Abstract P3-13-09: Increased mortality with repeat lumpectomy alone after ipsilateral breast tumor recurrence: A propensity-adjusted, population-based SEER analysis

Background: The benefit of repeat lumpectomy for ipsilateral breast tumor recurrence (IBTR) after breast conserving surgery (BCS) is currently inconclusive. This issue has become even more important as small and isolated recurrent tumors were frequently diagnosed. Methods: IBTR patients with definitive surgery were identified in the Surveillance, Epidemiology, and End Results registry between 1973 and 2013. The effect of different IBTR surgeries on overall and cancer-specific mortality was assessed using risk-adjusted Cox proportional hazard regression modeling and stratified propensity score matching analysis (PSMA). Results: Based on the selection criteria, 5098 patients were recruited. Of those, 4048 (79.4%) women underwent mastectomy and 1050 (20.1%) underwent repeat lumpectomy after IBTR. Patients who received repeat lumpectomy had lower grade (23.7% vs 15% for well-differentiated) and smaller recurrent tumor (47% vs 36.2% for ≤ 1 cm) but earlier recurrence (23.9% vs 11.2% for interval times < 48 months) than those who underwent mastectomy. A minority of each group (24.7% of those undergoing repeat lumpectomy and 3% of the mastectomy group) underwent RT after surgery. In multivariable Cox regression analysis, repeat lumpectomy was associated with increased overall mortality (Hazard ratio (HR) = 1.58, 95% CI = 1.353 to 1.844, P < 0.001) and cancer-specific mortality (HR = 1.721, 95% CI = 1.345 to 2.202, P< 0.001). Similar HRs were derived from the PSMA cohort. However, we found no significant difference in overall mortality for women who underwent repeat lumpectomy followed by RT compared with that for those who underwent mastectomy (P= 0.411). Moreover, IBTR patients with small tumors (≤ 1 cm) who underwent repeat lumpectomy with RT rather than without had similar overall and cancer-specific survival rates to those who underwent mastectomy (P= 0.189 and P= 0.604, respectively). Conclusions: Our investigation suggests that compared with mastectomy, repeat lumpectomy for IBTR is associated with higher overall and cancer-specific mortality under real-world observational conditions. Furthermore, repeat lumpectomy with RT is equivalent to mastectomy with respect to overall mortality and may influence treatment decision making for patients with small IBTR. Citation Format: Su Y, Guo R, Xue J, Chi Y, Wu J. Increased mortality with repeat lumpectomy alone after ipsilateral breast tumor recurrence: A propensity-adjusted, population-based SEER analysis [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P3-13-09.