Study Indicates That Anti-Diabetic Therapies Do Not Increase Cancer Risk

Exposure to insulin glargine and metformin did not cause increased risk of cancer or worse cancer outcomes, according to a study presented in an oral presentation at the American Diabetes Association 73^rd Scientific Sessions in Chicago, IL.

However, new cases of diabetes were associated with an increased incidence of cancer, according to abstract 281-OR, “Cancer Outcomes in Patients with Dysglycemia on Basal Insulin: Results of the ORIGIN Trial.”

“Daily exposure to glargine for 6.2 years had a neutral effect on new cancers, any cancer, cancer mortality, and type of cancer,” said Louise Bordeleau, MD, of McMaster University in Hamilton, Ontario, who presented the Sanofi-sponsored study.

The study was a sub-analysis of an experiment that looked for a relationship between dysglycemia and basal insulin, which was presented at the ADA’s 2012 meeting, and which was published in the New England Journal of Medicine, Bordeleau said.

In the original study (the ORIGIN trial), 12,537 participants with either diabetes or pre-diabetes, but without any active cancers, and who were at high risk for cardiovascular disease were randomized to receive either insulin glargine or standard care, and omega-3 fatty acids or placebo, according to the abstract. The study population had a mean age of 63.5 years, and 35% of them were female. Median follow-up was 6.2 years. Of the participants, 82% had prior diabetes, with a mean duration of 5.4 years.

All told, 953 individuals, or 7.6% of the participants, developed a cancer event, amounting to 1.32 cancer events per 100 person-years, for both the insulin glargine and standard care groups, according to the abstract. The unadjusted rate of cancer death was 0.54 deaths per 100 person-years in the standard therapy group, compared to 0.51 deaths per 100 patient years among those who received glargine. There was no significant difference in outcomes for lung, breast, prostate, and colon cancers or melanoma.

The rate of death among those who developed cancer was 94%. For lung cancer the rate was 22%, but for those who used glargine and developed cancer, it was only 18%.

The rate of cancer among those who used metformin was slightly higher, with a hazard ratio of 1.08. For breast cancer, the hazard rate of those who used metformin was 0.16. Metformin use also increased during the course of the trial, Bordeleau noted.

“Weaknesses of the study include the relatively low incidence of cancer among participants. On the other hand, the investigators made use of blinded adjudication of cancer events,” according to Bordeleau. The findings for all clinical subgroups had an interaction p value of less 0.17.

Neither body-mass index nor HbA1c were associated with a higher incidence of cancer, according to the abstract. However, participants who experienced a cancer event during the study tended to be older, had a higher frequency of smoking and alcohol intake, and were more likely to have a previous cardiovascular event, the abstract said. In addition, cancer was associated with statin or aspirin use.