Consolidative Thoracic Radiotherapy Displays Safety, Efficacy in ES-SCLC

The median overall survival favored cTRT, at 28.68 months vs 16.30 months with non-cTRT treatments, and the respective 12- and 18-month OS rates were 82.8% vs 64.3% and 69.0% vs 39.0%.

Consolidative thoracic radiotherapy (cTRT) following first-line chemoimmunotherapy displayed prolonged survival and an acceptable safety profile in patients with extensive-stage small cell lung cancer (ES-SCLC) compared to non-cTRT treatment, according to findings from a retrospective analysis published in Annals of Medicine.1

After a median follow-up of 34.66 months, the median progression-free survival (PFS) with cTRT was 11.50 months (95% CI, 5.63-17.37) vs 8.02 (95% CI, 5.27-10.76) months with non-cTRT treatments (HR, 0.60; 95% CI, 0.36-0.99). Additionally, the 6- and 12-month PFS rates in each respective arm were 79.0% vs 71.4% and 46.7% vs 26.2%.

Additionally, the median overall survival (OS) favored cTRT, at 28.68 months (95% CI, 20.32-37.04) vs 16.30 months (95% CI, 12.81-19.78) with non-cTRT treatments (HR, 0.56; 95% CI, 0.32-0.96). Furthermore, the respective 12- and 18-month OS rates were 82.8% vs 64.3% and 69.0% vs 39.0%.

A univariate analysis revealed that extrathoracic metastases (HR, 1.92; 95% CI, 1.05-3.57; P = .04), cycles of immunotherapy (HR, 1.88; 95% CI, 1.09-3.24; P = .02), and receipt of cTRT (HR, 0.56; 95% CI, 032-0.96; P = .03) were significantly prognostic of OS. Additionally, a multivariate analysis revealed that cycles of immunotherapy (P = .03) and receipt of cTRT (P = .046) were positively associated with OS, with extrathoracic metastases not having a significant effect.

Furthermore, an exploratory subgroup analysis showed particular benefit among those younger than 65, those with an ECOG performance status of 0 to 1, those with no extrathoracic metastases, those with fewer than 3 initial distant metastases, those who received less than 6 cycles of immunotherapy, and those who did not receive prophylactic cranial irradiation.

“This study thoroughly compared cTRT with non-cTRT on survival, toxicity, and confirmed the feasibility of combining cTRT with immunotherapy for ES-SCLC,” study author Nan Yao, of the Department of Radiation Oncology in the Affiliated Wuxi People’s Hospital of Nanjing Medical University in Wuxi, Jiangsu, China, wrote in the publication with study coinvestigators. “First-line chemoimmunotherapy combined with cTRT is safe and significantly improves survival in [patients with] ES-SCLC. Further studies of this regimen are warranted.”

Patients included in the analysis were treated between March 2019 and November 2021 for ES-SCLC with first-line chemoimmunotherapy followed by immunotherapy maintenance with or without cTRT. Patients were 18 years or older, had histologically or cytologically confirmed SCLC, and maintained a good response following first-line chemoimmunotherapy.

Patients across the study were treated with immunotherapy plus platinum-etoposide chemotherapy every 3 weeks for a maximum of 6 cycles. Additionally, maintenance immunotherapy was given every 3 weeks until disease progression or unacceptable toxicity, and cTRT was initiated at the discretion of the treating physician with intensity modulated radiation therapy.

In the cTRT (n = 29) and non-cTRT (n = 43) groups, the median age was 63 years (range, 34-80) vs 65 years (range, 49-82). Most patients were male (68.97% vs 79.07%) and had a smoking history (62.07% vs 55.81%). Furthermore, 93.10% vs 83.72% of patients had an ECOG performance status of 0 to 1, 65.52% vs 62.79% had extrathoracic metastases, and 75.86% vs 69.77% had fewer than 3 initial distant metastases. Additionally, most patients in either arm were partial responders to initial treatment (89.66% vs 93.02%) and did not undergo prophylactic cranial irradiation (62.07% vs 81.40%); however, 55.17% of patients in the cTRT arm received 6 or more immunotherapy cycles vs 48.84% of the non-cTRT arm.

The primary end points of the study included PFS, OS, and safety. Toxicities were graded according to Common Terminology Criteria for Adverse Events (CTCAE) v5.0.

The most common any-grade treatment-related adverse effects in the cTRT and non-cTRT arms included decreased white blood cell count (72.41% vs 69.77%), decreased neutrophil count (51.72% vs 34.88%), anemia (27.59% vs 25.58%), abnormal liver function (24.14% vs 20.93%), and decreased platelet count (20.69% vs 20.93%). The most common grade 3 or higher TRAEs included decreased neutrophil count (24.14% vs 20.93%), decreased white blood cell count (10.34% vs 13.94%), decreased platelet count (6.90% vs 9.30%), and abnormal liver function (6.90% vs 6.98%).

Reference

Yao N, Li S, Hu L, et al. Consolidative thoracic radiotherapy improves the prognosis of extensive stage small-cell lung cancer patients in the chemoimmunotherapy era: a multicenter retrospective analysis. Ann Med. 57;1:2542434. doi:10.1080/07853890.2025.2542434