Long-Term Impact of Regional Nodal Irradiation in Patients with Node-Positive Breast Cancer Treated with Neoadjuvant Systemic Therapy
Menée à partir de données portant sur 1 289 patientes atteintes d'un cancer du sein de stade II à III avec métastases axillaires et ayant reçu un traitement systémique néo-adjuvant (durée médiane de suivi : 10,2 ans), cette étude évalue, en fonction du sous-type moléculaire de la tumeur, l'effet d'une irradiation des ganglions régionaux sur le risque de récidive locorégionale et le risque de récidive de la maladie
Background : The impact of regional nodal irradiation (RNI) on locoregional recurrence (LRR) and any disease recurrence (DR) in women with node-positive breast cancer who receive neoadjuvant systemic therapy (NAT) is unknown. Methods : The impact of RNI on LRR and DR was estimated with the cumulative incidence method in 1289 women with stage II-III breast cancer with cytologically confirmed axillary metastases who received NAT, 1989-2007. Multicovariate Cox regression analysis was performed to examine the effect of RNI after accounting for other predictive and prognostic variables. Results : The median follow-up after definitive surgery was 10.2 years. Axillary pCR was observed in 368 of 1289 patients (28.5%). On univariate analysis, axillary pCR reduced 10-year LRR risk from 9.7% to 4.8% (P=.006) and DR risk from 43.0% to 17.0% (P<.001). RNI was administered to 1080 of 1289 patients (83.8%). On univariate analysis, RNI did not affect 10-year LRR risk (no RNI, 9.4%; RNI, 8.1%; P=.62) or DR risk (no RNI, 31.3%; RNI, 36.5%; P=.16). On multicovariate analysis, RNI significantly reduced the risk of LRR (hazard ratio [HR], 0.497; 95% CI, 0.279-0.884; P=.02) and DR (HR, 0.731; 95% CI, 0.541-0.988; P=.04), and showed a particularly strong reduction in risk of DR in patients with HER2+ disease who received trastuzumab (HR, 0.237; 95% CI, 0.109-0.517; P=.0003). A nomogram to predict 10-year LRR risk with and without RNI has been generated to assist clinicians in individualizing treatment decisions based on patient and disease characteristics and response to NAT. Conclusions : Adjuvant RNI reduces risk of LRR and DR in breast cancer patients with axillary metastases who receive NAT across subtypes and particularly decreases the risk of DR in HER2+ breast cancer treated with trastuzumab. Enrollment on the NSABP B-51/RTOG 1304 protocol is encouraged to help determine whether RNI can be omitted in patients with axillary pCR to NAT.