Cancer Incidence among Healthcare Workers in Cancer Centers: A 14-Year Retrospective Cohort Study in Thailand

OBJECTIVE: To identify the situation and possible work-related cancer risks among healthcare workers in cancer centers. METHODS: This research was a 14-year retrospective cohort study of 2,331 healthcare workers at the National Cancer Institute and 7 regional cancer centers in Thailand. The study period consisted of a total of 18,939 person-years of observation. The demographic data, such as occupation and work area were collected by self-administered questionnaires or by use of a proxy. The cases were identified by the diagnoses of physicians. The incidence rates for each type of cancer, occupation and work area among the population of this study were compared with the general working population, based on national cancer statistics. The results were reported in terms of Standard Incidence Ratio (SIR) and a 95% confidence interval (CI), using Fisher’s exact method. FINDINGS: There were 12 different types of cancer identified in 35 cases during the 14 years of the study and breast cancer was found to be at the highest number. The overall cancer incidence rates were 221.04 and 173.43 per 100,000 person-years, in males and females, respectively. Leukemia showed statistically significant levels of high SIR among the female healthcare staffs (SIR = 11.54; 95% CI = 2.38–33.72). With regard to occupation, only the male physicians showed significant SIR = 6.02; 95% CI = 1.41–19.93, while this study did not identify significant SIR levels in any of the work areas. CONCLUSIONS: This study found that the risk of leukemia was higher than expected among healthcare workers and that physicians may have an increased risk of cancer compared to the general working population, which may be a work-related reflex. However, interpretations should be made with caution due to the small number of cases.