Epidemiology

BJC Open article

British Journal of Cancer (2014) 111, 1836–1842. doi:10.1038/bjc.2014.488 www.bjcancer.com
Published online 16 September 2014

Association of tamoxifen use and increased diabetes among Asian women diagnosed with breast cancer

L-M Sun1,8, H-J Chen2, J-A Liang3,4,8, T-C Li5,6 and C-H Kao4,7

  1. 1Department of Radiation Oncology, Zuoying Branch of Kaohsiung Armed Forces General Hospital, Kaohsiung, Taiwan
  2. 2Management Office for Health Data, China Medical University Hospital, Taichung, Taiwan
  3. 3Department of Radiation Oncology, China Medical University Hospital, Taichung, Taiwan
  4. 4Graduate Institute of Clinical Medical Science and School of Medicine, College of Medicine, China Medical University, Taichung, Taiwan
  5. 5Graduate Institute of Biostatistics, College of Management, China Medical University, Taichung, Taiwan
  6. 6Department of Healthcare Administration, College of Health Science, Asia University, Taichung, Taiwan
  7. 7Department of Nuclear Medicine and PET Center, China Medical University Hospital, Taichung, Taiwan

Correspondence: Professor C-H Kao, E-mail: d10040@mail.cmuh.org.tw

8These authors contributed equally to this work.

Received 8 May 2014; Revised 18 July 2014; Accepted 7 August 2014
Advance online publication 16 September 2014

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Abstract

Background:

  

We conducted a population-based cohort study to assess whether tamoxifen treatment is associated with an increased incidence of diabetes.

Methods:

  

Data obtained from the Taiwanese National Health Insurance Research Database were used for a population-based cohort study. The study cohort included 22257 breast cancer patients diagnosed between 1 January 2000 and 31 December 2004. Among them, 15210 cases received tamoxifen treatment and 7047 did not. Four subjects without breast cancer were frequency-matched by age and index year as the control group. Hazard ratios (HRs) and 95% confidence intervals (CIs) were estimated using multivariate Cox proportional hazards regression analysis.

Results:

  

Breast cancer patients exhibited a 14% higher rate of developing diabetes (adjusted HR=1.14, 95% CI=1.08–1.20) compared with non-breast cancer controls, but the significant difference was limited to tamoxifen users. In addition, tamoxifen users exhibited a significantly increased risk of diabetes compared with non-tamoxifen users among women diagnosed with breast cancer (adjusted HR=1.31, 95% CI=1.19–1.45). Stratification by age groups indicated that both younger and older women diagnosed with breast cancer exhibited a significantly higher risk of diabetes than the normal control subjects did, and tamoxifen users consistently exhibited a significantly higher diabetes risk than non-tamoxifen users or normal control subjects did, regardless of age. Both recent and remote uses of tamoxifen were associated with an increased likelihood of diabetes.

Conclusions:

  

The results of this population-based cohort study suggested that tamoxifen use in breast cancer patients might increase subsequent diabetes risk. The underlying mechanism remains unclear and further larger studies are mandatory to validate our findings.

Keywords:

tamoxifen; breast cancer; diabetes; population-based; cohort study