In a study reported in a research letter in JAMA Network Open, Rezaei et al found that risk of melanoma and other nonkeratinocyte skin cancers was elevated in patients who had received radioactive iodine treatment for thyroid cancer.
Study Details
The study involved data from 17 Surveillance, Epidemiology, and End Results (SEER) registries on patients with primary thyroid cancer diagnosed from 2000 to 2019.
Among 174,916 patients included in the analysis, 79,576 (45.5%) had first-course treatment with some form of radiation. A total of 865 nonkeratinocyte skin cancers (790 melanoma) were diagnosed following thyroid cancer diagnosis, with 171 (19.8%) located on the skin of the head or neck.
Risk of nonkeratinocyte skin cancers was elevated in patients receiving radioactive iodine, with standardized incidence ratios (SIRs) of 1.42 (95% confidence interval [CI] = 1.29–1.57) for all cancers, 1.38 (95% CI = 1.24–1.53) for melanoma, and 2.02 (95% CI = 1.43–2.78) for other nonkeratinocyte cancers.
In analysis limited to cancer of the skin of the head and neck, SIRs were elevated for all nonkeratinocyte skin cancers (1.64, 95% CI = 1.32–2.02), melanoma (1.56, 95% CI = 1.22–1.97) and other nonkeratinocyte skin cancers (2.07, 95% CI = 1.23–3.27) among patients receiving radioactive iodine treatment. Risk of head and neck skin cancer was not elevated in patients who did not receive radioactive iodine.
Elevated risk of nonkeratinocyte skin cancers was observed among patients treated with any type of radiation for the papillary subtype of thyroid cancer (SIR = 1.69, 95% CI = 1.35–2.09). No significantly increased risks were observed for other subtypes, potentially due to small sample sizes.
The investigators concluded: “We found elevated risk of melanoma and other nonkeratinocyte skin cancers in patients with primary thyroid cancer who received radioactive iodine therapy, particularly in the head and neck region.”
Shawheen J. Rezaei, MPhil, of Stanford University School of Medicine, is the corresponding author for the JAMA Network Open article.
Disclosure: For full disclosure of the study authors, visit jamanetwork.com.
