# Is Radiotherapy a Risk Factor for Melanoma?

## TL;DR

Radiotherapy, especially in childhood, may increase the risk of developing melanoma, suggesting a need for long-term monitoring of irradiated areas.

## Contribution

This review clarifies the potential link between radiotherapy and melanoma, emphasizing risks in pediatric patients and the need for targeted surveillance.

## Key findings

- Childhood radiotherapy, even at low doses, is associated with increased melanoma risk due to radiosensitive developing melanocytes.
- Occupational radiation exposure in earlier eras correlates with elevated melanoma risk.
- Adult radiotherapy shows mixed evidence, with some data suggesting a modest melanoma risk increase.

## Abstract

Melanoma is a highly aggressive skin cancer primarily linked to ultraviolet (UV) radiation. However, the potential role of ionizing radiation from radiotherapy in melanoma development remains unclear. This review synthesizes data from epidemiologic studies and case reports on melanoma after radiation exposure. Evidence indicates that childhood radiotherapy, even at low doses, is associated with an increased melanoma risk, plausibly reflecting the heightened radiosensitivity of developing melanocytes. Occupational radiation exposure, particularly in earlier eras with insufficient shielding, also appears to elevate risk. In patients exposed to radiation in adulthood, findings are mixed: large population datasets suggest a modest increase in melanoma following therapeutic radiation, whereas some case–control analyses do not demonstrate a clear dose–response relationship. UV radiation promotes melanomagenesis through direct DNA photoproducts driving characteristic C>T transitions at dipyrimidine sites, alongside oxidative stress and local immune modulation that facilitate malignant transformation. Collectively, individuals with prior radiotherapy, especially those irradiated in childhood, should be considered at increased melanoma risk and may benefit from long-term, targeted surveillance of irradiated fields. Awareness of this association between radiation exposure and melanoma may also support clinicopathologic correlation during the diagnostic evaluation of melanocytic lesions. Future work should define dose–response relationships in contemporary radiotherapy methods, characterize molecular signatures of ionizing radiation-associated melanomas, and establish evidence-based surveillance strategies for high-risk cohorts.