Hashimoto thyroiditis (HT) is not a significant risk factor for melanoma or nonmelanoma skin cancer (NMSC), according to study results published in the Archives of Dermatological Research.
Risk for ulcerated cutaneous melanoma is increased by an inflammatory microenvironment, suggesting a relationship between melanoma and a pro-inflammatory state. Therefore, researchers sought to evaluate whether HT, which often causes chronic systemic low-grade inflammation, is a risk factor for developing melanoma skin cancer. Development of melanoma and time to first melanoma diagnosis were the primary study outcomes.
In a retrospective control-matched study, the researchers extracted data from the Olmsted County (Minnesota, US) database of electronic medical records between 2005 and 2020. They identified 4805 patients at least 18 years of age for inclusion. The first group comprised 1726 patients (mean [SD] age, 45.8 [17.1] years; 83.6% White, 3.4% Asian, 2.0% Black) with HT, while the second group (control) comprised3079 patients without HT (mean age, 46.5 [17.1] years, 79.9% White, 5.3% Asian, 5.1% Black). Patients were sex- and age-matched in a 1.78:1 ratio of patients in the control group to patients with HT. Patients diagnosed with other autoimmune diseases were excluded from the study.
During a median follow-up of 9.6 years (interquartile range, 6.4-13.7), there were 387 deaths overall.
The researchers found no significant difference in risk for melanoma in patients with HT vs those in the control group (relative risk [RR], 0.96; 95% CI, 0.78-1.17; P =.66), and no significant difference in risk for NMSC diagnosis in those with HT (23.2%) vs control group (24.3%; RR, 0.95; 95% CI, 0.86-1.06). The prevalence of melanoma among patients with HT was slightly less than that among the control group (7.8% vs 8.2%, respectively).
The researchers found no significant difference in time to first diagnosis (hazard ratio, 0.94; 95% CI, 0.76-1.15; P =.54).
Study limitations include its retrospective design; lack of data stratification for such factors as treatment types, which may confound cancer risk; and the inclusion of patients from only 1 region in the US.
“Although numerous studies have identified links between autoimmune diseases and melanoma, we did not find evidence that HT contributes to melanoma risk,” the researchers concluded. They wrote, “It is possible the local and low-grade systemic inflammation in HT is not enough to create the proinflammatory milieu that is associated with melanoma,” adding that “dermatologists should still counsel these patients about other individual factors which may impact their risk of skin cancer, especially immunosuppressive therapies patients with HT may be prescribed.”
References:
Gorman BG, Campbell E, Mullen BL, et al. Association between Hashimoto’s thyroiditis and melanoma: a retrospective matched cohort study. Arch Dermatol Res. Published online July 21, 2023. doi:10.1007/s00403-023-02669-4
