Highlights
– In 25,723 five‑year childhood cancer survivors (median follow‑up 28.5 years), colorectal subsequent malignant neoplasms (SMNs) were strongly associated with mean colorectum dose (MCD) and irradiated colorectal volume in a dose‑dependent manner.
– Specific chemotherapy exposures showed independent and dose‑dependent risks: procarbazine demonstrated a steep linear excess rate ratio (ERR) per 1,000 mg/m2, and high cumulative doses of alkylators and platinum were also associated with markedly increased colorectal SMN incidence.