The objective of this study was to evaluate the influence of pathologic factors other than tumor size and number of involved axillary nodes on the risk of locoregional recurrence (LRR) following mastectomy.

We reviewed the medical records of 1031 patients treated with mastectomy and doxorubicin-based chemotherapy without radiation on 5 prospective clinical trials. Median follow-up was 116 months (range, 6-262 months).

Patients with gross multicentric disease were at increased risk of LRR (37% at 10 years). However, patients with multifocal disease and those with microscopic multicentric disease did not experience higher rates of LRR than those with single lesions (17% at 10 years). Patients with lymph-vascular space invasion (LVSI) or involvement of the skin or nipple also experienced high rates of LRR (25%, 32%, and 50%, respectively). The presence of close (<5 mm) or positive margins was associated with an increased risk of LRR (45%). The increased risk of LRR observed for patients with pectoral fascial invasion (33%) was not reduced when negative deep margins were obtained. On multivariate analysis, the presence of 4 or more involved axillary nodes, tumor size of greater than 5 cm, close or positive surgical margins, and gross multicentric disease were found to be independent predictors of LRR (all, p < 0.01). In a separate analysis including only patients with 1-3 involved axillary nodes, microscopic invasion of the skin or nipple, pectoral fascial invasion, and the presence of close or positive margins were significant predictors of LRR.

In addition to the extent of primary and nodal disease, other factors that predict for high rates of LRR include the presence of LVSI, involvement of the skin, nipple or pectoral fascia, close or positive margins, or gross multicentric disease. These factors predict for high LRR rates regardless of the number of involved axillary nodes.