Optimal dose-volume histogram thresholds for radiation pneumonitis prevention in lung cancer patients receiving immunotherapy.

OBJECTIVES

To evaluate the incidence of symptomatic radiation pneumonitis (RP) in lung cancer patients receiving immunotherapy and radiotherapy.

MATERIALS AND METHODS

We retrospectively analyzed 389 lung cancer patients who underwent thoracic radiotherapy with/without immunotherapy at the Third Xiangya Hospital (January 2015-September 2024). Propensity score matching (PSM) was employed to compare RP incidence. Univariate, multivariate, and stepwise regression analyses were conducted to identify predictors of grade ≥ 2 RP.

RESULTS

Symptomatic RP occurred in 30.33% (118/389) and 7.46% (29/389) of patients for grades ≥ 2 and ≥ 3, respectively. Patients receiving concurrent immunotherapy-radiotherapy demonstrated a significantly lower incidence of grade ≥ 2 RP compared to other treatment groups (p < 0.05). Multivariable analysis revealed no significant association between immunotherapy administration and RP risk. Lung V20 (≤ 20% vs. > 20%) emerged as a critical predictor: grade ≥ 2 RP incidence was 4.05-8.73% with V20 ≤ 20%, versus 53.8-65.5% when V20 exceeded 20%.

CONCLUSIONS

Immunotherapy did not raise the risk of grade ≥ 2 RP. Maintaining lung V20 ≤ 20% may serve as an optimal dosimetric threshold for RP prevention in patients undergoing combined-modality therapy.

CLINICAL TRIAL NUMBER

Not applicable.