Outcomes after local recurrence following breast-conserving therapy for early-stage breast cancer.

66 Background: Limited data exist for patients who develop local recurrence (LR) following breast conserving therapy (BCT) for early stage breast cancer (ESBC). This study is to evaluate outcomes and predictors of failure following LR in patients treated with BCT. Methods: 1,654 women with ESBC underwent BCT from 1980 – 2013 at a single institution. All patients had breast-conserving surgery followed by whole breast irradiation (WBI) or accelerated partial breast irradiation (APBI). Subset analysis was performed for patients who developed LR as a first event. Clinical outcomes analyzed include contralateral breast failure (CLBF), regional recurrence (RR), distant metastases (DM), cause-specific survival (CSS), and overall survival (OS). Continuous variables were analyzed with an independent samples t-test and categorical variables with χ2. Univariate analysis was performed to determine factors predictive for events after LR. Results: 112 (7%) patients developed LR (87 WBI; 25 APBI), with median time to LR of 6.6 yrs (0.1-28). Median follow-up for the LR group was 14 yrs (0.7-31) overall; 10 (0.7-19) and 16 yrs (1.4-31) for APBI and WBI, respectively (p=0.01). A change from initial to LR pathology was seen for: ER status 21%, PR status 25%, HER2 status 13%, grade 38%, histology 40%, and LVSI 38%. Salvage treatment following LR was mastectomy ± chemotherapy (CHT) in 75%, wide local excision ± RT in 19%, CHT in 2%, and other in 4%. Outcomes following salvage treatment for LR are shown in the table. No differences were seen in outcomes between patients treated with APBI v WBI. Univariate analysis failed to demonstrate any factors predictive for events following LR. Conclusions: Patients who developed LR following BCT for ESBC had excellent clinical outcomes at 5 and 10 yrs, demonstrating effective salvage treatment in this cohort of patients. No differences were noted between patients undergoing APBI v WBI. Further identification of histopathologic patterns between first cancer and LR is currently underway. [Table: see text]