Clinical outcomes after 1 versus 2-3 lines of neoadjuvant therapy in stage III inflammatory breast cancer

Purpose Many stage III inflammatory breast cancer (IBC) patients experience a sufficient response to first-line (1L) neoadjuvant chemotherapy (NAC) to allow surgery, while some require additional NAC. We evaluated the pathologic complete response (pCR), breast cancer-free survival (BCFS) and overall survival (OS) among patients requiring 1 vs. 2-3 lines (L) of NAC prior to surgery. Methods Stage III IBC patients from 2 institutions who received 1L or 2-3L of NAC prior to surgery were identified. Hormone receptor and HER2 status, grade, and pCR were evaluated. BCFS and OS were evaluated by the Kaplan–Meier method. Multivariable Cox models were utilized to estimate the hazard ratio (HR). Results 808 eligible patients (1997–2020) were identified (median age 51 years, median follow-up 69 months). 733 (91%) had 1L and 75 (9%) had 2-3L of NAC. Grade III, triple-negative and HER2-positive disease were more prevalent in 2-3L patients. 178 (24%) 1L and 14 (19%) 2-3L patients had pCR. 376 1L patients and 41 2-3L patients had recurrences. The 5-year BCFS was worse for the 2-3L group (33 vs. 46%, HR = 1.37; 95% CI 0.99–1.91). However, in 192 patients with a pCR, BCFS was similar (76 vs. 83% in 1L vs. 2-3L, respectively). There were 308 deaths (276 among 1L and 32 among 2-3L patients). The 5-year OS in 1L vs. 2-3L was 60 vs. 53% (HR = 1.32, 95% CI 0.91–1.93). Conclusions Among stage III IBC patients, pCR rates were similar, irrespective of the NAC lines number, and BCFS and OS were comparable with pCR after 1L and 2-3L.