The risk of basal and squamous cell carcinomas of the skin cancer incidence and external radiation in the updated National Registry for radiation workers cohort in the <scp>UK</scp>

This study presents the most comprehensive evaluation to date of non-melanoma skin cancer (NMSC) risk in the UK National Registry for Radiation Workers, examining separately both basal cell carcinoma (BCC) and squamous cell carcinoma (SCC). The cohort includes 172,452 workers with over 5.3 million person-years of follow-up (1955-2011) and a mean cumulative dose of 24.9 mSv. Cumulative external radiation was assessed using the personal dose equivalent Hp(10), and Poisson regression estimates the excess relative risk per Sievert (ERR/Sv) of skin cancer incidence. A total of 5748 NMSC cases were identified (4288 BCC, 818 SCC). BCC showed good evidence of a linear dose-response (ERR/Sv = 0.85, 95% CI: 0.39-1.39; p <.001), but this weakened after adjusting for anatomical location as a proxy for ultraviolet radiation (UVR) exposure (ERR/Sv = 0.15; 95% CI: -0.17-0.54; p = 0.28). However, BCC risk remained elevated among workers who were monitored for internal exposure and those workers first employed before 1960, both of whom experienced higher doses and longer follow-up. SCC showed only limited evidence of a radiation dose-response (ERR/Sv = 0.87; 95% CI: 0.03-2.05; p = 0.04), driven largely by a small number of cases at high dose, and lost significance after adjustment for anatomical location. Most BCC and SCC tumors occurred on sun-exposed areas, with notably higher BCC risks on the upper limbs. These findings highlight the importance of accounting for UVR exposure in occupational radiation studies of skin cancer and support further research with individual UVR exposure data and skin dose data to better quantify these risks.