Incidence risks of malignant tumor among medical diagnostic X-ray workers during 1950–2011 in Jiangsu, China

Abstract

Objective To study the relationship between the risk of malignant tumor and occupational radiation factor among medical diagnostic X-ray workers in Jiangsu province. Methods The retrospective and prospective cohort studies were adopted to investigate the incidence of cancer. Eligible medical diagnostic X-ray workers from the department of radiology in hospitals were selected and assigned into exposure group, while other medical workers from the departments of Internal Medicine, Ear-Nose-Throat (ENT) or Pediatrics who attended work at the same period in the same hospital but not engaged in radiation work were regarded as control group during 1950–2011 in Jiangsu province. We calculated the total person-year and analyzed the relative risk (RR) of malignant tumor using Poisson regression model. Results 7 703 participants (3 961 in exposed group and 3 742 in unexposed group) were recruited and followed up, with a total of 315 309 person years and the lost follow-up rate was 6.92% (533/7 703). During the follow up period, a total of 819 tumor cases were identified (771 were malignant tumors). We found the significant relationship between the risk of malignant tumor and occupational radiation factor, and the RR of solid cancer and total malignant tumor were 1.31 (95%CI: 1.11–1.55) and 1.33 (95%CI: 1.13–1.57), respectively. In addition, the risk of lung cancer in medical diagnostic X-ray workers was significantly higher than that in control group (RR=1.45, 95%CI: 1.00–2.09). Conclusions The incidence risk of lung cancer, solid caner and total malignant tumors in medical diagnostic X-ray workers was significantly higher than that in the control group, which might be associated with occupational exposure to ionizing radiation. Key words: Medical X-ray workers; Cohort study; Malignant tumor; Relative risk; Radiation carcinogenesis