Conditional survival analysis of four treatment strategies for patients with stage I non-small cell lung cancer

Conditional survival (CS) is used to describe dynamic survival possibility, taking account of the change in the survival risk that occurs with longevity. The present study aimed to explore the CS of four treatment strategies for stage I non-small cell lung cancer (NSCLC), staged according to the eighth edition of the American Joint Committee on Cancer/Union for International Cancer Control NSCLC staging system. Using the Surveillance, Epidemiology and End Results Program cohort obtained between 2004–2014, the current study first extracted data for 27,116 patients with stage I NSCLC. The actuarial cancer-specific survival rates (ACSs) and conditional cancer-specific survival rates of four treatment strategies were then compared. ACS was assessed using the Kaplan-Meier method and a log-rank test. The 3-year conditional cancer-specific survival (CCS3) of patients who had already survived for n years was calculated as CCS3=ACS(n+3)/ACS(n). Cox regression and propensity-score matching (PSM) was applied to adjust confounding factors. The 5-year ACS of patients who underwent lobectomy, sublobar resection, radiation and observation was 80.3, 72.0, 40.8 and 19.6%, respectively. The 5-year CCS3 of patients who underwent lobectomy, sublobar resection, radiation and observation was 91.7, 86.4, 77.0 and 58.2%, respectively. CCS3 increased with an increase in survival time and patients who underwent lobectomy had the highest CCS3 estimates and flattest growth, with the smallest survival gap between CCS3 and ACS. The results were similar in the PSM analysis. In conclusion, CS estimates may provide a more accurate survival prediction for patients with stage I NSCLC, and may assist with treatment decisions and surveillance strategies. In addition, the current study provided evidence that suggests lobectomy may be the optimal treatment strategy for stage I NSCLC compared with sublobar resection.