Small cell lung cancer (SCLC) is an aggressive disease, in which more than 80% of patients present distant metastases at the time of first diagnosis. Chemotherapy is considered as the main treatment of extensive disease of SCLC (ED-SCLC), while the role of radiotherapy in the treatment of ED-SCLC is controversial. A case-control study was undertaken of patients diagnosed as ED-SCLC between 2004 and 2010. Fifty-eight patients with overall survival (OS) over 1 year were chosen, and another 58 patients with OS less than 1 year were selected as the control group, with the age, gender, metastasis or no metastasis of the liver, and the response after the first line of chemotherapy matched. The 1-year, 2-year, 3-year, and median OS of the 75 ED-SCLC patients who received radiation were 81.47, 29.89, 22.77%, and 17 months, respectively, and were 61.18, 23.53, 0%, and 16 months, respectively, for patients who did not receive radiation. The χ2 test and odds ratio (OR) estimate demonstrated that these differences were statistically significant (χ2 = 6.38, P = 0.0116; OR = 2.74, 95% confidence interval = 1.24-6.05). These results show that radiotherapy also plays a role in responding patients with extensive stage of SCLC.