Impact of time-to-treatment initiation on survival in single primary non-small cell lung Cancer: A population-based study

Background: Understanding the effects of a delayed time-to-treatment initiation(TTI) for non-small cell lung cancer (NSCLC) is vital.Methods: We analyzed NSCLC data from the Surveillance, Epidemiology, and End Results database, focusing on lung adenocarcinoma (LUAD) and lung squamous carcinoma (LUSC). TTI was studied as both continuous and dichotomous variables. Restricted cubic splines were employed to identify potential nonlinear dependency between the hazard ratio (HR) and TTI. Propensity score matching was used to ensure a balanced patient allocation, and then survival differences between groups were assessed using Kaplan-Meier analysis and competing risk models. We used overall survival (OS) as the primary outcome and cancer-specific cumulative mortality (CSCM) as a complementary indicator. Finally, sensitivity analyses were performed on censored data.Results: A total of 80,020 with NSCLC were analyzed. TTI was assessed as a continuous variable, showing a noticeable increase in the HR for stage I to II NSCLC with TTI >1 month. Conversely, the trend for stage III to IV NSCLC was the opposite. In stage I LUAD, the 'early' group demonstrated a higher OS compared to the 'delayed' group (Log-rank P = 0.002), while there was no significant difference in CSCM (Fine-gray P = 0.321). In stage I LUSC, there was no significant difference in OS(Log-rank P = 0.260), but the 'early' group had a lower CSCM (Fine-gray P = 0.018). For stage II-IV NSCLC, the 'delayed' group did not exhibit a negative impact on OS or CSCM. The sensitivity analysis further supported the results of the main analysis.Conclusion: Prolongation of TTI >= 31 days has a negative impact on OS or CSCM in stage I NSCLC only. Further exploration and validation are needed to determine whether these results can be used as evidence for a 'safe' TTI threshold setting for future NSCLC.