Second Conservative Treatment for Local Recurrence Breast Cancer: A GEC-ESTRO Oncological Outcome and Prognostic Factor Analysis.

PURPOSE: For second ipsilateral breast tumor event (2nd IBTE), second conservative treatment (2nd CT) combining lumpectomy plus accelerated partial breast reirradiation (APBrI) represents a curative option. The aim of this study was to analyze oncological prognostic factors for patients with a 2nd IBTE treated with 2nd CT. METHODS AND MATERIALS: An analysis of clinical practices was conducted across 7 academic hospitals/cancer centers in 6 European countries based on the GEC-ESTRO database. Patients presenting a 2nd IBTE occurring after conservative surgery (lumpectomy + axillary evaluation) and irradiation performed for the primary tumor underwent a 2nd CT with brachytherapy-based APBrI. The main outcome was 5-year cumulative incidence (CI) rate of second local relapse. All analyzed patients were classified according to risk groups for Groupe Européen de Curiethérapie-European Society for Therapeutic Radiology and Oncology (GEC-ESTRO) accelerated partial breast irradiation (APBI) and molecular classification and time interval between first and second breast surgery (TIS1S2). Finally, we combined GEC-ESTRO APBI, molecular, and TIS1S2 risk groups, leading to the definition of a new score (named TAM: score based on the combination of time interval [T] between first and second surgery and APBI [A] and molecular [M] classifications) specifically designed for 2nd IBTE oncological outcome analysis. RESULTS: From July 1994 to January 2021, a total of 508 patients received a 2nd CT. At the time of 2nd IBTE, median age was 64.6 years (range, 56.2-72.6). With a median follow-up of 60.9 months (56.2-72.6), the 5-year second local relapse CI rate was 4% (95% confidence interval [95% CI], 2%-6%). The 5-year distant metastasis disease CI rate was 7% (95% CI, 4%-10%). Five-year disease-free and overall survival rates were 89% (95% CI, 86%-93%) and 91% (95% CI, 88%-94%), respectively. In multivariate analysis, TAM score was an independent prognostic factor for all the oncological items (P < .001) except disease-specific survival (P = .07) and overall survival (P = .09). The grade ≥3 late toxicity rate was 12.1%. CONCLUSIONS: This analysis of 2nd CT combining lumpectomy with APBrI for 2nd IBTE confirmed the excellent oncological results obtained after 2nd CT. Furthermore, the GEC-ESTRO TAM score appears to be an important prognostic factor, assisting patients and physicians in the decision-making process.

Salvage Mastectomy Versus Second Conservative Treatment for Second Ipsilateral Breast Tumor Event: A Propensity Score-Matched Cohort Analysis of the GEC-ESTRO Breast Cancer Working Group Database.

PURPOSE: Second conservative treatment has emerged as an option for patients with a second ipsilateral breast tumor event after conserving surgery and breast irradiation. We aimed to address the lack of evidence regarding second breast event treatment by comparing oncologic outcomes after conservative treatment or mastectomy. METHODS AND MATERIALS: Oncologic outcomes were analyzed using a propensity score-matched cohort analysis study on patients who received a diagnosis of a second breast event between January 1995 and June 2017. Patient data were collected from 15 hospitals/cancer centers in 7 European countries. Patients were offered mastectomy or lumpectomy plus brachytherapy. Propensity scores were calculated with logistic regression and multiple imputations. Matching (1:1) was achieved using the nearest neighbor method, including 10 clinical/pathologic data related to the second breast event. The primary endpoint was 5-year overall survival from the salvage surgery date. Secondary endpoints were 5-year cumulative incidence of third breast event, regional relapse and distant metastasis, and disease-free and specific survival. Complications and 5-year incidence of mastectomy were investigated in the conservative treatment cohort. RESULTS: Among the 1327 analyzed patients (mastectomy, 945; conservative treatment, 382), 754 were matched by propensity score (mastectomy, 377; conservative treatment, 377). The median follow-up was 75.4 months (95% confidence interval [CI], 65.4-83.3) and 73.8 months (95% CI, 67.5-80.8) for mastectomy and conservative treatment, respectively (P = .9). In the matched analyses, no differences in 5-year overall survival and cumulative incidence of third breast event were noted between mastectomy and conservative treatment (88% [95% CI, 83.0-90.8] vs 87% [95% CI, 82.1-90.2], P = .6 and 2.3% [95% CI, 0.7-3.9] vs 2.8% [95% CI, 0.8-4.7], P = .4, respectively). Similarly, no differences were observed for all secondary endpoints. Five-year cumulative incidence of mastectomy was 3.1% (95% CI, 1.0-5.1). CONCLUSIONS: To our knowledge, this is the largest matched analysis of mastectomy and conservative treatment combining lumpectomy with brachytherapy for second breast events. Compared with mastectomy, conservative treatment does not appear to be associated with any differences in terms of oncologic outcome. Consequently, conservative treatment could be considered a viable option for salvage treatment.