BACKGROUND AND PURPOSE There is limited retrospective evidence addressing the utility of post-mastectomy radiotherapy (PMRT) in patients with T3N0 breast cancer. We performed a retrospective analysis of the National Cancer Database (NCDB) comparing overall survival (OS) in T3N0 patients treated with mastectomy alone (MTX) or with PMRT. MATERIALS AND METHODS We performed a matched-cohort analysis of NCDB breast cancer patients with pT3N0 disease who did not receive NAC, or cT3N0 patients who received NAC treated between 2006 and 2014. Patients were matched for all available baseline characteristics using propensity scores with inverse probability of treatment weighting (IPTW) with stabilized weights. RESULTS We identified 13,901 eligible patients. In the pT3N0 cohort, median follow-up was 47 months for the MTX group and 50 months for the PMRT group. In the cT3N0 cohort, median follow-up was 44 months for the MTX group and 46 months for the PMRT group. OS was higher in pT3N0 patients treated with PMRT compared to MTX: 7-year OS of 74% vs. 65% (P < 0.001). Doubly robust multivariable analysis showed an association between PMRT and improved OS (HR 0.78, 95% CI 0.68-0.89, P < 0.001). There was no benefit to PMRT in patients who received adjuvant chemotherapy (AC). In the NAC cohort, PMRT did not change OS, with 7-year OS of 78% with MTX and 79% with PMRT. There was a trend of improved OS with PMRT in patients with residual disease in the breast and lymph nodes (HR 0.70, 95% CI 0.46-1.07). CONCLUSION PMRT improves OS in patients with pT3N0 disease, but the benefit appears limited to those who do not receive AC. PMRT does not improve OS in patients with cT3N0 disease who receive NAC, but there might be a benefit in patients with a poor response to chemotherapy. However, longer follow-up may be needed to make a definitive conclusion about the benefit of PMRT in patients who receive chemotherapy.

中文翻译：

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乳房切除术后放疗与未接受化疗的 T3N0 患者的总生存期改善相关

背景和目的 关于乳房切除术后放疗 (PMRT) 在 T3N0 乳腺癌患者中的效用的回顾性证据有限。我们对国家癌症数据库 (NCDB) 进行了一项回顾性分析，比较了单纯乳房切除术 (MTX) 或 PMRT 治疗的 T3N0 患者的总生存期 (OS)。材料和方法 我们对 2006 年至 2014 年间未接受 NAC 治疗的 NCDB 乳腺癌患者 pT3N0 或接受 NAC 治疗的 cT3N0 患者进行了匹配队列分析。使用逆概率倾向评分对患者的所有可用基线特征进行匹配具有稳定权重的治疗权重 (IPTW)。结果 我们确定了 13,901 名符合条件的患者。在 pT3N0 队列中，MTX 组的中位随访时间为 47 个月，PMRT 组的中位随访时间为 50 个月。在 cT3N0 队列中，MTX 组的中位随访时间为 44 个月，PMRT 组的中位随访时间为 46 个月。与 MTX 相比，接受 PMRT 治疗的 pT3N0 患者的 OS 更高：7 年 OS 分别为 74% 和 65% (P < 0.001)。双重稳健的多变量分析显示 PMRT 与改善的 OS 之间存在关联（HR 0.78，95% CI 0.68-0.89，P < 0.001）。PMRT 对接受辅助化疗 (AC) 的患者没有益处。在 NAC 队列中，PMRT 没有改变 OS，MTX 的 7 年 OS 为 78%，PMRT 为 79%。在乳腺和淋巴结有残留病灶的患者中，PMRT 有改善 OS 的趋势（HR 0.70，95% CI 0.46-1.07）。结论 PMRT 可改善 pT3N0 患者的 OS，但获益似乎仅限于未接受 AC 的患者。PMRT 不能改善接受 NAC 的 cT3N0 患者的 OS，但对化疗反应不佳的患者可能有益。然而，可能需要更长时间的随访才能对接受化疗的患者进行 PMRT 的益处得出明确的结论。