Mastectomy is still considered the treatment of first choice in patients with ipsilateral breast tumor recurrence (IBTR) after breast-conserving surgery (BCS) and whole-breast radiotherapy.

We retrospectively evaluated 161 patients with invasive IBTR who underwent a second BCS in order to describe prognosis, determine predictive factors of outcome, and select the subset of patients with the best local control. Median follow-up after IBTR was 81 months.

Median age at IBTR was 53 years. Five-year overall survival after IBTR was 84 % (95 % confidence interval [CI] 78-89). Five-year cumulative incidence of a second local event after IBTR was 29 % (95 % CI 22-37). At the multivariate analysis, IBTR size >2 cm and time to relapse ≤48 months significantly increased the risk of local reappearance (hazard ratio [HR] 3.3, 95 % CI 1.6-7.0; and HR 1.9, 95 % CI 1.1-3.5). The 5-year cumulative incidence of a further local reappearance of the tumor after repeating BCS was 15.2 % in the patients with IBTR ≤2 cm and time to IBTR >48 months, 31.2 % in the patients with IBTR ≤2 cm and time to IBTR ≤48 months, and 71.2 % in patients with IBTR >2 cm (P < 0.001).

The best candidates for a second BCS are those with small (≤2 cm) and late (>48 months) IBTR. The information about the risk of a further local reappearance after repeating BCS should be shared with the patients in the decision making process.