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.

Significant Correlation Between Overall Survival and Mean Lung Dose in Lung Stereotactic Body Radiation Therapy (SBRT).

BACKGROUND: After stereotactic body radiation therapy (SBRT) for medically inoperable stage I non-small-cell lung cancer (NSCLC), more patients die of comorbidities, particularly severe pulmonary insufficiency, than of tumor progression. The aim of this study was to evaluate correlation between lung biologically effective dose (BED) with an α/ß ratio of 3 Gy (BED3) and overall survival (OS) for these patients. METHODS: From 2012 to 2017, we have developed a prospectively updated institutional database for all first 100 consecutively treated patients with inoperable Stage 1 (T1T2N0M0) NSCLC. All SBRT were conducted on a Novalis Tx® LINAC with two coplanar dynamic conformal arcs (84%) or with coplanar volumetric modulated arc therapy (VMAT) (16%). Mean GTV and PTV were 8.6 cc and 50.8 cc, respectively. The marginal dose prescribed to the PTV was the 80% isodose line (IDL), i.e., 54 Gy in 3 fractions for 76 patients (BED10 = 126 Gy) and 50 Gy in 5 fractions for 24 patients (BED10 = 83.3 Gy). Pulmonary heterogeneity has been taken into account by using Monte Carlo or AAA algorithms. Median follow-up was 25 months. RESULTS: At 1, 2, 3 and 5 years, local control (LC) was respectively 100, 98.2, 98.2, and 77.7%, and OS was respectively 83, 71.2, 58.1, and 33.2% (median OS was 49 months). Significant OS prognostic factors in univariate and multivariate analysis were mean lung BED3 (HR = 1.14, p = 0.01) and PTV volume (HR = 1.01, p = 0.004). A mean lung BED3 ≤ 5 Gy was significantly associated with a doubling of median OS from 29 months to more than 60 months (not achieved, p = 0.0068). For patients with a forced expiratory volume in 1 second (FEV1) ≤ 40%, a mean lung BED3 ≤ 4 Gy was significantly associated with a doubling of median OS from 23 to 46 months (p = 0.019). CONCLUSION: Mean lung BED3 is strongly and significantly associated with OS in SBRT for inoperable Stage I NSCLC. For all treated patients, a mean lung BED3 ≤ 5 Gy lead to a doubling of median OS. This threshold value should be reduced to 4 Gy for patients with FEV1 ≤ 40%.