Ultraviolet Light Exposure Decreases Thyroid Cancer Risk: A National Perspective.

Ultraviolet (UV) light has been reported to have both pro-oncogenic and anti-oncogenic effects. Since patient pigmentation can influence the role of UV light exposure, we thought to investigate the recent trends in thyroid cancer incidence and survival with an emphasis on patient race and UV exposure. Patients diagnosed with thyroid cancer from the Surveillance, Epidemiology, and End Results (SEER) database were identified. A total of 284,178 patients were enrolled. Data were stratified according to population sex, race, and state. UV exposure data in Watt-Hours Per Square Meter for the state were obtained from the National Cancer Institute Cancer Atlas. Thyroid cancer incidence rate varied by race, ranging from 14.9 cases per 100,000 in Asian or Pacific Islanders and 14.7 per 100,000 in Caucasians, to 8.7 per 100,000 in African American and 8.0 per 100,000 in Native Americans. UV exposure was negatively correlated with thyroid cancer incidence when analyzed across all populations (r = −0.299, p = 0.035). UV exposure was most steeply negatively correlated with thyroid cancer rates in Black populations (r = −0.56, p < 0.001). Despite this, Black men had the worst 5-year survival rate when compared to other ethnic populations. Overall, UV exposure does not increase the risk of thyroid cancer and may serve as a protective factor in the development of thyroid cancer.