The recurrence-free survival rates (RFS) after one-stage mastectomy and partial axillary dissection in 1242 low risk breast cancer patients with invasive ductal carcinoma with or without residual cancer tissue (RCT) in the wall of the biopsy cavity were compared. RFS was significantly lower in patients with RCT (RCT-positive) whether premenopausal (n = 416) or postmenopausal (n = 826). By applying the Cox multivariate analysis on RCT and various known prognostic criteria, the incidence rates for RCT-positive patients relative to RCT-negative patients were estimated. The relative risk by RCT-positivity was in the order of 1.45, indicating that RCT is an independent risk factor contributing an increased risk of recurrence of about 45%.