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Purpose: Residual cancer burden (RCB) index after neoadjuvant chemotherapy (NAC) is highly prognostic in patients with breast cancer (BC) but does not account for subtype or the precise impact of residual nodal burden (RNB). We aimed to precisely de ne the effect of RNB on survival by subtypes. Methods: Adult women with non-metastatic BC diagnosed from 2006-2021 in the National Cancer Database (NCDB) who received NAC followed by surgery within 8 months were included. RNB was also evaluated as a predictor of mortality with multivariable logistic regression. Kaplan-Meier analyses were performed to compare overall survival. Results: 51,917 patients were included. After adjustment, ypN stage was the strongest predictor of mortality, with an odds ratio (OR) of 2.24 (95% CI 2.08-2.41) for ypN1 vs ypN0 and increased with increasing nodal burden - ypN2 vs ypN0 OR 5.03, 95% CI 4.60-5.51 and ypN3 vs ypN0 OR 8.85, 95% CI 7.88-9.93. Stratification of survival curves with higher RNB is most pronounced for triple-negative breast cancer (TNBC) with an absolute difference of 64% in 5-year overall survival between ypN0 and ypN3 patients, and lowest for the ER+/HER2- subtype with a 25% absolute difference in 5-year OS between ypN0 and ypN3 patients. On interaction analysis, ypN status was a stronger predictor of mortality for the TNBC subtype compared to other subtypes. Conclusion: RNB has a significantly different impact on survival by BC subtypes. Future study of optimal therapeutic strategies for patients with residual nodal disease after NAC should account for subtype specific differences in prognosis.
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PURPOSE: Residual cancer burden (RCB) index after neoadjuvant chemotherapy (NAC) is highly prognostic in patients with breast cancer (BC) but does not account for subtype or the precise impact of residual nodal burden (RNB). We aimed to precisely define the effect of RNB on survival by subtypes. METHODS: Adult women with non-metastatic BC diagnosed from 2006 to 2021 in the National Cancer Database (NCDB) who received NAC followed by surgery within 8 months were included. RNB was also evaluated as a predictor of mortality with multivariable logistic regression. Kaplan-Meier analyses were performed to compare overall survival. RESULTS: 51,917 patients were included. After adjustment, ypN stage was the strongest predictor of mortality, with an odds ratio (OR) of 2.24 (95% CI 2.08-2.41) for ypN1 vs ypN0 and increased with increasing nodal burden-ypN2 vs ypN0 OR 5.03, 95% CI 4.60-5.51 and ypN3 vs ypN0 OR 8.85, 95% CI 7.88-9.93. Stratification of survival curves with higher RNB is most pronounced for triple-negative breast cancer (TNBC) with an absolute difference of 64% in 5-year overall survival between ypN0 and ypN3 patients, and lowest for the ER+/HER2- subtype with a 25% absolute difference in 5-year OS between ypN0 and ypN3 patients. On interaction analysis, ypN status was a stronger predictor of mortality for the TNBC subtype compared to other subtypes. CONCLUSION: RNB has a significantly different impact on survival by BC subtypes. Future study of optimal therapeutic strategies for patients with residual nodal disease after NAC should account for subtype-specific differences in prognosis.
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INTRODUCTION: Axillary response to neoadjuvant endocrine therapy (NET) for the treatment of hormone receptor-positive breast cancer (HR+ BC) is not well-described. This study was designed to characterize nodal response after NET. METHODS: Patients receiving NET followed by curative intent surgery at a comprehensive cancer center from 1998 to 2022 in a prospectively collected registry were included. Patients with distant metastasis were excluded. Primary outcome was nodal pathologic complete response (pCR). Downstaging was defined as post-NET decrease in category. RESULTS: We included 123 patients; the majority were cT2 (n = 59) or cT3 (n = 35), and cN0 (n = 81). Median age was 70.0 years (interquartile range 62.1-76.0). Forty-two patients (34.1%) were clinically node-positive. After NET, 73 (59.8%) underwent breast-conserving surgery. All patients underwent sentinel lymph node biopsy, and 12 (9.8%) underwent completion axillary lymph node dissection. In-breast downstaging was achieved in 51 (41.5%) patients, 1 (0.8%) had breast pCR, and 14 (11.4%) had breast upstaging. Axillary downstaging was achieved in 10 (23.8%), 6 patients (14.3%) had nodal pCR, and 14 (33.3%) had axillary upstaging. At 10-year follow-up, local recurrence was 1% and distant recurrence was 14%, while disease-free survival was 82%. After adjusting for demographic and clinical factors, age was the only characteristic associated with mortality (hazard ratio 1.07, 95% confidence interval 1.01-1.13). CONCLUSIONS: In HR+ BC treated with NET, long-term disease-free survival is good, although nodal pCR is uncommon for cN+ patients. Future studies are needed to elucidate optimal neoadjuvant systemic therapy and to delineate oncologically safe strategies to deescalate axillary management for residual microscopic disease.