title: Grand multiparity and reproductive cancer in the Jerusalem Perinatal Study Cohort.
abstract: OBJECTIVE
  Grand multiparity is associated with reduced mortality from reproductive cancers. We aimed to separate the components of mortality, by measuring incidence of and survival after reproductive cancer onset in grand multiparous compared to other parous women.
  
  
  METHODS
  We linked data from the population-based Jerusalem Perinatal Study Cohort, which included women aged 13-55 who delivered 1964-1976, with Israel's National Cancer Registry. We compared breast and gynecologic cancer risk and all-cause survival following a cancer diagnosis, among grand multiparae (GMPs = parity 5+, n = 8,246) versus women with parity 1-4 (n = 19,703), adjusting for reproductive and demographic variables.
  
  
  RESULTS
  Grand multiparae were at significantly lower risk of breast cancer than others (adjusted hazard ratio (HRadj) = 0.62, 95 % confidence interval (CI) 0.54-0.71), after controlling for age at first birth, education, and other covariates. This reduction was greater among GMPs whose first birth occurred after age 30 (p-interaction = 0.0001) and for cancer occurring before age 50 years (p = 0.002). In contrast, GMPs were at greater risk of death than women with parity <5, following a breast cancer diagnosis (HRadj = 1.69, CI 1.39-2.1). Ovarian, uterine, and cervical cancer incidence did not differ between the groups, but survival was reduced for GMPs with uterine cancer (HRadj = 2.48, CI 1.22-5.03).
  
  
  CONCLUSIONS
  Reduced reproductive cancer mortality reported among GMPs masks two opposing phenomena: decreased breast cancer risk and poorer survival after breast and uterine cancers. The latter unfavorable outcome suggests that tumors in GMPs may be particularly aggressive, having perhaps escaped protective mechanisms conferred by parity. This finding calls for heightened clinical attention in this group.
authors.affiliation: Braun School of Public Health, Hadassah-Hebrew University, Jerusalem, Israel. orap@hadassah.org.il.|Department of Hematology, Hadassah-Hebrew University Medical Center, POB 12000, 91120, Jerusalem, Israel. orap@hadassah.org.il.
authors.forename: Ora
authors.initials: O
authors.lastname: Paltiel
authors.affiliation: Laboratory of Epidemiology and Population Sciences, National Institute on Aging, National Institutes of Health, Baltimore, MD, USA.
authors.forename: Salman M
authors.initials: SM
authors.lastname: Tajuddin
authors.affiliation: Braun School of Public Health, Hadassah-Hebrew University, Jerusalem, Israel.
authors.forename: Yelena
authors.initials: Y
authors.lastname: Polanker
authors.affiliation: Braun School of Public Health, Hadassah-Hebrew University, Jerusalem, Israel.
authors.forename: Shoshanah
authors.initials: S
authors.lastname: Yazdgerdi
authors.affiliation: Braun School of Public Health, Hadassah-Hebrew University, Jerusalem, Israel.
authors.forename: Orly
authors.initials: O
authors.lastname: Manor
authors.affiliation: Braun School of Public Health, Hadassah-Hebrew University, Jerusalem, Israel.
authors.forename: Yechiel
authors.initials: Y
authors.lastname: Friedlander
authors.affiliation: School of Medicine, New York University, New York, NY, USA.
authors.forename: Susan
authors.initials: S
authors.lastname: Harlap
authors.affiliation: Braun School of Public Health, Hadassah-Hebrew University, Jerusalem, Israel.
authors.forename: Ronit
authors.initials: R
authors.lastname: Calderon-Margalit
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D001943:Breast Neoplasms / Q000453:epidemiology* / Q000401:mortality; D015331:Cohort Studies; D005260:Female; D006801:Humans; D015994:Incidence; D007557:Israel / Q000453:epidemiology; D008423:Maternal Age; D008875:Middle Aged; D010051:Ovarian Neoplasms / Q000453:epidemiology* / Q000401:mortality; D010298:Parity; D011247:Pregnancy; D016016:Proportional Hazards Models; D017584:Reproductive History; D015996:Survival Rate; D002583:Uterine Cervical Neoplasms / Q000453:epidemiology* / Q000401:mortality; D014594:Uterine Neoplasms / Q000453:epidemiology* / Q000401:mortality; D055815:Young Adult
keywords: Breast cancer; Cohort study; Endometrial cancer; Multiparity; Survival