title: Breast cancer survival and the timing of tumor removal during the menstrual cycle.
abstract: In a retrospective cohort study of 262 premenopausal breast cancer patients treated at the Mayo Clinic between 1965 and 1985, we investigated whether survival was associated with the timing of tumor removal during the menstrual cycle. Participants were women < or = 50 years old who had not used exogenous hormones, been pregnant, been lactating, or given birth within 6 months of diagnosis. The menstrual cycle day at surgery was used to assign women to group 1 (cycle days 0-7), group 2 (cycle days 8-15), or group 3 (after cycle day 15). Cox proportional hazards analysis adjusting for age at diagnosis, stage, tumor size, grade, and node involvement showed a nonsignificantly worse survival for group 2 than for group 3 [hazard ratio (HR), 1.41; 95% confidence interval (CI), 0.89-2.23]. Stratification revealed that the association between survival and timing of tumor removal during the menstrual cycle was slightly stronger among patients with stage II disease (adjusted HR, 1.56; 95% CI, 0.92-2.63). The association was the same among patients with stage II disease and node involvement (adjusted HR, 1.57; 95% CI, 0.82-3.03). Prospective studies using hormone measurements to define menstrual cycle status more accurately than the reported day of the menstrual cycle could provide further insight about the postulated association.
authors.affiliation: Department of Epidemiology, University of North Carolina at Chapel Hill 27599-7400, USA. schang@notes.mdacc.tmc.edu
authors.forename: S
authors.initials: S
authors.lastname: Chang
authors.forename: B S
authors.initials: BS
authors.lastname: Hulka
authors.forename: D D
authors.initials: DD
authors.lastname: Baird
authors.forename: J N
authors.initials: JN
authors.lastname: Ingle
authors.forename: B
authors.initials: B
authors.lastname: Newman
authors.forename: M L
authors.initials: ML
authors.lastname: Graham
authors.forename: B
authors.initials: B
authors.lastname: Qaqish
authors.forename: J H
authors.initials: JH
authors.lastname: Donohue
authors.forename: L J
authors.initials: LJ
authors.lastname: Melton
mesh_terms: D000328:Adult; D001943:Breast Neoplasms / Q000401:mortality* / Q000473:pathology / Q000601:surgery*; D015331:Cohort Studies; D005260:Female; D006801:Humans; D008207:Lymphatic Metastasis; D008408:Mastectomy; D008597:Menstrual Cycle; D008875:Middle Aged; D015999:Multivariate Analysis; D009367:Neoplasm Staging; D017697:Premenopause; D016016:Proportional Hazards Models; D012189:Retrospective Studies; D016019:Survival Analysis