Conditional survival in patients treated for gastric cancer with a curative intent

Background and Objectives Conditional survival (CS) provides the probability that a patient who has already survived a certain number of years after treatment will survive an additional number of years. We aim to study the CS of patients with gastric cancer. Methods Patients who underwent curative intent treatment for gastric cancer in a single institution between 2007 and 2018 were included in the analysis. The probability (CS) that a patient who has already survived x years will survive an additional y year, was calculated as CS (y/x) = S(x + y)/S(x). Results The probability of surviving an additional 3 years if a patient had already survived 1, 2, 3, 4, and 5 years after treatment were 64.2%, 74.5%, 81.6%, 83.2%, and 88.2%, respectively whereas the 4‐, 5‐, 6‐, 7‐, and 8‐year actuarial OS were only 47.2%, 43.2%, 41%, 39.4%, and 38.2%, respectively. The independent prognostic factors associated with poor survival were age >60 years, T stage ≥T3, N stage ≥N2, proximal tumor location, and lymph node ratio > 0.18. Patients with these high‐risk features showed the greatest increase in CS3 over time. Conclusion CS estimates provided a more dynamic prognostic information over time for patients treated for gastric cancer with curative intent.