Intrathoracic extensive-stage small cell lung cancer: assessment of the benefit of thoracic and brain radiotherapy using the SEER database.

BACKGROUND: Extensive-stage small cell lung cancer (ESCLC) includes metastatic disease and locally advanced disease confined to the thorax that cannot be encompassed in a typical radiation portal. We assessed and then compared the benefits of thoracic radiotherapy (TRT) and/or brain radiotherapy (BRT) on overall survival (OS) between the intrathoracic (T-ESCLC) and metastatic (M-ESCLC) groups using the Surveillance Epidemiology and End Results database.

METHODS: TRT and BRT data were available for 10150 patients treated from 1988-1997. The T-ESCLC group included 1774 patients. The Kaplan-Meier method was used to estimate OS and the proportional hazards model was used to estimate OS hazard ratios for prognostic factors including age, gender, race, tumor size, T/N stage, TRT, and BRT.

RESULTS: The 2-year OS for T-ESCLC was 7.8 % compared to 3 % in the M-ESCLC group (p < 0.001). In the T-ESCLC group, TRT and BRT were delivered to 750 and 102 patients, respectively. The 2-year OS was 13 % in the TRT group compared to 4.1 % in the no-TRT group (p ≤ 0.001) and 22.5 % in the BRT group compared to 7 % in the no-BRT group (p < 0.001). In the M-ESCLC group, TRT and BRT were delivered to 3093 and 1887 patients, respectively. The 2-year OS was 4.4 % in the TRT group compared to 2.8 % in the no-TRT group (p < 0.001) and 4.3 % in the BRT compared to 2.6 % in the no-BRT group (p < 0.001). Age, gender, TRT and BRT were significant OS prognostic factors in both groups.

CONCLUSIONS: Our study suggests that T-ESCLC is a disease entity distinct from M-ESCLC. Prospective studies to determine whether TRT should be recommended for the thoracic-only subgroup are warranted.