# Drug-Induced Liver Injury Secondary to Endocrine Therapy With Aromatase Inhibitors: A Case Report

## TL;DR

A 76-year-old woman developed liver injury from anastrozole, an aromatase inhibitor used for breast cancer, highlighting the rare but serious risk of drug-induced liver injury.

## Contribution

This case report adds to the clinical understanding of drug-induced liver injury caused by aromatase inhibitors in breast cancer treatment.

## Key findings

- Anastrozole caused abnormal liver function tests in a postmenopausal woman with breast cancer.
- Liver enzymes normalized after discontinuing anastrozole for two months.
- The patient opted for observation instead of alternative endocrine therapy after the injury.

## Abstract

Aromatase inhibitors (AIs) are routinely used in treating estrogen receptor (ER)-positive breast cancer in postmenopausal women and are effective in reducing the recurrence of metastatic hormone-sensitive breast cancer. We present the case of a 76-year-old female with a past medical history of hypothyroidism and dyslipidemia who presented for the treatment of ER-positive pleomorphic lobular carcinoma in situ (LCIS). After initiating anastrozole, she developed weakness, loss of appetite, darkening of urine, and jaundice. Upon admission to the hospital, results from the patient’s initial workup revealed abnormal liver function tests. Anastrozole was identified as the causative agent for hepatic injury and was discontinued. The patient’s liver enzymes normalized two months off of the medication, and she decided to proceed with routine observation rather than initiating new endocrine therapy. This case emphasizes the importance of recognizing drug-induced liver injury (DILI) as a rare and serious complication of anastrozole use and highlights the need for consideration of possible risks with endocrine therapies.