Does RECIST 1.1 Predict Nodal Response to Neoadjuvant Chemo-Immunotherapy in Breast Cancer?
Matteo Redaelli1, Jessica A Steadman1, Tanya L Hoskin2
1Department of Surgery, Division of Breast and Melanoma Surgical Oncology, Rochester, Minnesota, USA.
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.
