Net Survival Following Lung Cancer Resection in North West England: A Pohar–Perme Estimator Analysis

Introduction

Long-term survival studies need to be interpreted relative to background population mortality. Net survival, estimated with the Pohar–Perme method, provides an unbiased cancer-specific survival measure by adjusting for competing risks of death. We report population-adjusted long-term survival outcomes after lung cancer resection in a regional cohort undergoing curative-intent lung resection.

Methods

We analysed a consecutive cohort of patients with primary lung cancer treated surgically between 2012 and 2019 at two major thoracic centres in North West England. Patient data were linked with UK life tables from the Human Mortality Database to derive expected survival by sex, age, and calendar year. Net survival was estimated using the Pohar–Perme method implemented in the relsurv package in R. Follow-up time and patient age were expressed in years, with results reported at 1–5 years post-surgery.

Results

A total of 3,426 patients were included, with a median follow-up of 6.2 years. Stage I and II disease accounted for 37% and 40% of cases, respectively. There were 1,996 (59%) observed deaths versus 871 expected background mortality, corresponding to 1,125 excess deaths. Observed overall survival was 95.9% at 1 year, 79.2% at 3 years, and 62.4% at 5 years. Net survival, adjusted for background mortality, was higher at all timepoints, measuring 98.8% (95% Confidence Interval [CI] 98.2–99.4) at 1 year, 93.7% (95% CI 92.5–94.9) at 3 years, and 85.8% (95% CI 84.1–87.5) at 5 years. The overall standardized mortality ratio (SMR) was 2.29 (95% CI 2.19–2.39).

Conclusion

Population-adjusted net survival highlights the true mortality burden of lung cancer. Our findings show that surgery in carefully selected early-stage lung cancer achieves excellent outcomes, underscoring the sustained benefit of surgical management after adjusting for background mortality. These results provide a robust benchmark for future comparisons across regions and treatment eras.