72236 - Tumor Localization within the breast is an Independent Factor for Sentinel Lymph Node Positivity in Breast Cancer

Introduction Sentinel lymph node (SLN) biopsy is the current standard for prognostication and guiding therapeutics in early breast cancer. Recent level I evidence suggests that omitting up-front axillary surgery in select low-risk patients is oncologically safe. The relevance of identifying clinicopathological factors in guiding the selection of patients at low risk for SLN metastasis cannot be understated. Limited evidence exists regarding the capacity of tumor localization within the breast as a risk factor for SLN metastasis. This study aims to evaluate whether the localization of the primary breast cancer predicts SLN status. Method We conducted a retrospective study of consecutive patients with stage I-III primary breast cancer undergoing up-front breast surgery and SLN biopsy between 2003 and 2008 at Sahlgrenska University Hospital, Sweden. Multivariable logistic regression analysis was used to identify independent predictive factors for sentinel node positivity. Result A total of 1231 clinically node-negative patients were identified with a mean age of 60 years. The majority of tumors measured ≤5 cm (n=1159, 94%) and exhibited estrogen receptor positivity (n=1079, 88%). Unifocal cancers, lower grade, T1-2 size and localization within the breast showed a significant correlation with SLN negative status (p<0.05). Multivariable logistic regression identified increasing age and tumour size, tumor localization in the lower outer and upper inner quadrants as independent factors for SLN metastasis (p<0.05) (Table 1). Discussion Tumor localization within the breast is an independent risk factor for SLN metastasis. The location of breast cancer is a clinical parameter worthy of consideration for selecting patients for axillary surgery de-escalation.