This is Episode 6: Foundations V — Fractionation and Time: Why We Don’t Treat Head and Neck Like Prostate.In prostate cancer, a week off for a holiday can be inconvenient, but the tumor biology barely flinches. In head and neck squamous cell carcinoma, a week off is not “just a delay.” It is a biological advantage handed to the tumor.Today is the Time Factor episode: overall treatment time, accelerated repopulation, altered fractionation, and—most important for oral boards—what you actually do when treatment gets interrupted.