Re-irradiation in central lung cancer-a monocentric detailed analysis

Lung cancer still continues to be associated with a high rate of locoregional recurrence, which remains a therapeutic challenge. Re-irradiation can be a viable treatment option; however, due to the proximity to critical organs, it requires special caution, particularly in cases of centrally located recurrences. The aim of this analysis was to evaluate our monocentric experience of re-irradiation of central lung cancer recurrences with individual dose prescription in terms of treatment outcomes and to conduct a detailed dosimetric analysis.

In this single-centre study, 30 patients who received type 2 re-irradiation between 2014 and 2024 for a centrally located lung cancer recurrence were analyzed. Overall survival (OS), progression-free survival (PFS) and local control (LC) were calculated using the Kaplan-Meier method. Prognostic factors were evaluated using univariate log-rank tests and multivariate Cox regression. The values for the dosimetric analysis were determined by registering the radiation therapy planning CT scans from the first and second courses of radiotherapy.

The cohort consisted of n = 24 (80%) patients with non-small cell lung cancer (NSCLC) and n = 6 (20%) small cell lung cancer (SCLC). At the time of locoregional recurrence diagnosis, 40% presented with metastatic disease. The median follow-up time was 10 months (range: 0-69). The median interval between the first and second course of radiation therapy was 12 months (range: 2-97). The median total equivalent dose in 2 Gy fractions (EQD2) of re-irradiation was 49.5 Gy (α/β = 10). The 1‑year OS, 1‑year PFS and 1-year LC rates were 61%, 19.3% and 80.1%, respectively. Disease progression occurred predominantly in the form of distant metastases (n = 13, 59.1%), followed by local (n = 4, 18.2%) and locoregional relapse (n = 3, 13.6%). In the multivariate analysis, only patient age over 65 years was identified as an independent predictor of improved PFS, while no independent prognostic factors were found for overall survival or local control. It is noteworthy that re-irradiation was well tolerated; there was a single case of grade 3 late toxicity in the form of esophageal stenosis and one case of grade 2 radiation induced pneumonitis. All patients whose cumulative V60 dose to the esophagus exceeded 50% developed clinically relevant acute grade 2 esophagitis (n = 5, 16.7%).

Overall, our results support the growing evidence that thoracic re-irradiation for centrally located lung cancer can achieve favorable local control with acceptable and manageable toxicity.