Treatment Timeliness and Impact on Survival in Extensive Stage Small Cell Lung Cancer.

Abstract

Introduction: Rapid diagnosis and treatment initiation are widely viewed as key principles in the management of extensive-stage small cell lung cancer (ES-SCLC). The Australian Optimal Care Pathway (OCP) for lung cancer recommends confirmation of diagnosis within 2 weeks of initial specialist review and initiation of treatment within 6 weeks of specialist referral. The impact of adhering to these timeliness recommendations in the real-world setting is unknown. Method(s): The Victorian Lung Cancer Registry, a multicentre lung cancer clinical quality registry, was analysed to identify patients with newly-diagnosed ES-SCLC. The referral-to-diagnosis interval (RDI), referral-totreatment interval (RTI) and diagnosis-to-treatment interval (DTI) were calculated and, in line with OCP guidelines, defined as timely if they were less than 28 days, 42 days and 14 days, respectively. The impact of timeliness on overall survival was determined using univariate and multivariable Cox proportional hazards regression and propensity score matching. Result(s): From January 2012 to April 2023, there were 995 evaluable patients with ES-SCLC who were treated with chemotherapy, with a median age was 68 years (interquartile range (IQR) 61-74 years). 59.8% were male. The median RDI, RTI and DTI were 8 days (IQR 4-17 days), 18 days (IQR 10-31 days) and 7 days (IQR 4-13 days), respectively. Overall survival was worse when the DTI was <14 days compared to >=14 days, with hazard ratios (HR) of 1.31 (95% confidence interval (CI) 1.12-1.54, p=0.001) in the univariate analysis, a 1.32 (95% CI 1.13-1.56, p=0.001) in the multivariable analysis and 1.30 (95% CI 1.07-1.58, p=0.008) in the propensity score-adjusted analysis. Shorter RDI and RTI were also associated with poorer survival. Using multivariable regression, the HR for RDI <28 days relative to RDI >=28 days was 1.37 (95% CI 1.10-1.71, p=0.005), while the HR for RTI <42 days relative to RTI >=42 days was 1.58 (95% CI 1.28-1.95, p<0.0001). Conclusion(s): The majority of patients received care that met defined timeliness targets, but earlier diagnosis and treatment were associated with poorer survival. This may be explained by unmeasured confounders. Delivery of timely care may also have benefits on symptom burden and quality of life, but these factors were not prospectively captured in our registry data.