Pract Radiat Oncol. 2025 Oct 18:S1879-8500(25)00224-3. doi: 10.1016/j.prro.2025.09.001. Online ahead of print.
ABSTRACT
PURPOSE: The recently published results of the National Surgical Adjuvant Breast and Bowel Project B51 trial suggest that regional nodal irradiation may be safely omitted in patients with cT1-3N1 breast cancer treated with either lumpectomy or mastectomy, and achieve a pathologic complete response (pCR) in the regional nodes. Of note, almost 80% of patients on the trial demonstrated breast pCR. The goal of our study was to compare clinical outcomes between patients with breast pCR versus not.
METHODS AND MATERIALS: We included all patients treated at a single institution between 2010 and 2021 with cT1-3N1 breast cancer (pathologically proven via fine needle aspiration) who completed neoadjuvant chemotherapy and had axillary nodal pCR. Patients could undergo breast-conserving surgery or mastectomy. Univariate and multivariate logistic models were used to identify factors associated with breast pCR. Cox proportional hazard model was used to find independent prognostic variables associated with disease-free survival (DFS).
RESULTS: We identified 124 patients meeting eligibility criteria. Of those, 72 patients (58%) achieved a breast pCR. On multivariate analysis, patients with human epidermal growth factor receptor (HER2)-positive breast cancer were more likely to develop breast pCR than patients with HER2-negative disease (odds ratio = 15.3; CI, 2.9-156.6; P = .001). At a median follow-up of 5 years, our study showed an overall low rate of local recurrence or distant metastasis with 5-year DFS of 92.3%. There was a numerically higher disease recurrence rate in patients without a breast pCR compared to those with a breast pCR, though this difference was not statistically significant (4.2% vs 12%; hazard ratio = 3.41; 95% CI, 0.53-22.1; P = .2).
CONCLUSIONS: Our study showed that of the 124 patients who had pCR in the nodes, only 58% had a pCR in the breast, which is lower than the 80% rate seen in National Surgical Adjuvant Breast and Bowel Project B51. While our study found no significant difference in 5-year DFS between those with breast pCR versus not, given that patients with ER/PR+/HER2- disease are less likely to achieve breast pCR and tend to recur at later timepoints, further research is needed to evaluate the benefit of regional nodal irradiation in patients with a pCR in the axilla without a pCR in the breast.
PMID:41874497 | DOI:10.1016/j.prro.2025.09.001
