SKIN MELANOMA INCIDENCE IN WORKERS OCUPATIONALLY EXPOSED TO IONIZING RADIATION OVER A PROLONGED PERIOD

Abstract

Purpose of the study. The study is aimed to investigate skin melanoma incidence in workers occupationally exposed to radiation over a prolonged period. Materials and methods. Skin melanoma incidence was studied in a cohort of workers first employed at nuclear facility Mayak Production Association (PA) between 1948 and 1982 who had been followed up till 31.12.2013 (22,377 individuals). Mean cumulative doses from external gamma-rays over the whole follow-up period were 0.54±0.001 Sv in males and 0.44±0.002 Sv in females. Incident rates for skin melanoma were analyzed by sex, attained age, calendar period of diagnostics and radiation dose using worldwide standard and the direct standardization technique. Results. 60 skin melanoma cases (37 in males and 23 in females) were registered in the study cohort over the whole follow-up period. The standardized skin melanoma incident rate was 8.51±1.46 in males and 8.78±2.27 in females per 100000 workers revealing statistically higher rates compared to corresponding rates for general populations of the Russian Federation, Urals Federal District and Chelyabinsk region. Skin melanoma incidence was significantly increased in the period of 1994 - 2013 as compared to the period of 1974 - 1993. Skin melanoma incidence excess in females was greater than that for males. Skin melanoma incidence increment in females was mostly driven by modifications of disease occurrence risk while in males it was driven by a combined effect of age pattern modifications in the study cohort and increase of disease risk. Conclusions. Skin melanoma incidence rates in the cohort of workers occupationally exposed to ionizing radiation over a prolonged period were associated with sex and attained age workers and the calendar period of diagnostics. No significant association of skin melanoma incidence with dose from external gamma-rays was observed. A significantly increasing trend was observed for skin melanoma incidence by the end of the follow-up in both males and females.