Long-Term Impact of Regional Nodal Irradiation in Patients with Node-Positive Breast Cancer Treated with Neoadjuvant Systemic Therapy

Publication date: Available online 19 June 2018
Source:International Journal of Radiation Oncology*Biology*Physics
Author(s): Shane R. Stecklein, Minjeong Park, Diane D. Liu, Janeiro J. Valle Goffin, Abigail S. Caudle, Elizabeth A. Mittendorf, Carlos H. Barcenas, Sarah Mougalian, Wendy A. Woodward, Vicente Valero, Aysegul A. Sahin, Wei T. Yang, Simona F. Shaitelman
BackgroundThe 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.MethodsThe 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.ResultsThe 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.ConclusionsAdjuvant 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.



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