Background: Reproductive and menstrual factors have been evaluated as surrogates for long-term hormonal exposures in several prospective studies of colorectal cancer, yet findings have been conflicting. Methods: The relation of reproductive and menstrual factors (self-reported via a reproductive history questionnaire) with incident colorectal cancer was investigated among women enrolled in the Women's Health Initiative Observational Study (WHI-OS), a longitudinal cohort of 93 676 postmenopausal women (aged 50-79 years at enrolment) in which 1149 incident cases of colorectal cancer occurred over a median follow-up of 11.9 years. Multivariable Cox proportional hazards models that included established colorectal cancer risk factors were constructed to examine the association of colorectal cancer incidence with reproductive and menstrual factors. Results: Having had two children (vs nulliparous: hazard ratio (HR) = 0.80, 95% confidence interval (CD: 0.64-0.99) was inversely associated with colorectal cancer risk. Compared with never users, ever use of oral contraceptives was associated with lower colorectal cancer risk (HR = 0.74, 95% CI: 0.63-0.86); however, no relationship was observed for duration of oral contraceptives use (4 years vs 1 year: HR = 0.94, 95% CI: 0.67-1.32). None of the remaining reproductive and menstrual factors was associated with colorectal cancer incidence. Conclusions: Parity and prior use of oral contraceptives were associated with lower colorectal cancer risk in this cohort of postmenopausal women.
| Identifer | oai:union.ndltd.org:arizona.edu/oai:arizona.openrepository.com:10150/623103 |
| Date | 29 November 2016 |
| Creators | Murphy, Neil, Xu, Linzhi, Zervoudakis, Alice, Xue, Xiaonan, Kabat, Geoffrey, Rohan, Thomas E, Wassertheil-Smoller, Sylvia, O’Sullivan, Mary Jo, Thomson, Cynthia, Messina, Catherine, Strickler, Howard D, Gunter, Marc J |
| Contributors | Univ Arizona, Mel & Enid Zuckerman Coll Publ Hlth, Canyon Ranch Ctr Prevent & Hlth Promot |
| Publisher | NATURE PUBLISHING GROUP |
| Source Sets | University of Arizona |
| Language | English |
| Detected Language | English |
| Type | Article |
| Rights | © 2017 Cancer Research UK. All rights reserved 0007 – 0920/17 |
| Relation | http://www.nature.com/doifinder/10.1038/bjc.2016.345 |
Page generated in 0.0023 seconds