Consolidative Radiotherapy for Extensive-Stage Small Cell Lung Cancer: Outcomes Based on Completeness of...

To assess the impact of complete versus incomplete consolidative radiotherapy and of oligometastatic versus polymetastatic status on overall survival (OS) and progression-free survival (PFS) in extensive-stage small cell lung cancer (ES-SCLC) patients following first-line systemic therapy.

In this retrospective cohort study of 70 ES-SCLC patients treated between February 2013 and June 2020, patients were categorized by consolidative RT completeness, defined as radiotherapy to all radiographically targetable residual disease (complete consolidative radiotherapy [CCRT], n = 28; incomplete consolidative radiotherapy [ICRT], n = 42), and metastatic state (oligometastatic ≤ 3 organs and ≤ 3 lesions/organ, n = 36; polymetastatic, n = 34). OS and PFS were analyzed with Kaplan-Meier and log-rank tests. Restricted mean survival time (RMST) differences and ratios with consolidation completeness as the primary predictor were adjusted for age, sex, Eastern Cooperative Oncology Group status, organ involvement (brain, liver, pleural/pericardial), metastatic state, and immunotherapy receipt. A secondary analysis assessed RMST by metastatic state with identical covariates.

With a median follow-up of 38.2 months, CCRT was associated with adjusted RMST gains of 6.47 months for OS (95% CI, 1.08-11.85; P = .0185) and 4.63 months for PFS (95% CI, 1.12-8.14; P = .0097) versus ICRT through 36 months. Among oligometastatic patients, CCRT was associated with OS gains of 7.90 months through 36 months (95% CI, 1.75-14.05; P = .0118) and PFS gains of 2.46 months through 12 months (95% CI, 0.24-4.67; P = .0298). Oligometastatic status was not independently predictive.

CCRT was associated with improved OS and PFS compared with ICRT in ES-SCLC, whereas oligometastatic status alone was not independently associated with these outcomes. These findings warrant prospective validation.