title: Tamoxifen's protection against breast cancer recurrence is not reduced by concurrent use of the SSRI citalopram.
abstract: Tamoxifen remains an important adjuvant therapy to reduce the rate of breast cancer recurrence among patients with oestrogen-receptor-positive tumours. Cytochrome P-450 2D6 metabolizes tamoxifen to metabolites that more readily bind the oestrogen receptor. This enzyme also metabolizes selective serotonin reuptake inhibitors (SSRI), so these widely used drugs - when taken concurrently - may reduce tamoxifen's prevention of breast cancer recurrence. We studied citalopram use in 184 cases of breast cancer recurrence and 184 matched controls without recurrence after equivalent follow-up. Cases and controls were nested in a population of female residents of Northern Denmark with stages I-III oestrogen-receptor-positive breast cancer 1985-2001 and who took tamoxifen for 1, 2, or most often for 5 years. We ascertained prescription histories by linking participants' central personal registry numbers to prescription databases from the National Health Service. Seventeen cases (9%) and 21 controls (11%) received at least one prescription for the SSRI citalopram while taking tamoxifen (adjusted conditional odds ratio=0.85, 95% confidence interval=0.42, 1.7). We also observed no reduction of tamoxifen effectiveness among regular citalopram users (>or=30% overlap with tamoxifen use). These results suggest that concurrent use of citalopram does not reduce tamoxifen's prevention of breast cancer recurrence.
authors.affiliation: Department of Epidemiology, Boston University School of Public Health, 715 Albany Street, Boston, MA 02118, USA. tlash@bu.edu
authors.forename: T L
authors.initials: TL
authors.lastname: Lash
authors.forename: L
authors.initials: L
authors.lastname: Pedersen
authors.forename: D
authors.initials: D
authors.lastname: Cronin-Fenton
authors.forename: T P
authors.initials: TP
authors.lastname: Ahern
authors.forename: C L
authors.initials: CL
authors.lastname: Rosenberg
authors.forename: K L
authors.initials: KL
authors.lastname: Lunetta
authors.forename: R A
authors.initials: RA
authors.lastname: Silliman
authors.forename: S
authors.initials: S
authors.lastname: Hamilton-Dutoit
authors.forename: J P
authors.initials: JP
authors.lastname: Garne
authors.forename: M
authors.initials: M
authors.lastname: Ewertz
authors.forename: H T
authors.initials: HT
authors.lastname: Sørensen
mesh_terms: D000328:Adult; D000368:Aged; D018931:Antineoplastic Agents, Hormonal / Q000627:therapeutic use*; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000532:radiotherapy / Q000601:surgery; D016022:Case-Control Studies; D015283:Citalopram / Q000627:therapeutic use*; D004359:Drug Therapy, Combination; D005260:Female; D006801:Humans; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000175:diagnosis / Q000517:prevention & control*; D009367:Neoplasm Staging; D017367:Selective Serotonin Reuptake Inhibitors / Q000627:therapeutic use*; D015996:Survival Rate; D013629:Tamoxifen / Q000627:therapeutic use*; D016896:Treatment Outcome
chemical_list: D018931:Antineoplastic Agents, Hormonal; D015283:Citalopram; D017367:Selective Serotonin Reuptake Inhibitors; D013629:Tamoxifen