Association between tamoxifen treatment and the development of different stages of nonalcoholic fatty liver disease among breast cancer patients

Background/Purpose: For estrogen-receptor positive breast cancer cases, tamoxifen has been the most important adjuvant hormonal therapy for the purpose of reducing recurrence rates and prolonging disease free survival. However, several side effects have been noticed, and fatty liver is one of the most common side effects among them. Since fatty liver is a common problem in the general population, we wanted to examine the effects of tamoxifen under pre-existing fatty liver conditions and evaluate the prevalence of tamoxifen-related impaired liver function. Methods: We recruited breast cancer cases at ages 20-70 years and divided them into tamoxifen or control groups. Personal information was collected, and fasting blood tests and abdominal ultrasound were performed. The changes of fatty liver degree between the initial and follow-up ultrasound were divided into five categories. Results: Of the 406 enrolled participants, 266 were in the tamoxifen group and 140 were in the control group. The tamoxifen group had a higher risk of newly developed fatty liver [hazard ratio (HR) = 3.69; 95% confidence interval (CI) 1.67-8.13), lower rate of improved fatty liver (HR = 0.33; 95% CI 0.15-0.75), and higher rate of worsened fatty liver (HR = 2.11; 95% CI 1.02-4.35). Conclusion: The current study suggests that tamoxifen treatment is associated with the risk of fatty liver either by increasing the risk of newly developed fatty liver conditions or worsening previous fatty liver conditions, and even retarding fatty liver improvement. Copyright (C) 2015, Formosan Medical Association. Published by Elsevier Taiwan LLC.