Estimating the impact of cancer diagnosis on life expectancy by stage at diagnosis: population-based estimates for a range of cancer sites in England

Objective Unlike survival measures, life expectancy readily illustrates the burden of cancer on society and the average impact on individuals diagnosed with cancer. Cancer stage at diagnosis is a key prognostic factor and hence it is important to obtain stage-specific life expectancy estimates. However, completeness of recording for cancer stage at diagnosis is often historically poor in cancer registries. Therefore, it can be challenging to obtain the long-term stage-specific survival estimates required for estimating stage-specific life expectancy. We provide the first stage-specific life expectancy estimates using whole population data in England.Methods and analysis Multiple imputation was used to impute values of cancer stage at diagnosis for patients with missing stage at diagnosis information. The simultaneous application of period analysis to obtain up-to-date estimates restricts the contribution of patients with historical diagnoses and hence improves the overall completeness of stage at diagnosis information. For each of the 10 cancer sites in this study, we fit a flexible parametric excess hazard model for each cancer stage on the cumulative excess hazard scale and estimated stage-specific life expectancy using the relative survival framework.Results The differences in stage-specific and sex-specific life expectancy were evaluated from 40 to 90 years of age. Colorectal cancer, prostate cancer and bladder cancer yield much lower estimates of life expectancy for patients diagnosed with stage IV cancer compared with stages I–III. For example, female patients diagnosed with stage IV colorectal cancer at 70 years of age have a life expectancy of 72.3 years, while those with stages I–III can expect to live beyond 82.0 years. The remaining cancer sites yield approximately equal reductions in life expectancy with each increase in stage at diagnosis from I to IV.Conclusion We offer the first stage-specific life expectancy estimates for a range of cancer sites in England using data from the National Cancer Registration and Analysis Service, with follow-up until February 2020. Estimates of stage-specific life expectancy provide a real-world, intuitive metric to evaluate the impact of cancer stage at diagnosis on prognosis up to a lifetime horizon. Stage-specific life expectancy estimates also provide key information regarding the potential benefits of early diagnosis initiatives in terms of gains in life years.