Consolidative Thoracic Radiotherapy Improves Survival in ES-SCLC

The most common radiation-associated adverse effect in the investigational group was esophagitis, with 54.4% of patients experiencing grade 1 severity and 15.2% of patients experiencing grade 2 severity.

The addition of consolidative thoracic radiotherapy (cTRT) in patients with extensive stage-small cell lung cancer (ES-SCLC) following progression after first-line chemotherapy improved survival outcomes and decreased intrathoracic progression, according to results from a retrospective study published in BMJ Open.

Of 123 patients with ES-SCLC the median overall survival (OS) was 0.9 years (95% CI, 0.7-1.4) in those who received cTRT vs 0.6 years (95% CI, 0.4-0.9) in those who did not (P = .014). Additionally, the 1- and 2-year OS rates in respective arms were 46.7% (95% CI, 34.3%-63.5%) and 26.3% (95% CI, 15.7%-44.1%) in the cTRT arm vs 23.5% (95% CI, 14.5%-38.0%) and 11.0% (95% CI, 5.0%-24.3%) in the control arm. Furthermore, univariate analysis showed no significant associations of OS sex, smoking status, age, response to chemotherapy, ECOG performance score, or TNM classification at diagnosis, among others. However, cTRT treatment was associated with improved OS (HR, 0.59; 95% CI, 0.39-0.90; P = .015).

The median progression-free survival (PFS) in the cTRT and control arms were 0.4 years (95% CI, 0.4-0.7) and 0.2 years (95% CI, 0.2-0.3), respectively (P = .0001). The 1-year PFS rates in respective arms were 17.5% (95% CI, 9.4%-32.5%) and 3.7% (95% CI, 1.0%-14.3%). In univariate analyses, the only associations with PFS and covariates were for chemotherapy response, with an HR of 1.61 (95% CI, 1.00-2.58; P <.049), and cTRT treatment, with an HR of 0.48 (95% CI, 0.32-0.72; P <.001). Additionally, multivariate analysis revealed that cTRT improved OS (HR, 0.53; 95% CI, 0.31-0.90; P = .019) and PFS (HR, 0.46; 95% CI, 0.31-0.69; P <.001).

“In this real-world study, we report the outcomes of patients with ES-SCLC who were potential candidates for cTRT treated at our tertiary cancer center. Our study cohort comprised patients diagnosed with ES-SCLC, treated at a single tertiary cancer center, predominantly representing patients from urban and suburban communities,” lead author Vijithan Sugumar, a medical student in the Department of Medicine of the University of Toronto, wrote in the publication with study coinvestigators. “We report real-world data from 2013 to 2022, demonstrating the addition of cTRT in patients with ES-SCLC without progressive disease after first-line chemotherapy is associated with improved OS and PFS, and decreased intrathoracic progression with tolerable [adverse] effects. A future study of how to optimally integrate and define the benefit of cTRT with first-line chemoimmunotherapy is warranted.”

The retrospective cohort study included patients 18 years and older with biopsy-proven ES-SCLC who received at least 4 lines of chemotherapy and had complete medical records. Only patients who attained complete response (CR), partial response (PR), or stable disease (SD) per RECIST v. 1.1. Patients treated with immunotherapy were excluded from the study.

The efficacy end points of the study were OS, PFS, and recurrence rates in the cTRT and control groups. Treatment tolerability was assessed for those who received cTRT.

A total of 76.4% of patients experienced a PR with radiation therapy, with 18.7% experiencing SD, and 4.8% attaining a CR. Platinum-based chemotherapy was administered in 94.3% of patients, with use of platinum-based chemotherapy and response to first-line chemotherapy balanced between the cTRT and control groups.

The most common radiation-associated adverse effect in the investigational group was esophagitis, with 54.4% of patients experiencing grade 1 severity and 15.2% of patients experiencing grade 2 severity. Only 1 patient experienced grade 1 pneumonitis following cTRT dosing.

Reference

Sugumar V, Salunkhe R, Lone H, et al. Retrospective cohort study assessing clinical outcomes of patients with extensive-stage small cell lung cancer treated with and without consolidative thoracic radiotherapy at the Princess Margaret Cancer Centre. BMJ Open. 2024;15(3):e093943. doi:10.1136/bmjopen-2024-093943