Rates of Pathologic Complete Response and Overall Survival in Patients with Inflammatory Breast Cancer: A National Cancer Database Study.

Abstract

Patients with inflammatory breast cancer (IBC) have worse survival compared with stage III non-IBC matched cohorts; however, the prognostic significance of achieving pathologic complete response (pCR) in the setting of IBC is not well described. We evaluated overall survival (OS) between IBC patients and non-IBC patients who achieved pCR. Adult females diagnosed in 2010-2018 with clinical prognostic stage III unilateral invasive breast cancer treated with neoadjuvant chemotherapy (NAC) followed by surgery were selected from the National Cancer Database. Unadjusted OS from surgery was estimated using the Kaplan-Meier method, and log-rank tests were used to compare groups. Cox proportional hazard models were used to estimate the association of study groups with OS after adjustment for available covariates. The study included 38,390 patients; n=4600 (12.0%) IBC and n=33,790 (88.0%) non-IBC. Overall pCR rates were lower for IBC compared with non-IBC (20.7% vs. 23.3%; p<0.001). Among those achieving pCR, 5-year mortality was higher for IBC patients (16.4%, 95% confidence interval [CI] 13.9-19.1%) versus non-IBC patients (9.1%, 95% CI 8.4-9.8%; log-rank p<0.001). Among all patients achieving pCR, IBC remained associated with worse OS compared with non-IBC (hazard ratio 1.48, 95% CI 1.19-1.85; p<0.001). We found a lower pCR rate and worse OS in IBC patients compared with non-IBC stage III patients. Despite effective systemic therapies, achieving a pCR for IBC patients may not carry the same prognostic impact compared with non-IBC stage III patients.