Adjuvant chemotherapy versus chemoradiotherapy for small cell lung cancer with lymph node metastasis: a retrospective observational study with use of a national database in Japan

BACKGROUND: The optimal postoperative treatment strategy for small cell lung cancer (SCLC) remains unclear, especially in patients with lymph node metastasis. We aimed to compare the outcomes of patients with SCLC and lymph node metastasis treated with postoperative adjuvant chemotherapy or chemoradiotherapy. METHODS: We retrospectively collected data on patients with postoperative SCLC diagnosed with N1 and N2 lymph node metastasis from the Diagnosis Procedure Combination database in Japan, between July 2010 and March 2015. We extracted data on patient age, sex, comorbidities, and TNM classification at lung surgery; operative procedures, chemotherapy drugs, and radiotherapy during hospitalization; and discharge status. Recurrence-free survival was compared between the chemotherapy and chemoradiotherapy groups using multivariable Cox regression analysis. RESULTS: Median recurrence-free survival was 1146 days (95% confidence interval [CI], 885–1407) in the chemotherapy group (n = 489) and 873 days (95% CI, 464–1282) in the chemoradiotherapy group (n = 75). There was no significant difference between these after adjusting for patient backgrounds (hazard ratio, 1.29; 95% CI, 0.91–1.84). CONCLUSIONS: There was no significant difference in recurrence-free survival between patients with SCLC and N1-2 lymph node metastasis treated with postoperative adjuvant chemotherapy and chemoradiotherapy. Further randomized clinical trials are needed to address this issue.