Post Mastectomy Radiotherapy Is Associated With Improved Survival in Node Positive Male Breast Cancer, a Population Analysis
Menée à partir des données des registres américains des cancers portant sur 1 933 patients masculins atteints d'un carcinome lobulaire ou canalaire non métastatique du sein diagnostiqué entre 1998 et 2013 (âge : 20 ans et plus), cette étude évalue, en fonction du nombre de ganglions lymphatiques atteints et du point de vue du taux de survie globale à 5 ans, l'intérêt d'une radiothérapie après une mastectomie
Purpose : Because of its rarity, there are no randomized trials investigating post mastectomy radiotherapy (PMRT) in male breast cancer. This study retrospectively examines the impact of PMRT in male breast cancer patients in the National Cancer Institute’s Surveillance Epidemiology and End Results (SEER) database. Methods and Materials : The SEER database 8.3.2 was queried for men ages 20+ diagnosed with localized or regional non-metastatic invasive ductal/lobular carcinoma from 1998-2013. Included patients were treated by modified radical mastectomy (MRM), with or without adjuvant external beam radiation. Univariate and multivariate analyses evaluated predictors for PMRT use after MRM. Kaplan-Meier overall survival (OS) curves of the entire cohort and a case-matched cohort were calculated and compared by the log-rank test. Cox-regression was used for multivariate survival analyses. Results : A total of 1933 patients were included in the unmatched cohort. There was no difference in 5 year OS between those who received PMRT and those that did not (78% vs. 77% respectively, p = 0.371), however, in the case-matched analysis, PMRT was associated with improved OS at 5 years (83% vs. 54%, p=<0.001). On subset analysis of the unmatched cohort, PMRT was associated with improved OS in men with 1-3 nodes positive (5 year OS 79% vs. 72% p=0.05) and those with 4+ nodes positive (5 year OS 73% vs. 53% p<0.001). On multivariate analysis of the unmatched cohort, independent predictors for improved OS were use of PMRT HR=0.551 [0.412-0.737] and ER positive disease HR=0.577 [0.339-0.983]. Predictors for a survival detriment were higher grade III/IV HR=1.825 [1.105-3.015], larger tumor T2 HR=1.783 [1.357-2.342] T3/T4 HR=2.683 [1.809-3.978], higher N-stage N1 HR=1.574 [1.184-2.091] N2/N3 HR=2.328 [1.684-3.218], Black race HR=1.689 [1.222-2.336] and older age 81+ HR=4.164 [1.497-11.582]. Conclusions : There may be a survival benefit with the addition of PMRT for male breast cancer with node positive disease.