Rates of Overall Survival and Intracranial Control in the Magnetic Resonance Imaging Era for Patients With Limited-Stage Small Cell Lung Cancer With and Without Prophylactic Cranial Irradiation

Abstract

Importance: Historical data suggest that there is an overall survival benefit associated with prophylactic cranial irradiation (PCI) in patients with small cell lung cancer (SCLC). However, as the fidelity of magnetic resonance imaging (MRI) of the brain continues to improve, this idea is now being questioned, with recent research showing no survival benefit associated with PCI in extensive-stage SCLC; however, the role for PCI is not clear in patients with limited-stage SCLC (LS-SCLC).

Objective: To report the overall survival and rates of intracranial control for patients with LS-SCLC, all staged with MRI, who either did or did not undergo PCI.

Design, setting, and participants: This cohort study included 297 patients with LS-SCLC at a large US academic cancer center. Patients were treated with thoracic radiation; 205 also underwent PCI and 92 did not. All patients underwent at least baseline MRI, with restaging brain MRI and/or computed tomography; they did not have disease progression after thoracic radiation treatment. A propensity score-matching analysis was undertaken in an attempt to adjust for potential bias. Of the 297 patients who met the inclusion criteria, the propensity score was calculated for 295 patients, using patient, tumor, and treatment characteristics. Data were analyzed in October 2019.

Intervention: Prophylactic cranial irradiation in patients with LS-SCLC.

Main outcomes and measures: The rate of overall survival and intracranial control.

Results: Of the 297 patients, 162 (54.5%) were men. The median age was 62.2 years (range, 27.0-85.0 years) for patients who underwent PCI and 68.6 years (range, 40.0-86.0 years) for those who did not undergo PCI. The 3-year cumulative incidence rate of brain metastases was higher in the no-PCI group vs the PCI group, when counting death as a competing risk, but the difference was not statistically significant (20.40% [95% CI, 12.45%-29.67%] vs 11.20% [95% CI, 5.40%-19.20%]; P = .10). The use of PCI was not associated with a difference in overall survival between the patient groups (hazard ratio, 0.844; 95% CI, 0.604-1.180; P = .32).

Conclusions and relevance: These findings suggest that patients with LS-SCLC staged with MRI who undergo PCI after thoracic radiation treatment were not associated with a decreased risk of developing new brain metastases compared with patients who do not undergo PCI. The use of PCI was not associated with an overall survival benefit for such patients.

Conflict of interest statement

Conflict of Interest Disclosures: Dr Fang reported receiving grants from the American Society of Clinical Oncology outside the submitted work. Dr Lin reported receiving grants from Genentech and Hitachi Chemical Diagnostics, grants and personal fees from BeyondSpring Pharmaceuticals, and personal fees from Elekta, AstraZeneca, and Varian Medical Systems outside the submitted work. No other disclosures were reported.

Figures

Figure 1.. Cumulative Incidence Rate of Distant Brain Metastasis, With Death as Competing Risk, Among Patients With Limited-Stage Small Cell Lung Cancer

Unadjusted analysis was performed on a propensity-matched sample of patients who did or did not undergo prophylactic cranial irradiation (PCI).

Figure 2.. Comparison of Overall Survival in Propensity-Matched Patients With Limited-Stage Small Cell Lung Cancer Who Did and Did Not Undergo Prophylactic Cranial Irradiation (PCI)

HR indicates hazard ratio.