Mortality and cancer incidence among physicians of traditional Chinese medicine: A 20-year national follow-up study

Objective: To study the risks of mortality and cancer incidence in physicians of traditional Chinese medicine (TCM) who had frequent exposure to herbal medicine. Methods: A population-based cohort design was conducted in which a total of 7675 certified physicians of TCM who ever practised between 1985 and 2005 were compared with the age-, sex- and calendar year-specific mortalities and cancer incidence rates of the general population of Taiwan. The age-, sex- and calendar year-standardised mortality ratio (SMR) and standardised cancer incidence ratio (SIR) were calculated to estimate the relative risks of all causes and site-specific mortality and cancer incidence. Results: Over an up to 20-year observational period, 796 (10.4%) physicians of TCM died, and 279 (3.6%) developed cancer. The study cohort showed a significantly reduced SMR for all-causes mortality (68, 95% CI 63 to 73), and for deaths from infectious (SMR = 64), circulatory (SMR = 68), respiratory (SMR = 64) and digestive (SMR = 56) disease. The study cohort also had a significantly reduced SIR (80, 95% CI 71 to 90) for all cancers, and for neoplasm of rectum, rectosigmoid junction, and anus (SIR = 45), female breast (SIR = 30) and cervix uteri (SIR = 10). On the other hand, we noted that physicians of TCM suffered from a significantly increased SIR for neoplasm of liver and intrahepatic bile ducts (SIR = 151, 95% CI 116 to 192) and of bladder cancer (SIR = 259, 95% CI 167 to 382). Conclusion: Like other healthcare workers, we noted that physicians of TCM had significantly reduced risks of all-causes mortality and cancer incidence. Nonetheless, reasons truly responsible for significantly increased risks of liver and bladder neoplasm among physicians of TCM warrant further investigations.