Prophylactic Cranial Irradiation Improved Survival Outcomes Compared to Consolidative Thoracic Radiation Therapy in Extensive-Stage Small Cell Lung Cancer

According to results of a comparison study, prophylactic cranial irradiation (PCI) was associated with greater overall survival (OS) and progression-free survival (PFS) improvement compared to consolidative thoracic radiation therapy (TRT) among patients with extensive-stage small cell lung cancer (SCLC) previously treated with chemotherapy with or without the addition of immunotherapy.

“Extensive-stage [SCLC] continues to have poor survival due to its aggressive behavior, despite improvements with incorporation of immunotherapy with standard chemotherapy,” stated Andrew J. Gross, Seidman Cancer Center, University Hospitals Cleveland Medical Center, Ohio, and coauthors. “Controversy exists regarding the role of TRT and PCI in [extensive-stage]-SCLC due to high recurrence rates.”

In this study, researchers divided 163 patients with extensive-stage SCLC who underwent systemic therapy with or without immunotherapy into cohorts based on systemic therapy use and further divided patients based on use of PCI or TRT. Primary end points included OS and PFS, estimated using the Kaplan-Meier method. The secondary end point was treatment effect with TRT and PCI, estimated using multivariable (MVA) Cox regression. 

At a median follow up of 11 months, 74 patients underwent TRT, and 54 patients underwent PCI. Among patients who underwent PCI, median OS was 15 months compared to 10 months in the TRT group (P = 0.02) and median PFS was 8.5 months, compared to 5 months (P = 0.02). Using MVA Cox regression, statistical significance was maintained. Among patients who underwent TRT, OS improved on univariate analysis (P = 0.002) but MVA Cox regression did not indicate statistical significance. Additionally, TRT did not improve PFS. 

“This study including chemotherapy and chemo-immunotherapy suggests improved outcomes with addition of PCI in patients with ES-SCLC while TRT did not show benefit to either OS or PFS,” concluded Dr Gross and coauthors. However, they noted “a future trial is needed to evaluate the role of TRT and PCI in the era of chemo-immunotherapy.” 

Source: 

Gross AJ, Sheikh S, Kharouta M, et al. The impact of prophylactic cranial irradiation and consolidative thoracic radiation therapy for extensive stage small cell lung cancer in the transition to the chemo-immunotherapy era: A single institution series. Clin Lung Cancer. Published online: August 8, 2023. doi: https://doi.org/10.1016/j.cllc.2023.08.009