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Top Line: The role of post-mastectomy radiation (PMRT) for breast cancer with limited nodal metastases may always remain controversial.
The Study: Until (and probably after) the results of trials like NSABP B-51, SUPREMO, and TAILOR-RT are available, we’ll continue to rely on data from large cohorts. Here we have a multi-center, retrospective study from China describing outcomes with or without PMRT in over 1800 patients from 12 centers who received mastectomy following modern neoadjuvant chemo for cT1-4N1-2 breast cancer between 2000 and 2014. The majority (71%) received a neoadjuvant anthracycline / taxane regimen. PMRT was commonly indicated for ypN+ disease and for ypN- disease with high risk features like age <50, cT3/4 disease, cN2 disease, or negative hormone receptor status. Important caveats to the “modernity” of this trial were the widespread use of 2D-planning and omission of internal mammary node coverage. Overall, 70% of patients received PMRT: 47% of ypN0 patients, 67% of ypN1 patients, and 87% of ypN2 patients. Obviously, patients who received PMRT had higher risk features than those who did not. Either with or without propensity matching, the benefit of PMRT matched the extent of nodal disease. Local control was improved with PMRT for ypN0 disease, both local control and disease-free survival (DFS) were improved for ypN1, and those plus overall survival were improved for ypN2 disease.
TBL: To no big surprise, this large series of patients receiving mostly modern neoadjuvant chemo confirms the benefit of PMRT is strongly tied to the extent of residual nodal disease. | Huang, Int J Radiat Oncol Biol Phys 2020