Table 1_Temporal dynamics of lymphocytes in prostate cancer patients treated with proton therapy.docx

Radiotherapy can be both immunosuppressive and immunostimulatory. Radiation-induced lymphopenia (RIL) is an ongoing challenge in cancer treatment. We investigated weekly changes in the absolute lymphocyte count (ALC) during proton radiotherapy, evaluating the effects of different dosage, fractionation schedules, and pelvic node irradiation (PNI). Prostate cancer patients were prospectively chosen for this study, due to their relatively homogenous treatment plans. Treatment protocols were categorized into three groups: Group A (n=52) received 36.25 Gy/5-fractions, Group B (n=60) underwent 63 Gy/21-fractions and group C (n=69) received 63 Gy/21-fractions plus PNI. To account for individual characteristic differences, a new categorization method was made, according to the change in ALC relative to the baseline. Lymphopenia (ALC < 1000 K/μL) developed in 8%, 17% and 84% of patients in groups A, B, and C, respectively. An initial increase in ALC occurred in 44%, 47% and 28% of groups A, B and C, respectively, and declined with proceeding fractions. Patients with PNI had the most pronounced reduction in their ALC relative to the baseline. Increased dosage and fractionation led to a higher incidence of lymphopenia. Understanding which factors influence ALC in particle therapy is vital for leveraging the immune-enhancing effects of radiotherapy, while minimising its immunosuppressive impacts.

放射治疗（Radiotherapy）兼具免疫抑制与免疫刺激双重效应。辐射诱导性淋巴细胞减少症（Radiation-induced lymphopenia, RIL）是癌症治疗中亟待解决的长期难题。本研究针对质子放射治疗（Proton Radiotherapy）期间绝对淋巴细胞计数（Absolute Lymphocyte Count, ALC）的周度变化展开系统探究，评估了不同照射剂量、分割方案以及盆腔淋巴结照射（Pelvic Node Irradiation, PNI）对该指标的影响。
本研究前瞻性入组前列腺癌患者，因其临床治疗方案相对均一。将受试者的治疗方案划分为三组：A组（n=52）接受36.25 Gy/5次分割照射，B组（n=60）采用63 Gy/21次分割照射方案，C组（n=69）则在63 Gy/21次分割照射的基础上联合盆腔淋巴结照射。
为消除个体特征差异带来的干扰，本研究基于绝对淋巴细胞计数相对基线水平的变化建立了全新的分类方法。结果显示，A、B、C三组患者中，分别有8%、17%及84%出现淋巴细胞减少症（ALC < 1000 K/μL）；A、B、C组分别有44%、47%及28%的患者初始ALC水平升高，且随着放疗分割次数的增加逐渐下降。其中，接受盆腔淋巴结照射的患者，其ALC相对基线的降幅最为显著。
研究表明，更高的照射剂量与分割次数会提升淋巴细胞减少症的发生率。明确粒子治疗（Particle Therapy）中影响绝对淋巴细胞计数的相关因素，对于在利用放射治疗免疫增强效应的同时，最大限度降低其免疫抑制作用具有重要意义。