Influence of the timing of tumor regression after the initiation of chemoradiotherapy on prognosis in patients with limited-disease small-cell lung cancer achieving objective response

Purpose: Chemoradiotherapy (CHRT) yields a favorable antitumor activity in patients with limited-stage small-cell lung cancer (LD-SCLC) with a response rate of around 80%. Even in such responders, the majority recur, indicating the importance of identifying a subset of patients with a poor outcome earlier through the treatment. We investigated whether the timing of obtaining tumor regression with the CHRT could affect the prognosis in LD-SCLC patients who finally achieved the objective response through the treatment. Patients and methods: We retrospectively reviewed medical charts of 70 LD-SCLC patients who obtained complete response (CR) or partial response (PR) with the 3 or 4 cycles of first-line CHRT between 1988 and 2006. Results: In the whole 70 patients with CR/PR, the median survival time and median progression free survival (PFS) were 39.6 and 12.3. months, respectively. Fifty-two (74.3%) of the 70 patients entered CR/PR after the first cycle of CHRT, and their 2-year survival rates were significantly longer than that in the remaining 18 patients without entering CR/PR yet at the end of first cycle (72.3% and 7.1%, respectively, p< 0.001). Cox regression analysis showed that the early response to the treatment was a significant prognostic factors (hazard ratio = 0.098; 95% confidence interval = 0.036-0.269). Regarding PFS, similar findings were observed. Conclusions: Patients without entering CR/PR yet after the first course had a poorer outcome even though the objective response was finally confirmed through the treatment. Development of more effective treatments for these high-risk patients is warranted to improve their poor prognosis.