Department of Radiation Oncology, Shanghai Proton and Heavy Ion Center, Fudan University Cancer Hospital, Shanghai, China; Shanghai Key Laboratory of Radiation Oncology, Shanghai, China; Shanghai Engineering Research Center of Proton and Heavy Ion Radiation Therapy, Shanghai, China; Department of Radiation Oncology, Fudan University Shanghai Cancer Center, Shanghai, China; Department of Oncology, Shanghai Medical College, Fudan University, Shanghai, China; Shanghai Clinical Research Center for Radiation Oncology, Shanghai, China.
Shanghai Key Laboratory of Radiation Oncology, Shanghai, China; Department of Radiation Oncology, Fudan University Shanghai Cancer Center, Shanghai, China; Department of Oncology, Shanghai Medical College, Fudan University, Shanghai, China; Shanghai Clinical Research Center for Radiation Oncology, Shanghai, China.
Int J Radiat Oncol Biol Phys. 2023 Jul 1;116(3):579-589. doi: 10.1016/j.ijrobp.2022.12.030. Epub 2022 Dec 28.
Lymphopenia is a common adverse effect of radiation therapy (RT). Little is known about the difference in lymphopenia between intensity modulated (photon) radiation therapy (IMRT) and proton and carbon ion radiation therapy (PCIRT). This study aimed to investigate lymphopenia differences between IMRT and PCIRT in non-small cell lung cancer (NSCLC).
Clinical and dosimetric parameters were collected from 343 patients who received definitive IMRT or PCIRT for NSCLC. Severe lymphopenia (SRL) was defined as an absolute lymphocyte count (ALC) ≤0.5 × 10 cells/μL. Overall survival (OS) was analyzed using the Kaplan-Meier method. Propensity score matching was performed between the IMRT and PCIRT groups. Least absolute shrinkage and selection operator analysis was used to select appropriate dosimetric parameters. Univariate and multivariate logistic regression analyses were conducted to identify the predictors of SRL.
Compared with the IMRT group, the PCIRT group was less likely to develop SRL (P < .001). Compared with the non-SRL group, the SRL group showed significant association with poorer OS, with a median survival time of 29.2 versus 15.0 months (P = .046). IMRT was an independent risk factor of SRL (P = .004). A lower ALC before RT (P = .030) and larger planning target volume (PTV) (P = .002) were also significant independent risk factors for SRL. Moreover, the majority of dosimetric parameters of organs at risk in PCIRT were lower than those in IMRT (P < .001). Thoracic vertebra V5 (P = .002) and aorta V5 (P = .026) were identified as independent risk predictors of SRL after adding dosimetric parameters to the regression model.
Compared with IMRT, PCIRT could reduce SRL incidence, possibly by limiting thoracic vertebra and aortic doses, and SRL was associated with poor outcomes in patients with NSCLC.
淋巴细胞减少是放射治疗（RT）的常见不良反应。对于调强光子放疗（IMRT）和质子及碳离子放疗（PCIRT）之间的淋巴细胞减少差异知之甚少。本研究旨在探讨非小细胞肺癌（NSCLC）中 IMRT 和 PCIRT 之间的淋巴细胞减少差异。
从 343 例接受 NSCLC 根治性 IMRT 或 PCIRT 的患者中收集临床和剂量学参数。严重淋巴细胞减少症（SRL）定义为绝对淋巴细胞计数（ALC）≤0.5×10 个细胞/μL。采用 Kaplan-Meier 法分析总生存期（OS）。对 IMRT 和 PCIRT 组进行倾向评分匹配。使用最小绝对收缩和选择算子分析选择合适的剂量学参数。采用单因素和多因素逻辑回归分析确定 SRL 的预测因素。
与 IMRT 组相比，PCIRT 组发生 SRL 的可能性较小（P＜0.001）。与非 SRL 组相比，SRL 组的 OS 显著较差，中位生存时间为 29.2 个月与 15.0 个月（P=0.046）。IMRT 是 SRL 的独立危险因素（P=0.004）。放疗前较低的 ALC（P=0.030）和较大的计划靶区（PTV）（P=0.002）也是 SRL 的独立危险因素。此外，PCIRT 中危及器官的大多数剂量学参数均低于 IMRT（P＜0.001）。在回归模型中加入剂量学参数后，胸椎体 V5（P=0.002）和主动脉 V5（P=0.026）被确定为 SRL 的独立危险因素。
与 IMRT 相比，PCIRT 可降低 SRL 的发生率，可能是通过限制胸椎体和主动脉剂量，SRL 与 NSCLC 患者的不良预后相关。
