title: Reproductive and menstrual factors in relation to mammographic parenchymal patterns among perimenopausal women.
abstract: The relationship between mammographic patterns and reproductive and menstrual factors was examined in 3640 Norwegian women, aged 40-56 years, participating in the Third Tromsö study conducted in 1986-87. Epidemiological data were obtained from questionnaires. The mammograms were categorised into five groups. This categorisation is based on anatomic-mammographic correlations, following three-dimensional (thick slice technique) histopathologic-mammographic comparisons, rather than simple pattern reading. Patterns 1-3 were combined into a low-risk group and patterns 4 and 5 into a high-risk group for analysis. Women who had more than four children were 90% less likely to have a high-risk pattern than nulliparous women (OR = 0.09, 95% CI 0.04-0.16) controlling for age, weight, height and menopausal status. Furthermore, those who first gave birth over 34 years of age were more than twice as likely to have a high-risk pattern than those giving birth in their teens (OR = 2.37, 95% CI 1.23-4.56) adjusting for parity. Among post-menopausal women, age at menarche was negatively (P for trend = 0.015) and late age at menopause positively (P for trend = 0.072) related to high-risk patterns. Among premenopausal women, age at menarche was positively related to high-risk patterns (P for trend = 0.001). Also, menopausal status rather than age was associated with high-risk patterns. These findings support the opinion that reproductive and menstrual factors are involved in determining the mammographic parenchymal pattern among perimenopausal women.
authors.affiliation: Institute of Community Medicine, University of Tromsö, Breivika, Norway.
authors.forename: I T
authors.initials: IT
authors.lastname: Gram
authors.forename: E
authors.initials: E
authors.lastname: Funkhouser
authors.forename: L
authors.initials: L
authors.lastname: Tabar
mesh_terms: D000328:Adult; D001943:Breast Neoplasms / Q000453:epidemiology / Q000209:etiology*; D005260:Female; D006801:Humans; D008327:Mammography; D008598:Menstruation; D008875:Middle Aged; D010298:Parity; D017697:Premenopause; D015995:Prevalence; D012098:Reproduction; D012307:Risk Factors