Combined randomised controlled trial experience of malignancies in studies using insulin glargine

Recent publications of data extracted from population registries have suggested a possible relationship between treatment with insulin glargine and increased incidence of cancer/breast cancer. The aim of the present study was investigate this possible relationship using data from the manufacturer's (sanofi-aventis) pharmacovigilance database. We analysed the manufacturer's (sanofi-aventis) pharmacovigilance database for all randomised clinical trials (RCTs; Phase 2-4) comparing insulin glargine with any comparator in type 1 or type 2 diabetes. We identified all serious adverse events coded under the System Organ Class of 'neoplasms, benign, malignant and unspecified'. Treatment-emergent neoplasms judged to be malignant were included in this analysis. The database included 31 studies, 12 in type 1 diabetes and 19 in type 2 diabetes. Twenty compared insulin glargine with NPH insulin, 29 were parallel-group studies and two had a crossover design. Studies were generally of 6 months' duration, except for trial reference number 4016 (n = 1,017), which had a duration of 5 years. Overall, 10,880 people were included in the analysis (insulin glargine, 5,657; comparator, 5,223). Forty-five people (0.8%) vs 46 people (0.9%) reported 52 and 48 cases of malignant cancer in the insulin glargine and comparator groups, respectively (RR 0.90, 95% CI 0.60-1.36). Skin (12 people with 16 events vs six people with seven events, RR 1.85, 95% CI 0.69-4.92), colon and rectum (six vs ten people, RR 0.55, 95% CI 0.20-1.52), breast (four vs six people, RR 0.62, 95% CI 0.17-2.18) and gastrointestinal tract (six vs four people, RR 1.38, 95% CI 0.39-4.90) were the most commonly reported sites. In these 31 RCTs, insulin glargine was not associated with an increased incidence of cancer, including breast cancer, compared with the comparator group.