Increased risk for invasive breast cancer associated with hormonal therapy: a nation-wide random sample of 65,723 women followed from 1997 to 2008.

Abstract

BACKGROUND:

Hormonal therapy (HT) either estrogen alone (E-alone) or estrogen plus progesterone (E+P) appears to increase the risk for breast cancer in Western countries. However, limited information is available on the association between HT and breast cancer in Asian women characterized mainly by dietary phytoestrogens intake and low prevalence of contraceptive pills prescription.

METHODOLOGY:

A total of 65,723 women (20-79 years of age) without cancer or the use of Chinese herbal products were recruited from a nation-wide one-million representative sample of the National Health Insurance of Taiwan and followed from 1997 to 2008. Seven hundred and eighty incidents of invasive breast cancer were diagnosed. Using a reference group that comprised 40,052 women who had never received a hormone prescription, Cox proportional hazard models were constructed to determine the hazard ratios for receiving different types of HT and the occurrence of breast cancer.

CONCLUSIONS:

5,156 (20%) women ever used E+P, 2,798 (10.8%) ever used E-alone, and 17,717 (69%) ever used other preparation types. The Cox model revealed adjusted hazard ratios (HRs) of 2.05 (95% CI 1.37-3.07) for current users of E-alone and 8.65 (95% CI 5.45-13.70) for current users of E+P. Using women who had ceased to take hormonal medication for 6 years or more as the reference group, the adjusted HRs were significantly elevated and greater than current users and women who had discontinued hormonal medication for less than 6 years. Current users of either E-alone or E+P have an increased risk for invasive breast cancer in Taiwan, and precautions should be taken when such agents are prescribed.

• Authors: Jung-Nien Lai, Chien-Tung Wu, Pau-Chung Chen, Chiun-Sheng Huang, Song-Nan Chow, Jung-Der Wang
• Journal: PloS one (PLoS One) Vol. 6 Issue 10 Pg. e25183 ( 2011) ISSN: 1932-6203 [Electronic] United States
• PMID: 21998640 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Topics

• Adult
• Aged
• Breast Neoplasms (epidemiology, etiology, pathology)
• Cohort Studies
• Female
• Hormone Replacement Therapy (adverse effects)
• Humans
• Middle Aged
• Multivariate Analysis
• Neoplasm Invasiveness
• Proportional Hazards Models
• Retrospective Studies
• Risk
• Taiwan (epidemiology)
• Young Adult