Conditional survival rates of buccal and tongue cancer patients: How far does the benefit go?

SummaryThe purpose of this study was to investigate the conditional survival probability in buccal and tongue cancer patients, and to identify the limit of increment in conditional survival probabilities after first diagnosis. This study retrospectively analyzed 339 consecutive patients with either buccal or tongue caner. The conditional survival probability was computed by Kaplan–Meier estimates, and the pair-wise Log-rank tests with Bonferroni correction were used to evaluate differences among conditional survival curves. It was found that the 3-year conditional survival rates for successive years of survival were 55.5%, 69.9%, 74.1% and 77.8%. The conditional survival curves started to become significantly better than the original survival curve at the twelfth month, and those curves after 24 months of survival were not significantly different from each other. Many previous studies have described the benefit of conditional survival probabilities for personalized information on better chance of survival, but only reported conditional survival probabilities and statistical tests for point-wise estimates. In this study, a new approach was adopted to conclude that the idea of conditional survival probability is best for the first 2 years in buccal and tongue cancer patients, and any longer survival time would not make significant difference in survival rates. The idea of pair-wise log-rank tests on conditional survival curves can provide statistical evidence for the critical time frame of survival in many different cancers.