Abstract P4-12-04: Breast cancer subtype, age and lymph node status as predictors of local recurrence following breast-conserving therapy

Abstract Purpose/Objectives: Advances in breast-conserving therapy (BCT) have yielded local control rates comparable or superior to those of mastectomy. Here, we sought to identify risk factors associated with isolated local recurrence (LR) following BCT. Materials/Methods: This study included a multi-institutional cohort of 2,233 consecutive breast cancer patients who underwent BCT between 1998 and 2007. Patient characteristics and disease parameters were stratified by age, subtype and nodal status. Biologic subtype was approximated by receptor status and tumor grade. No patients received HER2/neu-directed therapy. The association of clinicopathologic features with LR was evaluated using Cox proportional hazards regression models. Results: At a median follow-up of 106 months, 69 LR events (3.1%) were observed. Among the overall cohort, 10-year freedom from LR was 95.9%. On univariate Cox regression analysis, risk factors associated with LR included subtype other than luminal A (hazard ratio [HR] for luminal B = 3.01, HER2 = 6.29, triple negative [TNBC] = 4.72; p<0.001 for each), younger age (HR of oldest versus youngest quartile = 0.43; p=0.005), regional lymph node involvement (HR for 4-9 involved nodes = 3.04; >9 nodes = 5.82; p<0.01 for each), positive resection margins (HR = 2.43; p=0.005), and high-grade disease (HR = 5.37; p <0.001). Presence of LVI (HR = 1.56; p=0.06) or 1-3 involved nodes (HR = 1.55; p=0.07) approached significance. Multivariate Cox regression demonstrated an association with LR among those with non-luminal A subtypes (HR for luminal B = 2.64, HER2 = 5.42, TNBC = 4.32; p<0.001 for each), younger age (HR for age >50 = 0.56; p=0.01), and any nodal disease (HR=1.06 per involved node; p<0.004). Conclusions: BCT yields favorable outcomes for the large majority of patients, although increased LR was observed among those with non-luminal A subtypes, younger age, and increasing lymph node involvement. Risk factors for LR following BCT appear to be converging with those following mastectomy in the current era. Citation Format: Braunstein LZ, Taghian AG, Niemierko A, Salama L, Capuco A, Wong JS, Punglia RS, Bellon JR, MacDonald SM, Harris JR. Breast cancer subtype, age and lymph node status as predictors of local recurrence following breast-conserving therapy [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P4-12-04.