BACKGROUND We investigated the effect of downstaging on OS in LD-SCLC patients treated with first-line treatment.

PATIENTS AND METHODS We retrospectively reviewed 210 LD-SCLC patients who were treated with first-line treatment at Seoul National University Hospital between April 1999 and November 2012. Compared with initial tumor, node, metastases (TNM) stage, cases that showed a lower TNM stage after treatment were defined as 'downstaging.' The relationship between downstaging and OS was analyzed, and a subgroup analysis on the responders was performed.

RESULTS After first-line treatment, 78 (37.1%) patients achieved complete response, 97 (46.2%) achieved PR, and 35 (16.7%) experienced stable disease or progressive disease. A hundred and fifty one patients (71.9%) showed downstaging of their diseases, and the remaining 59 patients (28.1%) showed no change or upstaging. The median OS for patients achieving downstaging and no change/upstaging were 32.8 months and 13.1 months, respectively (P < .001). Of the 97 patients who achieved PR, the OS was significantly longer in patients who showed downstaging than those who did not (25.8 months vs. 13.8 months, respectively; P = .004). In multivariate analyses, female sex, downstaging, lower initial TNM stage, and prophylactic cranial irradiation were independent good prognostic factors for OS.

CONCLUSION Downstaging might be an independent good prognostic factor in LD-SCLC. Specifically, downstaging is expected to be useful for stratification of patients achieving PR. Further prospective studies are warranted to verify whether patients who achieved PR without downstaging can be candidates for consolidation treatments after first-line treatment.