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Large European, US studies find no insulin glargine–cancer connection
PHILADELPHIA — After conducting three large-scale studies in Europe and the United States, researchers have found no increased risk for cancer associated with relatively short-term use of insulin glargine, according to data presented here at the American Diabetes Association’s 72nd Scientific Sessions.
This latest finding contradicts studies published in 2009 that reported that there was a correlation between cancer risk and use of insulin glargine (Lantus, Sanofi-Aventis), researchers said during a presentation.
“At the end of the day, I am satisfied with the safety in glargine in regards to cancer,” said John Buse, MD, PhD, director of the Diabetes Center at the University of North Carolina School of Medicine.
US analyses
Two studies were conducted in the US; one at the University of North Carolina and one at Kaiser Permanente in Northern and Southern California. Both US studies examined the risk for breast, prostate and colorectal cancers, as well as all cancers combined, among patients with diabetes using insulin glargine vs. those using neutral protamine Hagedorn (NPH) insulin.
Buse and Til Stürmer, MD, MPH, PhD, professor of epidemiology and director of the Center of Excellence in Pharmacoepidemiology and Public Health at the University of North Carolina Gillings School of Global Public Health, identified approximately 43,000 “new users of glargine,” and 9,000 new users of NPH. This study used data from the MedAssurant US health care insurance databases and electronic medical records from Louisiana and Massachusetts
According to the data, when comparing new glargine users vs. new NPH users overall, the RR for breast cancer was 1.1; the RR for prostate cancer was 1.2; for colorectal cancer, it was 0.9; and for all cancers, the risk was 1.1.
Buse said the CIs varied, but overall, they found no statistically significant signal regarding cancer risk among glargine users, including among those with long-standing use. However, there were only 14 breast cancer events among long-standing users of glargine or NPH.
Laurel Habel, PhD, senior research scientist at Kaiser Permanente Northern California Division of Research and a lecturer at Stanford University School of Medicine in the department of health research and policy, was principal investigator of the California study.
That study was conducted among 730,000 Kaiser Permanente patients aged 18 years and older with diabetes, no history of cancer and at least 12 months of continuous membership in the health plan. Habel said there were 27,000 patients who had used glargine since May 2001, when glargine was introduced to the US market, compared with 100,000 users of NPH during this same period.
Researchers also conducted analyses among new insulin users — about 6,500 new users of glargine and 40,000 new users of NPH. Patients in the study had a median follow-up of 3.3 years.
Habel and colleagues examined the risk for cancer among new insulin users and among those who had switched from NPH to insulin glargine. The median duration of use was 1.2 years for glargine and 1.4 years for NPH. According to Habel, about 75% of glargine users had used non-glargine insulin before initiating insulin glargine.
The researchers found no evidence of an increased risk for cancer when users of NPH switched to insulin glargine. However, among new insulin users, there was a modest increase in the risk for breast cancer associated with 2 or more years of insulin glargine use (HR=0.9; 95% CI, 0.6-1.4), compared with 2 years of glargine use (HR=1.6; 95% CI, 1.0-2.8) vs. use of NPH, but Habel said this was “borderline statistically significant.”
“In conclusion, we found that switching to glargine from NPH or initiating glargine vs. initiating NPH was not associated with an increased risk of prostate, colorectal or all cancers combined,” Habel said.
Since it can take many years for cancer to develop, Habel added that her cohort — and those included in other studies — must be followed for a longer duration to determine whether insulin glargine might be associated with cancer risk, and all results should be viewed cautiously.
Northern European data
Peter Boyle, PhD, president of the International Prevention Research Institute in Lyon, France, conducted a study composed of 447,821 patients with diabetes who were taking insulin and had 17,800 new cases of cancer during the time of the study. Researchers observed 1.5 million person-years of exposure; with 3.1 years follow-up on glargine, and 3.5 years for other insulin, Boyle said.
Similar to the studies conducted by Habel, Buse and Stürmer, the Northern European Database Study of Insulin and Cancer Risk examined the same endpoints: risk for breast cancer in women, prostate cancer in men, colorectal cancer in men and women and all other cancers.
Additionally, researchers compared all forms of cancer combined in adults taking insulin glargine vs. those taking all other types of insulin. They found no indication for the risk for lung or pancreatic cancers — besides breast, prostate and colorectal cancers — among insulin glargine users.
Boyle and colleagues also conducted a meta-analysis based on reports from epidemiological studies that included 907,008 patients and 2,597,602 person-years of observation. The summary relative risk (SRR) for all forms of cancer, based on 13 studies examining glargine vs. non-glargine insulin, was 0.9 (95% CI, 0.82-0.99), and for breast cancer, it was 1.11 (95% CI, 1.00-1.22).
Among new users of glargine, identified in six studies, the SRR for breast cancer was 1.3 (95% CI, 0.93-1.81). Based on eight studies for colorectal cancer, the SRR was 0.84 (95% CI, 0.74-0.95), and for prostate cancer, it was 1.13 (95% CI, 1.00-1.28).
“There was absolutely no evidence of an increased risk of cancer, in all its forms, associated with the use of glargine compared to other medicines,” Boyle said.
These three studies were supported by grants from Sanofi. – by Samantha Costa
For more information:
- Boyle P. Abstract CT-SY13. Northern European database study of insulin and cancer risk.
- Buse J. Abstract CT-SY13. What we know about insulin and cancer.
- Habel L. Abstract CT-SY13. Results from Kaiser-Permanente collaboration.
- Stürmer T. Abstract CT-SY13. Results from claims data and a focus on incident user analysis.
- All four abstracts presented at: the American Diabetes Association’s 72nd Scientific Sessions; June 8-12, 2012; Philadelphia.
Disclosures:
- Dr. Boyle reports research support from Sanofi-Aventis.