Risk of breast cancer in risperidone users: A nationwide cohort study.
Several antipsychotics, especially risperidone, are known to increase serum prolactin. Hyperprolactinemia has been linked to the development of mammary gland tumors in animal studies. We therefore investigated the risk of breast cancer in a nationwide cohort of women using risperidone or other antipsychotics.



All women, 18years or older, who initiated treatment with risperidone or any other antipsychotic between 2006 and 2012 were identified in Swedish nationwide registers. Patients with two consecutive dispensations of the same antipsychotic within 3months, no previous cancer diagnosis, and no previous dispensations of paliperidone were included. The final cohort consisted of 55976 women of whom 22908, 24524, and 8544 were exposed to risperidone, other atypical antipsychotics, and typical antipsychotics, respectively. A Cox regression model was used to estimate the hazard ratio (HR) and 95% confidence interval (CI) for the association between antipsychotics and breast cancer.



Patients were followed prospectively, the mean follow-up time ranging from 2.4 to 2.8years between treatment groups. After adjusting for age, there was no increased risk for breast cancer among risperidone users compared to patients exposed to another atypical antipsychotic (HR 0.94, 95% CI 0.72-1.22) or a typical antipsychotic (HR 1.25, 95% CI 0.94-1.66). Analyses stratified by tumor stage, using active treatment follow-up time, or including only treatment naïve patients did not reveal any noteworthy change in the results.



Risperidone use does not confer an increased short-term risk of breast cancer compared to other antipsychotic agents.
Centre for Pharmacoepidemiology, Department of Medicine, Solna, Karolinska Institutet, Karolinska University Hospital, Stockholm, Sweden. Electronic address: johan.reutfors@ki.se.
Johan
J
Reutfors
Centre for Pharmacoepidemiology, Department of Medicine, Solna, Karolinska Institutet, Karolinska University Hospital, Stockholm, Sweden.
Louise
L
Wingård
Centre for Pharmacoepidemiology, Department of Medicine, Solna, Karolinska Institutet, Karolinska University Hospital, Stockholm, Sweden.
Lena
L
Brandt
Janssen Research and Development, Department of Epidemiology, Titusville, NJ, USA.
Yiting
Y
Wang
Janssen Research and Development, Department of Epidemiology, Titusville, NJ, USA.
Hong
H
Qiu
Centre for Pharmacoepidemiology, Department of Medicine, Solna, Karolinska Institutet, Karolinska University Hospital, Stockholm, Sweden.
Helle
H
Kieler
Centre for Pharmacoepidemiology, Department of Medicine, Solna, Karolinska Institutet, Karolinska University Hospital, Stockholm, Sweden.
Shahram
S
Bahmanyar
D000293:Adolescent; D000328:Adult; D017677:Age Distribution; D000368:Aged; D000369:Aged, 80 and over; D014150:Antipsychotic Agents / Q000009:adverse effects*; D001943:Breast Neoplasms / Q000139:chemically induced*; D015331:Cohort Studies; D005260:Female; D006801:Humans; D001523:Mental Disorders / Q000188:drug therapy*; D008875:Middle Aged; D012307:Risk Factors; D018967:Risperidone / Q000009:adverse effects*; D016896:Treatment Outcome; D055815:Young Adult
D014150:Antipsychotic Agents; D018967:Risperidone
Antipsychotics; Atypical antipsychotics; Breast cancer; Cohort study; Risperidone