title: Association between reproductive factors and breast cancer survival in younger women.
abstract: This analysis investigated whether reproductive factors such as age at menarche, parity, and timing and outcomes of pregnancies were associated with survival among women with breast cancer younger than 55 years. Female residents of Atlanta, Georgia, and central New Jersey who were diagnosed with a primary, incident invasive breast cancer between 1990 and 1992 and enrolled in a population-based study (n = 1,264) were followed for 8-10 years. Detailed exposure and covariate information was collected via in-person interviews administered shortly after diagnosis. Vital status as of January 1, 2000 was ascertained through the National Death Index via the state cancer registries (n = 292 deaths). Cox regression methods were used to estimate hazard ratios (HR) and 95% confidence intervals (CI) adjusted for confounders. Parity of 4 or more births, as compared with nulliparity, was positively associated with all-cause mortality, [HR (95% CI) = 1.71 (1.09-2.67)]. Increased mortality was associated with having given birth within 5 years prior to diagnosis (<or=5 vs. >5 years) [1.78 (1.28-2.47)], and was more pronounced among women with a pre-diagnostic body mass index of <25 kg/m2 [2.54 (1.61-4.00)]. Early age at menarche and early age at first birth also modestly increased mortality; history of miscarriage, induced abortion, and ever breastfeeding were not related to survival. These results may help elucidate breast cancer progression mechanisms and enable a better understanding of how reproductive characteristics influence breast cancer survival.
authors.affiliation: Department of Epidemiology, University of North Carolina at Chapel Hill, CB #7435, Chapel Hill, NC 27599-7435, USA. trivers@unc.edu
authors.forename: Katrina F
authors.initials: KF
authors.lastname: Trivers
authors.forename: Marilie D
authors.initials: MD
authors.lastname: Gammon
authors.forename: Page E
authors.initials: PE
authors.lastname: Abrahamson
authors.forename: Mary Jo
authors.initials: MJ
authors.lastname: Lund
authors.forename: Elaine W
authors.initials: EW
authors.lastname: Flagg
authors.forename: Jay S
authors.initials: JS
authors.lastname: Kaufman
authors.forename: Patricia G
authors.initials: PG
authors.lastname: Moorman
authors.forename: Jianwen
authors.initials: J
authors.lastname: Cai
authors.forename: Andrew F
authors.initials: AF
authors.lastname: Olshan
authors.forename: Peggy L
authors.initials: PL
authors.lastname: Porter
authors.forename: Louise A
authors.initials: LA
authors.lastname: Brinton
authors.forename: J William
authors.initials: JW
authors.lastname: Eley
authors.forename: Ralph J
authors.initials: RJ
authors.lastname: Coates
mesh_terms: D000328:Adult; D001943:Breast Neoplasms / Q000401:mortality*; D016022:Case-Control Studies; D005260:Female; D005845:Georgia / Q000453:epidemiology; D006801:Humans; D053208:Kaplan-Meier Estimate; D008875:Middle Aged; D015999:Multivariate Analysis; D009515:New Jersey / Q000453:epidemiology; D016016:Proportional Hazards Models; D017584:Reproductive History; D015996:Survival Rate