Can consolidative thoracic radiotherapy improve outcomes in extensive-disease small cell lung cancer after chemotherapy with complete/near-complete responders?

Abstract

Background: In extensive-disease-small cell lung cancer (ED-SCLC), the median survival is 8-10 months and 2-year survival is <5%. Primary tumor progression occurs in 90% of patients approximately within 1 year. The role of consolidative thoracic radiotherapy (C-TRT) for the postchemotherapy residue with the aim of improving local control (LC) and survival is currently of great interest. The objective of this study is to determine the effectiveness of C-TRT on LC, progression-free survival (PFS), and overall survival (OS) in ED-SCLC. Materials and Methods: Medical records of patients diagnosed as SCLC between January 2010 and December 2015 were evaluated retrospectively. Patients who received C-TRT were identified. Pre- and post-chemotherapy radiological evaluations, radiotherapy schedules, relapse patterns, toxicity incidence, LC, PFS, and OS were analyzed. Results: Among 552 SCLC patients, 26 ED-SCLC patients who underwent C-TRT were analyzed. Median follow-up was 7.5 months (range, 6.5-8.5 months). Nearly 50% of the patients had >4 metastatic lesions. Restaging was performed mostly by positron emission tomography/computed tomography and cranial magnetic resonance imaging. All patients had complete or near-complete response distantly. C-TRT was 10 × 300 cGy (n = 1), 23 × 200 cGy (n = 2), 25 × 200 cGy (n = 7), 30 × 200 cGy (n = 12), and 33 × 200 cGy (n = 4). There was no toxicity ≥ Grade 3. LC rate was 77%; there was no isolated local relapse. PFS was 3 months. Median survival was 13 months. The 1- and 2-year OS rates were 62% and 8%, respectively. Conclusion: In ED-SCLC patients, C-TRT may prevent isolated local recurrence and may improve 1-year survival. This survival improvement might be the reflection of high intrathoracic control achieved in 77% of patients.