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September 2019: Impact of post-mastectomy radiotherapy (RT) after neoadjuvant chemotherapy (NACT) on survival in breast cancer patients

27.09.2019

Results of a retrospective pooled analysis from three randomized neoadjuvant GBG trials (GeparTrio, GeparQuattro and GeparQuinto) evaluating the impact of post-mastectomy RT (PMRT) after NACT on survival in breast cancer patients have been published in the Annals of Surgical Oncology.

The impact of locoregional RT after NACT and mastectomy in breast cancer patients is currently unclear. The aim of this study was to analyze the impact of adjuvant PMRT on locoregional recurrence (LRR) and survival in breast cancer patients. A retrospective pooled analysis from three prospective randomized GBG trials (GeparTrio, GeparQuattro and GeparQuinto) investigating different NACT regimens was performed. A total of 6139 patients were treated in these trials from September 2002 to July 2010. Of them, 817 patients with non-inflammatory breast cancer who underwent mastectomy after NACT had available information on the use of RT and were included in the pooled analysis.

The 5-year cumulative incidence of (LRR) was 15.2% (95%CI 9.0-22.8%) in patients treated without RT and 11.3% in those treated with RT (95%CI 8.7-14.3%). Multivariate analysis showed that the RT was associated with a lower risk of LRR (HR 0.51 [95%CI 0.27-1.0]; p=0.05). This effect was observed especially in patients with cT3/4 tumors (HR 0.40 [95%CI 0.17-0.94]; p=0.04) as well as in patients who were cN-positive before NACT (HR 0.39 [95%CI 0.19-0.83]; p=0.01), including those who converted to ypN0 after NACT (HR 0.19 [95% CI 0.04-0.97]; p=0.05). Overall, the disease-free survival (DFS) was significantly worse in patients who received RT in bivariate but not in multivariate analyses (HR 1.48 [95%CI 1.01-2.18]; p=0.04 and HR=1.14 [95%CI 0.75-1.73; p=0.55, respectively). Patients who were cN-negative at diagnosis and received RT had a significantly worse DFS (HR 3.4 [95%CI 1.46-7.91]; p=0.01). In all other multivariate subgroup analyses, RT was not significantly associated with DFS. These results suggest that RT decreased the risk of LRR in breast cancer patients who received a mastectomy after NACT without an improvement in DFS.

Krug D, Lederer B, Seither F, Nekljudova V, Ataseven B, Blohmer JU, Costa SD, Denkert C, Ditsch N, Gerber B, Hanusch C, Heil J, Hilfrich J, Huober JB, Jackisch C, Kümmel S, Paepke S, Schem C, Schneeweiss A, Untch M, Debus J, von Minckwitz G, Kühn T, Loibl S. Post-Mastectomy Radiotherapy After Neoadjuvant Chemotherapy in Breast Cancer: A Pooled Retrospective Analysis of Three Prospective Randomized Trials.
Ann Surg Oncol. 2019 Jul 26; doi: 10.1245/s10434-019-07635-x.

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