In previous episodes, we've focused heavily on how radiation kills cancer cells and how normal tissues respond to therapeutic doses. Today, we shift our focus to a critical late effect of radiation exposure: the induction of cancer itself. Radiation, while a powerful tool against existing malignancies, is also a known carcinogen. We'll classify radiation carcinogenesis as a stochastic effect, explore the dose-response relationships for leukemia and solid tumors based largely on data from atomic bomb survivors, and understand the concept of latency periods. We'll also delve into the various factors that influence cancer risk from radiation and discuss the Linear No-Threshold (LNT) model, which underpins radiation protection philosophy, along with the DDREF concept used for risk extrapolation. Finally, we'll touch on the important clinical issue of secondary malignancy risk following radiotherapy.