ABSTRACT Background and Objectives Neoadjuvant chemoimmunotherapy (NACI) for node‐positive breast cancer may induce immune cell activation in regional lymph nodes (LN), confounding post‐NACI imaging. Here we evaluated RECIST 1.1 criteria to predict post‐NACI pathologic LN status. Methods We studied patients with biopsy‐proven cN+ non‐distant metastatic breast cancer receiving NACI operated on 03/2020–09/2024 with both pre‐ and post‐NACI cross‐sectional imaging. Per RECIST 1.1, LN short axis diameter (SAD) was measured in target (defined as SAD ≥ 15 mm) and nontarget (SAD 10–14.9 mm) LNs. Groups were compared using Fisher′s exact test. Results 75 patients, median age 53 years, were studied: 61% cN1, 12% cN2, and 27% cN3. Baseline median number of imaging‐suspicious LN was 4 (IQR 2‐5). Post‐NACI, 64% had a nodal pathologic complete response (pCR/ypN0). 55% met RECIST 1.1 LN assessment criteria. 21 of 32 (66%) with an imaging CR (iCR) were ypN0, while 8 of 9 (89%) without an iCR were ypN0. Neither target ( p = 0.24) nor combined target/nontarget LN iCR ( p = 0.76) predicted ypN status. Nodal pCR rates were higher in those with ≤ 1 versus > 1 suspicious LN post‐NACI (71% vs. 42%, p = 0.03). Conclusions RECIST 1.1 criteria did not predict nodal pCR for NACI‐treated node‐positive breast cancer patients. Other post‐NACI imaging assessment strategies are needed.
Redaelli et al. (Wed,) studied this question.