title: Oral contraceptives and the risk of all cancers combined and site-specific cancers in Shanghai.
abstract: From 1998 to 1991, an in-person baseline interview was administered to approximately 267,400 female textile workers in Shanghai, China. The cohort was followed until July 2000 for incident cancer cases. Incidence rate ratios (RR) for 12 types of cancers in users of oral contraceptives (OCs) were calculated using Cox Proportional Hazards analysis. There was a reduced risk of uterine corpus cancer for women who had ever used OCs (RR = 0.68, 95% CI = 0.45-1.04) and a trend of decreasing risk with increasing duration of use (p = 0.015). There was an increased risk of colon cancer in women who had used OCs for 10 years or more (RR = 1.56, 95% CI = 1.01-2.40) and an increased risk of rectal cancer in women who had ever used OCs (RR = 1.31, 95% CI = 0.98-1.75), with a trend of increasing risk with increasing duration of use (p = 0.017), but these associations may have been due to uncontrolled confounding by physical activity or other non-causal factors. No associations were observed between OCs and the risk of all cancers combined or for any of the nine other cancers. It is unlikely that the use of OCs has contributed to the temporal trends in cancer incidence in China in recent decades.
authors.affiliation: Department of Kinesiology and Community Health, University of Illinois at Urbana Champaign, 127 Huff Hall, 1206 S. Fourth St., Champaign, IL 61820, USA. krosenbl@uiuc.edu
authors.forename: Karin A
authors.initials: KA
authors.lastname: Rosenblatt
authors.forename: Dao L
authors.initials: DL
authors.lastname: Gao
authors.forename: Roberta M
authors.initials: RM
authors.lastname: Ray
authors.forename: Zakia C
authors.initials: ZC
authors.lastname: Nelson
authors.forename: Karen J
authors.initials: KJ
authors.lastname: Wernli
authors.forename: Wenjin
authors.initials: W
authors.lastname: Li
authors.forename: David B
authors.initials: DB
authors.lastname: Thomas
mesh_terms: D002681:China; D015331:Cohort Studies; D003276:Contraceptives, Oral / Q000009:adverse effects*; D005260:Female; D006801:Humans; D009369:Neoplasms / Q000139:chemically induced / Q000453:epidemiology*; D018570:Risk Assessment
chemical_list: D003276:Contraceptives, Oral