我们研究了放疗诱导淋巴细胞减少（RIL）在接受乳腺保乳手术（BCS）治疗的乳腺癌患者中的预后影响。我们纳入了531例接受BCS和辅助放疗的乳腺癌患者。这些患者均未接受（新辅助）化疗。放疗前后进行了绝对淋巴细胞计数（ALC）的检查。主要终点是根据放疗前后ALC比值来评估无复发生存期（RFS）。我们使用二元logistic回归模型来确定RIL的危险因素。不论连续还是分类型（>2.4），放疗前后ALC比值都与RFS相关。在接受整个乳房照射（WBI）和区域淋巴结照射（RNI）的531名患者中，放疗前后ALC比值高的患者RFS明显降低。多变量分析中发现，放疗前后ALC比值低与RFS降低显著相关（HR 2.293，95% CI 1.110-4.735，P = 0.025）。在452名仅接受WBI治疗的患者中，放疗前后ALC比值高仍然与RFS降低显著相关（HR 2.708，95% CI 1.016-7.218，P = 0.046）。二元logistic回归分析中，RNI是临床意义上RIL的唯一显著危险因素。我们的研究结果表明，放疗期间ALC明显下降对预后有负面影响。© 2023年 Springer Nature Limited.

We investigated a prognostic impact of radiotherapy-induced lymphopenia (RIL) in breast cancer patients treated with breast-conservative surgery (BCS). We included 531 breast cancer patients who were treated with BCS and adjuvant radiotherapy. None of these received (neo)adjuvant chemotherapy. Pre- and post- absolute lymphocyte counts (ALC) were reviewed before and after radiotherapy. The primary endpoint was to evaluate recurrence-free survival (RFS) according to the pre-to-post ALC ratio. Binary logistic regression model was used to identify risk factors for RIL. Either continuous or categorical (> 2.4) pre-to-post ALC ratio was associated with RFS. In 531 patients receiving whole breast irradiation (WBI) and regional nodal irradiation (RNI), RFS was significantly reduced in the patients with high pre-to-post ALC ration (> 2.4). In multivariable analysis, low pre-to-post post ALC ratio was significantly related to decreased RFS in the multivariable analysis (HR 2.293, 95% CIs 1.110-4.735, P = 0.025). In 452 patients treated with WBI alone, high pre-to-post ALC ratio was still significantly associated with decreased RFS in the multivariable analysis (HR 2.708, 95% CIs 1.016-7.218, P = 0.046). In binary logistic regression analysis, RNI was only significant risk factor for clinically meaningful RIL. Our findings show that a markedly decrease in ALC during radiotherapy has a negative prognostic impact.© 2023. Springer Nature Limited.