Long-term Survival Outcomes Following Internal Mammary Node Irradiation in Stage II-III Breast Cancer: Results of a Large Retrospective Study With 12-Year Follow-up
Menée sur 396 patientes atteintes d'un cancer du sein de stade II-III traité par mastectomie puis radiothérapie entre 1994 et 2002 (durée médiane de suivi : 149 mois), cette étude rétrospective évalue, du point de vue de la survie sans maladie et de la survie globale, l'intérêt d'ajouter au traitement une radiothérapie de la chaîne ganglionnaire mammaire interne
Purpose : To examine the effect of internal mammary node irradiation (IMNI) on disease-free survival (DFS) and overall survival (OS) in breast cancer patients treated with modified radical mastectomy and postoperative radiation therapy. Methods and Materials : Between 1994 and 2002, 396 patients with stage II-III breast cancer were treated with postmastectomy radiation therapy with (n=197) or without (n=199) IMNI. Patients who received neoadjuvant chemotherapy were excluded. IMNI was administered at the clinical discretion of the treating physician. Median RT dose was 50.4 Gy (range, 45.0-59.4 Gy) in 28 fractions, with inclusion of the supraclavicular fossa in 96% of patients. Adjuvant chemotherapy was administered to 99.7% of the patients and endocrine therapy to 53%. Results : The median follow-up was 149 months (range, 124-202). IMNI patients had more advanced nodal stage and non-high grade tumors than those without IMNI (P<.001). Otherwise, disease and treatment characteristics were well balanced. The 10-year DFS with and without IMNI was 65% and 57%, respectively (P=.05). Multivariate analysis demonstrated that IMNI was an independent, positive predictor of DFS (hazard ratio [HR], 0.70; P=.02). Benefits of IMNI in DFS were seen most apparently in N2 patients (HR, 0.44; 95% confidence interval [CI], 0.26-0.74) and inner/central tumors (HR, 0.55; 95% CI, 0.34-0.90). The 10-year OS with and without IMNI was 72% and 66%, respectively (P=.62). The 10-year DFS and OS were 61%, and 69%, respectively. Conclusions : Internal mammary node irradiation significantly improved DFS in postmastectomy breast cancer patients. Pending long-term results from randomized trials, treatment of internal mammary nodes should be considered in postmastectomy radiation therapy.
International Journal of Radiation Oncology, Biology, Physics