Decreased risk of colorectal cancer among patients with type 2 diabetes receiving Chinese herbal medicine: a population-based cohort study

OBJECTIVES: Patients with type 2 diabetes have a higher risk of colorectal cancer (CRC), but whether Chinese herbal medicines (CHMs) can reduce this risk is unknown. This study investigated the effect that CHMs have on CRC risk in patients with type 2 diabetes. RESEARCH DESIGN AND METHODS: This cohort study used the Taiwanese National Health Insurance Research Database to identify 54 744 patients, newly diagnosed with type 2 diabetes, aged 20–70 years, who were receiving treatment between 1998 and 2007. From this sample, we randomly selected 14 940 CHMs users and 14 940 non-CHMs users, using propensity scores matching. All were followed through 2012 to record CRC incidence. Cox proportional hazards regression was used to compute the hazard ratio (HR) of CRC by CHMs use. RESULTS: During follow-up, 235 CHMs users and 375 non-CHMs users developed CRC, incidence rates of 1.73% and 2.47% per 1000 person-years, respectively. CHM users had a significantly reduced risk of CRC compared with non-CHM users (adjusted HR=0.71; 95% CI 0.60 to 0.84). The greatest effect was in those receiving CHMs for more than 1 year. Huang-Qin, Xue-Fu-Zhu-Yu-Tang, Shu-Jing-Huo-Xue-Tang, Liu-Wei-Di-Huang-Wan, Ji-Sheng-Shen-Qi-Wan, Gan-Lu-Yin, Shao-Yao-Gan-Cao-Tang and Ban-Xia-Xie-Xin-Tang were significantly associated with lower risk of CRC. CONCLUSION: Integrating CHMs into the clinical management of patients with type 2 diabetes may be beneficial in reducing the risk of CRC.