The use of atypical antipsychotics and the risk of breast cancer (Q10-04)

The use of atypical antipsychotics and the risk of breast cancer (Q10-04)

Q10-04

Overview

What is the issue?
  • Antipsychotic drugs are typically used in the treatment of a number of psychiatric disorders, including schizophrenia and bipolar disease, but the off-label use of these drugs increased significantly even after regulatory warnings.
  • Antipsychotics block the effects of dopamine, and thus hyperprolactinemia is a common side effect. Long-term effects of hyperprolactinemia may include breast cancer.
  • Few studies investigated the association between antipsychotics and breast cancer.
What is the aim of the study?
  • We rapidly evaluated the use of atypical antipsychotics and the potential association with an increased risk of breast cancer, when compared to typical antipsychotics.
How was the study conducted?
  • We conducted an observational study, using a nested case-control design, within the the General Practice Research Database.
  • The cohort included female patients prescribed at least one antipsychotic prescription (either typical or atypical), between 1 January 1988 and 31 December 2007, with follow-up until 31 December 2010.
What did the study find?
  • Of the 106,362 patients prescribed antipsychotics, there were 1,237 diagnosed with incident breast cancer during the follow up period.
  • Users of atypical antipsychotics were not at an increased risk of breast cancer (rate ratio [RR]: 0.81, 95% CI: 0.63, 1.05), compared with those who only used typical antipsychotics.
  • Results were consistent after considering specific atypical antipsychotics known to significantly increase prolactin levels such as risperidone (RR: 0.86, 95% CI: 0.60, 1.25).
    Furthermore, no dose-response was observed in terms of cumulative duration of use and cumulative dose in olanzapine equivalents.

Implications
  • The results suggest that antipsychotics, either typical or atypical, are not associated with an increased risk of breast cancer.

Manuscripts

Presentations

Project Team

Project Co-Lead
Laurent Azoulay PhD
Coordinating Center
Project Co-Lead
Samy Suissa PhD
Coordinating Center
Site Investigator
Adrian Levy PhD
Atlantic
Site Investigator
Gary Teare DVM, MSc, PhD
Saskatchewan
Site Investigator
Brenda Hemmelgarn MD, PhD, FRCPC
Alberta
Site Investigator
Colin R. Dormuth ScD
British Columbia
Co-Site Investigator
Jacques LeLorier MD, MSc, FRCPC, FISPE
Quebec
Co-Site Investigator
Robert W. Platt PhD
Quebec
Co-Site Investigator
Michael Paterson MSc
Ontario
Co-Site Investigator
David Henry MBChB, MRCP, FRCP (Edin)
Ontario
Co-Site Investigator
Patricia Caetano PhD
Manitoba
Co-Site Investigator
Patricia Martens
Manitoba