Locoregional Recurrence Risk for Patients With T1,2 Breast Cancer With 1-3 Positive Lymph Nodes Treated With Mastectomy and Systemic Treatment
Menée sur deux cohortes incluant au total 1 027 patientes atteintes d'un cancer du sein de stade T1 ou T2 avec envahissement de 1 à 3 ganglions lymphatiques et traitées entre 1978 et 1997 ou entre 2000 et 2007, cette étude rétrospective évalue l'effet des avancées thérapeutiques sur le bénéfice, en termes de réduction du taux de récidive locorégionale à 5 et 15 ans, d'une radiothérapie après mastectomie et chimiothérapie adjuvante
Purpose : Postmastectomy radiation therapy (PMRT) has been shown to benefit breast cancer patients with 1 to 3 positive lymph nodes, but it is unclear how modern changes in management have affected the benefits of PMRT. Methods and Materials : We retrospectively analyzed the locoregional recurrence (LRR) rates in 1027 patients with T1,2 breast cancer with 1 to 3 positive lymph nodes treated with mastectomy and adjuvant chemotherapy with or without PMRT during an early era (1978-1997) and a later era (2000-2007). These eras were selected because they represented periods before and after the routine use of sentinel lymph node surgery, taxane chemotherapy, and aromatase inhibitors. Results : 19% of 505 patients treated in the early era and 25% of the 522 patients in the later era received PMRT. Patients who received PMRT had significantly higher-risk disease features. PMRT reduced the rate of LRR in the early era cohort, with 5-year rates of 9.5% without PMRT and 3.4% with PMRT (log-rank P=.028) and 15-year rates 14.5% versus 6.1%, respectively; (Cox regression analysis: adjusted hazard ratio [AHR] 0.37, P=.035). However, PMRT did not appear to benefit patients treated in the later cohort, with 5-year LRR rates of 2.8% without PMRT and 4.2% with PMRT (P=.48; Cox analysis: AHR 1.41, P=.48). The most significant factor predictive of LRR for the patients who did not receive PMRT was the era in which the patient was treated (AHR 0.35 for later era, P<.001). Conclusion : The risk of LRR for patients with T1,2 breast cancer with 1 to 3 positive lymph nodes treated with mastectomy and systemic treatment is highly dependent on the era of treatment. Modern treatment advances and the selected use of PMRT for those with high-risk features have allowed for identification of a cohort at very low risk for LRR without PMRT.
International Journal of Radiation Oncology, Biology, Physics 2014