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Abstract
Background The dose–response relationship between cancers and protracted low-dose rate exposure to ionising radiation is still uncertain. This study aims to estimate quantified relationships between low-dose radiation exposures and site-specific solid cancers among Chinese medical X-ray workers.
Methods This cohort study included 27 011 individuals who were employed at major hospitals in 24 provinces in China from 1950 to 1980 and had been exposed to X-ray equipment, and a control group of 25 782 physicians who were not exposed to X-ray equipment. Person-years of follow-up were calculated from the year of employment to the date of the first diagnosis of cancer or the end of follow-up, whichever occurred first. All cancers were obtained from medical records during 1950–1995. This study used Poisson regression models to estimate the excess relative risk (ERR) and excess absolute risk (EAR) for incidence of site-specific solid cancers associated with cumulative dose.
Results 1643 solid cancers were developed, the most common being lung, liver and stomach cancer. Among X-ray workers, the average cumulative colon dose was 0.084 Gy. We found a positive relationship between cumulative organ-specific dose and liver (ERR/Gy=1.48; 95% CI 0.40 to 2.83), oesophagus (ERR/Gy=18.1; 95% CI 6.25 to 39.1), thyroid (ERR/Gy=2.96; 95% CI 0.44 to 8.18) and non-melanoma skin cancers (ERR/Gy=7.96; 95% CI 2.13 to 23.12). We found no significant relationship between cumulative organ-specific doses and other cancers. Moreover, the results showed a statistically significant EAR for liver, stomach, breast cancer (female), thyroid and non-melanoma skin cancers.
Conclusions These findings provided more useful insights into the risks of site-specific cancers from protracted low-dose rate exposure to ionising radiation.
- epidemiology
- radiation, ionizing
- occupational health
Data availability statement
Data are available upon reasonable request. Data cannot be made publicly available because public availability would compromise participant privacy. For data access, researchers can contact the Institute of Radiation Medicine Chinese Academy of Medical Sciences & Peking Union Medical College, Tianjin, China (E-mail address: liuqiang@irm-cams.ac.cn).
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Data availability statement
Data are available upon reasonable request. Data cannot be made publicly available because public availability would compromise participant privacy. For data access, researchers can contact the Institute of Radiation Medicine Chinese Academy of Medical Sciences & Peking Union Medical College, Tianjin, China (E-mail address: liuqiang@irm-cams.ac.cn).
Footnotes
YG and JW are joint first authors.
YG and JW contributed equally.
Contributors YG, JW, KN and QL contributed to the study conception and design; manuscript drafting; manuscript revising. YG, JW, YW, CX, YL, LD, QW, KJ, NH, MZ, HS, KN and QL contributed to data collection, assembly, analysis and interpretation of the data. QL accepts full responsibility for the work and/or the conduct of the study as guarantor, had access to the data, and controlled the decision to publish. All authors approved the final version of the manuscript.
Funding This work was supported by the CAMS Innovation Fund for Medical Science (2021-I2M-1-042); National Natural Science Foundation of China (82103837, 31971168, 81972976, 32071241, 32171239 and 82072331).
Competing interests None declared.
Provenance and peer review Not commissioned; externally peer reviewed.
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