Top Line: Conventional wisdom is to avoid radiating gross disease for localized breast cancer if at all possible.
The Study: This phase 2 trial was designed to upend this decades-long thinking. It enrolled 20 patients with cT1N0 ER+ breast cancer per MRI to receive preoperative ablative radiation of 28.5 Gy in 3 fractions to intact breast tumor. We know, we know, this may seem like a bad idea on its face, as we’ve seen what treating blind to surgical pathology can do. But there were also some reasons this may be beneficial: the thought was treating a small intact tumor would increase target localization and ultimately decrease total target volumes. While the dose may raise eyebrows for an organ where avoiding fibrosis is paramount to the overarching goal of its preservation, the hope was to achieve a complete pathologic response in at least a quarter of women. Interestingly, all patients were treated prone with a prone diagnostic MRI for fusion. Lumpectomy and sentinel node sampling were performed 6-8 weeks after radiation completion. Unfortunately, after all this, there were zero complete pathologic responses, though there were clearly responses with 18 of 20 tumors having <50% tumor cellularity. More unfortunate was that one in 5 women (n=4) had an involved sentinel node and required further whole breast irradiation, and 2 of those 4 had grade 3 breast abscess and grade 3 breast pain. Ultimately 3 of 20 patients had poor to fair cosmesis.
TBL: Not much is gained with this particular strategy of preoperative ablative breast irradiation that requires substantial resources and results in high toxicity when follow-on whole breast irradiation is required.
- Liveringhouse, Int J Radiat Oncol Biol Phys 2023