Timing of treatment in small-cell lung cancer.

Small-cell lung cancer (SCLC) is an aggressive disease with poor survival and rapid doubling time. Current practice is to treat SCLC as soon as possible but evidence on appropriate timing of treatment from diagnosis (TTD) is lacking. This is a retrospective analysis of SCLC patients from the 2012 to 2015 Kentucky Cancer Registry. Data collected included age at diagnosis, stage, gender, race, insurance and treatment. Factors and survival associated with TTD were identified with logistic regression analyses and Cox proportional hazards models. Among the 2992 SCLC patients, 2371 (79%) of SCLC patients were treated with one or more treatment modalities. Among treated patients, 93% received chemotherapy ± radiation with the mean TTD of 18 days. Most patients (80%) have TTD of ≤ 4 weeks with 33% treated within 1 week, 20% 1-2 weeks, and 27% 2-4 weeks from diagnosis. Delay in treatment (TTD > 4 weeks) was less in stage III and IV disease (odds ratio: 0.33 and 0.27 respectively, p < 0.01) but not significantly associated with age, race, gender, and insurance. One and two-year survival of patients with TTD ≤ 4 weeks was significantly worse when compared to > 4 weeks (hazard ratio = 1.43, 95% CI 1.2-1.6, p < 0.01; HR = 1.45, 95% CI 1.3-1.6, p < 0.01 respectively). These results show a trend toward better survival with late treatment of SCLC. Therefore, a general urgency to treat SCLC needs to be re-evaluated with consideration of patients needing more optimization before treatment. Further studies are needed to better clarify the appropriate timing of treatment from diagnosis in SCLC and who will benefit from early versus late treatment.