2.7. Sample size consideration
The study aims to enroll 40 patients with OPC or HPC who will be treated with CRT or RT over 4 years. The target number of cases was set based on feasibility, given that approximately 12 patients are treated annually with these therapies at the institution. If the average ± SD expected to change in the primary endpoint maximum TP is estimated to be 15.0, the width of the 95% confidence interval (CI) will be appropriately 4.0 ± 2.0 based on a previous study.