Having ypN0 may not be enough to abandon the Postmastectomy Radiotherapy (PMRT) in Her-2 positive patients

We read Saifi and colleagues' article with great excitement. In the article, the authors argue that post-mastectomy radiotherapy (PMRT) may not be necessary for patients who achieve a pathological complete response at the axilla (ypN0) with neoadjuvant chemotherapy including anti-Her-2 therapy, as it does not contribute to local–regional control[ [1] Saifi O. Bachir B. Panoff J. et al. Post-mastectomy Radiation Therapy in HER-2 Positive Breast Cancer after Primary Systemic Therapy: Pooled Analysis of TRYPHAENA and NeoSphere Trials. Radiotherapy and Oncology. 2023; https://doi.org/10.1016/j.radonc. 2023.109668 Crossref Google Scholar ]. Moreover, the study's significance is underscored by demonstrating that the combination of PMRT and appropriate systemic therapy effectively decreases locoregional recurrence (LRR) in at least the ypN+-positive subgroup of Her-2-positive patients, who represent one of the most resistant patient populations to radiotherapy in the absence of anti-Her-2 therapy[ 1 Saifi O. Bachir B. Panoff J. et al. Post-mastectomy Radiation Therapy in HER-2 Positive Breast Cancer after Primary Systemic Therapy: Pooled Analysis of TRYPHAENA and NeoSphere Trials. Radiotherapy and Oncology. 2023; https://doi.org/10.1016/j.radonc. 2023.109668 Crossref Google Scholar , 2 Breslin T. Edge S.B. Hassett M.J. Punglia R.S. Biological Subtype Predicts Risk of Locoregional Recurrence After Mastectomy and Impact of Postmastectomy Radiation in a Large National Database. Int J Radiat Oncol Biol Phys. 2015 Nov 1; 93: 622-630https://doi.org/10.1016/j.ijrobp.2015.07.006 Abstract Full Text Full Text PDF Scopus (66) Google Scholar ]. However, we believe that reporting the details of radiation therapy fields would be beneficial, as the regional recurrences occur in approximately half of the patients in the supraclavicular region. In the EORTC study, which also included N0 patients, adjuvant lymphatic radiotherapy demonstrates a significant improvement in metastasis-free survival in the first decade and ultimately led to a decrease in breast cancer-specific mortality at the 15-year mark[ 3 Poortmans P.M. Collette S. Kirkove C. et al. EORTC Radiation Oncology and Breast Cancer Groups. Internal Mammary and Medial Supraclavicular Irradiation in Breast Cancer. N Engl J Med. 2015 Jul 23; 373: 317-327https://doi.org/10.1056/NEJMoa1415369 Crossref PubMed Scopus (740) Google Scholar , 4 Poortmans P.M. Weltens C. Fortpied C. et al. European Organization for Research and Treatment of Cancer Radiation Oncology and Breast Cancer Groups. Internal mammary and medial supraclavicular lymph node chain irradiation in stage I-III breast cancer (EORTC 22922/10925): 15-year results of a randomized, phase 3 trial. Lancet Oncol. 2020 Dec; 21: 1602-1610https://doi.org/10.1016/S1470-2045(20)30472-1 Abstract Full Text Full Text PDF PubMed Scopus (113) Google Scholar ]. It may also be better to learn distant metastasis-free survival data of Saifi’s trial[ [1] Saifi O. Bachir B. Panoff J. et al. Post-mastectomy Radiation Therapy in HER-2 Positive Breast Cancer after Primary Systemic Therapy: Pooled Analysis of TRYPHAENA and NeoSphere Trials. Radiotherapy and Oncology. 2023; https://doi.org/10.1016/j.radonc. 2023.109668 Crossref Google Scholar ].