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Top Line: Recently we learned about the ARTIC genomic classifier that predicts locoregional recurrence risk (LRR) and benefit of breast-only radiation in women with early-stage N0 breast cancer.
The Study: Unfortunately this did nothing to secure the forever-swinging controversy of regional nodal irradiation (RNI) in women with N1 disease, with the pendulum currently resting on heavy RNI use following the MA.20 and EORTC 22922 trials. The problem is enrollees were all over the map. Heck, one can come up with clinical scenarios (e.g., stage I medial tumor) that could have been included on both the RNI and the radiation omission trials. While we’re awaiting results from ongoing trials such as MA.39 looking at RNI omission for low Oncotype recurrence score (RS), we have studies like this one. It retrospectively analyzed tissue among post-menopausal women with hormone receptor(+) N+ breast cancer enrolled on the SWOG S8814 trial. Overall, those with a low RS (<18) had a lower 10-year LRR rate (10%) compared to those with intermediate or high RS (17%). A large proportion had mastectomy without radiation, and RS remained a predictor of 10-year LRR (8% vs 17%), even among the subset who had 1-3 positive nodes (<2% vs 11%). Unfortunately, since the trial compared systemic therapies, there's no real info on radiation interaction with Oncotype RS (i.e., no real info on whether RS predicts a benefit with radiation), though one may assume the persistent relative risk reduction seen through the decades.
TBL: Among women with hormone receptor(+), N+ breast cancer, Oncotype recurrence score is associated with risk of locoregional recurrence, even among women with N1 disease treated with mastectomy. | Woodward, JAMA Oncol 2020