Acarbose may protect against colorectal cancer

Last Updated: 2015-09-07

By Reuters Staff

NEW YORK (Reuters Health) - Diabetes patients who take the alpha-glucosidase inhibitor acarbose may be reducing their risk of developing colorectal cancer (CRC), researchers suggest.

In an observational population-based study from Taiwan, patients using acarbose had a 27% reduced risk of CRC compared with those who did not use the drug, with clear dose-response effects, according to Dr. Pau-Chung Chen from National Taiwan University College of Public Health in Taipei and colleagues.

A recent in vitro study had suggested antineoplastic effects of acarbose, they noted online August 25 in Diabetes Care. And in a mouse model of multiple intestinal adenomas, acarbose had a "regressive effect on the size of gastrointestinal adenomas but did not significant decrease the number of colonic neoplasms," they note. Yet prior small observational studies have yielded inconsistent results on acarbose use and CRC.

Using the Taiwan National Health Insurance Research Database, they identified more than 1.3 million people with diabetes, including 240,798 (17.9%) acarbose users. The median age at diagnosis of diabetes was 54.1 years and the median disease duration was 8.9 years.

During follow up of nearly 1.5 million person-years, 1,332 (0.33%) subjects developed CRC. The overall incidence was 89.6 cases per 100,000 person-years; it was 75.8 in acarbose users vs 103.8 in nonusers.

The risk of CRC was 27% lower in patients who had used acarbose compared with those who never did (crude hazard ratio 0.73, adjusted HR 0.66).

There was also a "significant trend" of reduced risk with increasing acarbose dose, the investigators report. The adjusted HRs were 0.73, 0.69, and 0.46 for patients using up to 89, 90 to 364, and 365 or more cumulative defined daily doses, respectively, compared with patients who didn't use the drug (P for trend <0.001).

The researchers note that a slower bowel transit time may account for increased CRC incidence in diabetes patients. "Delaying stool transit may alter the production and concentration of bile acids and contribute to DNA damage. Acarbose reduces the colonic transit time, and changes in the fecal concentration of bile acids may explain the protective effect against colorectal cancer development," they write.

One limitation of the analysis, they say, is not having data on potential confounding variables, such as body mass index, smoking, alcohol consumption, and physical activity, which are all associated with colorectal cancer.

The study had no commercial funding and the authors have no relevant disclosures. Dr. Chen did not respond to request for comment by press time.

SOURCE: http://bit.ly/1JMQZyB

Diabetes Care 2015.