WCLC 2025 - Posters & ePosters-EP.08.19 Timing and Predictors of Lymphopenia in Lung Cancer Patients Undergoing Proton and Photon Chemoradiotherapy

EP.08.19 Timing and Predictors of Lymphopenia in Lung Cancer Patients Undergoing Proton and Photon Chemoradiotherapy

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This retrospective study evaluated the timing and predictors of grade 3 lymphopenia (G3L) in 68 lung cancer patients treated definitively with proton (PT-CRT, n=47) or photon chemoradiotherapy (PH-CRT, n=21) at a single institution. Treatment-induced lymphopenia is a significant adverse effect, especially relevant due to the growing use of immune checkpoint inhibitors in lung cancer therapy.<br /><br />Patients received conventionally fractionated radiotherapy (median 60 Gy/GyE in 30 fractions) alongside chemotherapy, mostly paclitaxel/carboplatin. The groups were comparable in age, gender, chemotherapy regimen, and target volumes, though median lung dose (MLD) was lower in PT-CRT (10.7 Gy vs. 15 Gy). The median time to develop G3L was longer with PT-CRT (31 days) compared to PH-CRT (21 days), a trend that approached but did not reach statistical significance (p=0.07).<br /><br />Univariate Cox regression identified larger planning target volume/clinical target volume (PTV/CTV) (p=0.015) and treatment modality (p=0.08) as factors correlated with G3L onset. However, multivariate analysis showed only PTV/CTV remained a significant predictor (p=0.015). The radiation modality’s effect diminished after accounting for these factors, likely due to confounding variables such as treatment volume and limited sample size.<br /><br />The study concludes that G3L is common across both proton and photon chemoradiotherapy and strongly associated with larger radiation target volumes. While PT-CRT may delay lymphopenia onset, treatment volume is a more robust predictive factor. Given the increasing integration of immunotherapy, future research should focus on optimizing radiation planning and target volume management to minimize lymphopenia and improve clinical outcomes in lung cancer patients undergoing chemoradiotherapy.

Asset Subtitle

Robert Press

Meta Tag

Speaker Robert Press

Topic Local-Regional Non-small Cell Lung Cancer

Keywords

grade 3 lymphopenia

lung cancer

proton chemoradiotherapy

photon chemoradiotherapy

planning target volume

clinical target volume

immune checkpoint inhibitors

chemoradiotherapy toxicity

median lung dose

treatment volume