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Hormone replacement therapy in relation to breast carcinoma incidence rate ratios: a prospective Danish cohort study.
Cancer. 2004 Jun 01; 100(11):2328-37.C

Abstract

BACKGROUND

The goal of the current study was to investigate the relation between hormone replacement therapy (HRT) and breast carcinoma in a prospective study cohort. Particular attention was paid to the type of HRT used and to the association of HRT type with estrogen receptor status and tumor histology.

METHODS

Between 1993 and 1997, a total of 29,875 women were enrolled in the Danish Cancer Society's prospective "Diet, Cancer and Health" study. Among 23,618 women who were assumed to be postmenopausal and for whom information on HRT use was available, we identified 423 cases of breast carcinoma over a median follow-up period of 4.8 years. Statistical analyses were based on the Cox proportional hazards model, with age serving as the time parameter.

RESULTS

The breast carcinoma incidence rate ratio (IRR) was 2.22 (95% confidence interval [CI], 1.80-2.75) for users of HRT at baseline compared with women who never received HRT. Among HRT users (relative to nonusers), the IRR for estrogen receptor-positive tumors (2.38; 95% CI, 1.84-3.06) was greater than the IRR for estrogen receptor-negative tumors (1.56; 95% CI, 1.00-2.43). HRT use at baseline also was analyzed in relation to the incidence of lobular carcinoma and the incidence of ductal carcinoma; the adjusted IRR associated with HRT use was 3.53 (95% CI, 1.94-6.41) for lobular carcinoma and 2.10 (95% CI, 1.64-2.70) for ductal carcinoma. The likelihood of developing estrogen receptor-positive breast carcinoma was found to depend significantly on the type of HRT regimen used (P = 0.03), with women receiving continuous therapy having the greatest probability of developing estrogen receptor-positive disease.

CONCLUSIONS

An increased breast carcinoma IRR was found to be associated with current HRT use. In addition, relative to other types of HRT regimens, continuous estrogen + progestin regimens were found to be associated with an increased risk of breast carcinoma, and particularly estrogen receptor-positive breast carcinoma.

Authors+Show Affiliations

Institute of Cancer Epidemiology, Danish Cancer Society, Copenhagen, Denmark. annet@cancer.dkNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

15160335

Citation

Tjønneland, Anne, et al. "Hormone Replacement Therapy in Relation to Breast Carcinoma Incidence Rate Ratios: a Prospective Danish Cohort Study." Cancer, vol. 100, no. 11, 2004, pp. 2328-37.
Tjønneland A, Christensen J, Thomsen BL, et al. Hormone replacement therapy in relation to breast carcinoma incidence rate ratios: a prospective Danish cohort study. Cancer. 2004;100(11):2328-37.
Tjønneland, A., Christensen, J., Thomsen, B. L., Olsen, A., Overvad, K., Ewertz, M., & Mellemkjaer, L. (2004). Hormone replacement therapy in relation to breast carcinoma incidence rate ratios: a prospective Danish cohort study. Cancer, 100(11), 2328-37.
Tjønneland A, et al. Hormone Replacement Therapy in Relation to Breast Carcinoma Incidence Rate Ratios: a Prospective Danish Cohort Study. Cancer. 2004 Jun 1;100(11):2328-37. PubMed PMID: 15160335.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Hormone replacement therapy in relation to breast carcinoma incidence rate ratios: a prospective Danish cohort study. AU - Tjønneland,Anne, AU - Christensen,Jane, AU - Thomsen,Birthe L, AU - Olsen,Anja, AU - Overvad,Kim, AU - Ewertz,Marianne, AU - Mellemkjaer,Lene, PY - 2004/5/26/pubmed PY - 2004/7/21/medline PY - 2004/5/26/entrez SP - 2328 EP - 37 JF - Cancer JO - Cancer VL - 100 IS - 11 N2 - BACKGROUND: The goal of the current study was to investigate the relation between hormone replacement therapy (HRT) and breast carcinoma in a prospective study cohort. Particular attention was paid to the type of HRT used and to the association of HRT type with estrogen receptor status and tumor histology. METHODS: Between 1993 and 1997, a total of 29,875 women were enrolled in the Danish Cancer Society's prospective "Diet, Cancer and Health" study. Among 23,618 women who were assumed to be postmenopausal and for whom information on HRT use was available, we identified 423 cases of breast carcinoma over a median follow-up period of 4.8 years. Statistical analyses were based on the Cox proportional hazards model, with age serving as the time parameter. RESULTS: The breast carcinoma incidence rate ratio (IRR) was 2.22 (95% confidence interval [CI], 1.80-2.75) for users of HRT at baseline compared with women who never received HRT. Among HRT users (relative to nonusers), the IRR for estrogen receptor-positive tumors (2.38; 95% CI, 1.84-3.06) was greater than the IRR for estrogen receptor-negative tumors (1.56; 95% CI, 1.00-2.43). HRT use at baseline also was analyzed in relation to the incidence of lobular carcinoma and the incidence of ductal carcinoma; the adjusted IRR associated with HRT use was 3.53 (95% CI, 1.94-6.41) for lobular carcinoma and 2.10 (95% CI, 1.64-2.70) for ductal carcinoma. The likelihood of developing estrogen receptor-positive breast carcinoma was found to depend significantly on the type of HRT regimen used (P = 0.03), with women receiving continuous therapy having the greatest probability of developing estrogen receptor-positive disease. CONCLUSIONS: An increased breast carcinoma IRR was found to be associated with current HRT use. In addition, relative to other types of HRT regimens, continuous estrogen + progestin regimens were found to be associated with an increased risk of breast carcinoma, and particularly estrogen receptor-positive breast carcinoma. SN - 0008-543X UR - https://www.unboundmedicine.com/medline/citation/15160335/Hormone_replacement_therapy_in_relation_to_breast_carcinoma_incidence_rate_ratios:_a_prospective_Danish_cohort_study_ L2 - https://doi.org/10.1002/cncr.20250 DB - PRIME DP - Unbound Medicine ER -