Prognostic Outcomes by Axillary Approach in Lobular and Ductal Breast Cancer With Sentinel Node Macrometastases: A Retrospective Cohort Study.

Abstract

Purpose: To compare survival outcomes between patients with invasive lobular carcinoma (ILC) and invasive ductal carcinoma non-special type (NST) presenting with sentinel lymph node biopsy (SLNB)-detected macrometastases in early-stage breast cancer.

Materials and methods: A retrospective cohort study was conducted including 364 cN0 breast cancer patients with SLNB-detected macrometastases who underwent surgical treatment between July 2011 and December 2023. Patients were categorized as NST (n = 250) or ILC (n = 108). SLNB was the primary axillary staging procedure, with axillary lymph node dissection (ALND) performed according to predefined clinical criteria. Univariate and multivariate Cox regression analyses were used to identify predictors of pN2-pN3. Survival outcomes were assessed using Kaplan-Meier curves and compared with log-rank tests.

Results: ILC patients presented with larger tumors, higher rates of multifocality, and greater axillary nodal involvement compared to NST. Surgery was more frequently mastectomy and ALND. pN2-N3 was identified in 12% of cases, with pT3 stage, ILC histology, and lymphovascular invasion as independent predictors. After a median follow-up of 7.6 years, the ILC group exhibited higher overall mortality (19.4% vs. 9.6%) and deaths attributed to systemic progression (57% vs. 29%). Ten-year distant disease-free survival and breast cancer-specific survival were significantly lower in the ILC cohort (63% vs. 87% and 65% vs. 93%, respectively; P < .05). Although 10-year overall survival was lower in ILC (54% vs. 79%), statistical significance was only observed in patients with advanced nodal disease (pN2-N3).

Conclusions: ILC is associated with more advanced axillary burden and significantly worse long-term oncologic outcomes compared to NST carcinoma when macrometastases are present at SLNB.