GLP-1 agonists and the risk of breast cancer in patients with type 2 diabetes

Date of Approval
Application Number
Technical Summary

Recent evidence from preclinical studies and randomised controlled trials suggest that GLP-1 agonists may increase the risk of breast cancer. However, to date, no observational study has investigated this potential safety issue. Thus, the objective of this study will be to assess this association by assembling a cohort of female patients who initiated a new antidiabetic drug class on or after January 1, 2007 until March 31, 2015. All patients will be followed until a first-ever diagnosis of breast cancer, or censored upon death, end of registration with the practice, or end of the study period (March 31, 2016). Time-dependent Cox proportional hazard models will be used to estimate hazard ratios and 95% confidence intervals of breast cancer associated with the use GLP-1 agonists when compared with the use of DPP-4 inhibitors, with exposures lagged by 1 year for latency purposes. Secondary analyses will assess whether the risk varies according to cumulative duration of use and time since initiation. This study will provide the concerned stakeholders with the necessary information to assess the risks and benefits of these therapies.

Health Outcomes to be Measured

Primary diagnosis of breast cancer (malignant and carcinoma in situ)


Samy Suissa - Chief Investigator - McGill University
Samy Suissa - Corresponding Applicant - McGill University
Blánaid Hicks - Collaborator - Queen's University Belfast
Hui Yin - Collaborator - Sir Mortimer B Davis Jewish General Hospital
Laurent Azoulay - Collaborator - McGill University
Michael Pollak - Collaborator - Sir Mortimer B Davis Jewish General Hospital
Oriana Hoi Yun Yu - Collaborator - Sir Mortimer B Davis Jewish General Hospital
Robert Platt - Collaborator - McGill University
Robert Platt - Collaborator - McGill University