title: The influence of hormone therapies on colon and rectal cancer.
abstract: Exogenous sex hormones seem to play a role in colorectal carcinogenesis. Little is known about the influence of different types or durations of postmenopausal hormone therapy (HT) on colorectal cancer risk. A nationwide cohort of women 50-79 years old without previous cancer (n = 1,006,219) were followed 1995-2009. Information on HT exposures was from the National Prescription Register and updated daily, while information on colon (n = 8377) and rectal cancers (n = 4742) were from the National Cancer Registry. Potential confounders were obtained from other national registers. Poisson regression analyses with 5-year age bands included hormone exposures as time-dependent covariates. Use of estrogen-only therapy and combined therapy were associated with decreased risks of colon cancer (adjusted incidence rate ratio 0.77, 95 % confidence interval 0.68-0.86 and 0.88, 0.80-0.96) and rectal cancer (0.83, 0.72-0.96 and 0.89, 0.80-1.00), compared to never users. Transdermal estrogen-only therapy implied more protection than oral administration, while no significant influence was found of regimen, progestin type, nor of tibolone. The benefit of HT was stronger for long-term hormone users; and hormone users were at lower risk of advanced stage of colorectal cancer, which seems supportive for a causal association between hormone therapy and colorectal cancer.
authors.affiliation: Gynecological Clinic, The Juliane Marie Centre, Copenhagen University Hospital, Blegdamsvej 9, 2100, Copenhagen, Denmark. linamorch@yahoo.dk.|Unit of Virus, Lifestyle and Genes, Danish Cancer Society Research Centre, Copenhagen, Denmark. linamorch@yahoo.dk.
authors.forename: Lina Steinrud
authors.initials: LS
authors.lastname: Mørch
authors.affiliation: Gynecological Clinic, The Juliane Marie Centre, Copenhagen University Hospital, Blegdamsvej 9, 2100, Copenhagen, Denmark.
authors.forename: Øjvind
authors.initials: Ø
authors.lastname: Lidegaard
authors.affiliation: Department of Biostatistics, Institute of Public Health, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Niels
authors.initials: N
authors.lastname: Keiding
authors.affiliation: Gynecological-Obstetrical Department, North Zealand Hospital, University of Copenhagen, Hillerød, Denmark.
authors.forename: Ellen
authors.initials: E
authors.lastname: Løkkegaard
authors.affiliation: Gynecological Clinic, The Juliane Marie Centre, Copenhagen University Hospital, Blegdamsvej 9, 2100, Copenhagen, Denmark.|Unit of Virus, Lifestyle and Genes, Danish Cancer Society Research Centre, Copenhagen, Denmark.
authors.forename: Susanne Krüger
authors.initials: SK
authors.lastname: Kjær
mesh_terms: D000368:Aged; D003110:Colonic Neoplasms / Q000139:chemically induced* / Q000453:epidemiology; D015179:Colorectal Neoplasms / Q000139:chemically induced / Q000453:epidemiology; D003718:Denmark / Q000453:epidemiology; D015914:Estrogen Replacement Therapy / Q000009:adverse effects*; D004967:Estrogens / Q000008:administration & dosage*; D005260:Female; D006801:Humans; D015994:Incidence; D008137:Longitudinal Studies; D008875:Middle Aged; D011159:Population Surveillance; D017698:Postmenopause; D012004:Rectal Neoplasms / Q000139:chemically induced* / Q000453:epidemiology; D012042:Registries; D018570:Risk Assessment
chemical_list: D004967:Estrogens
keywords: Colon cancer; Hormone replacement therapy; Rectum cancer; Stage of disease; Types of hormone therapy