Impact of multicentricity on clinical outcome in patients with T1-2, N0-1, M0 breast cancer

Background: The objective was to determine the impact of multicentric breast cancer on recurrence and survival and to evaluate the current tumor, node, metastasis staging system recommendations for multicentricity in the breast. Methods: This study included 284 nonpregnant patients with T1-2, N0-1, M0 breast cancer, without previous cancer, who were treated by modified radical mastectomy followed by doxorubicin-based adjuvant chemotherapy. Clinical and pathological data were collected retrospectively and survival was calculated from the date of initial diagnosis using the Kaplan-Meier method. Results: The median follow-up time was 8 years (range, 0.3-24.0), and the median age was 47 years (range, 23-76). The median clinical size of the index tumor was 2.5 cm. In 17% of patients, the clinical nodal status was N1. In 84% of patients, pathology of the index lesion was invasive ductal +/- in situ. Multicentric breast cancer was detected in 60 patients (21%): 30 patients with two lesions, 13 patients with three lesions, and 17 patients with four or more lesions. Locoregional recurrence, contralateral breast cancer, distant metastasis, and survival (disease-specific and disease-free) were similar in both groups of multicentric versus unicentric breast tumors. There was a significant difference between groups in estrogen receptor and axillary lymph node positivity, but these did not contribute significantly to outcome on multivariate analysis. Conclusions: Multicentricity does not increase the risk of poor outcomes in patients with early-stage breast cancer. This supports the current recommendations of the tumor, node, metastasis staging system that tumor size should be based on the diameter of the largest lesion in patients with multicentric breast cancer.