with TNBC were included in the analysis. Studies comparing chemotherapy regimens of different generations showed the largest difference in 5 year DFS (weighted mean difference 7.4% for 3rd vs. 2nd generation and 5.9% for 2nd vs. 1st generation). Studies comparing chemotherapy regimens from the same generation showed smaller differences in DFS (1.9%, 1.3% and -3.5% for studies comparing 3rd, 2nd and 1st generations, respectively). The weighted differences in 5 year OS were generally lower (0.4% to 5.8%). Meta-regression results are shown in the Table. Conclusions: Later generations of adjuvant chemotherapy result in substantially improved DFS in patients with early stage TNBC with patients with larger tumor size and nodal involvement gaining most benefit irrespective of age and menopausal status. Large differences in 5 year DFS do not translate to similar effects in 5 year OS. Variable DFS β P value Median age -0.144 0.63 Menopausal 0.374 0.21 T2-T4 0.822 0.001 Node positive 0.525 0.04 Follow-up duration -0.024 0.92