Accelerated Onset of Liver Failure after Prolonged Adjuvant Tamoxifen Use in Breast Cancer Patients

Use of adjuvant endocrine therapy for women with hormone-receptor (HR)-positive breast cancer has become the standard of care. Tamoxifen, an orally available selective estrogen receptor modulator (SERM), is a commonly used endocrine therapy agent currently recommended for use in pre- or post-menopausal women with HR-positive breast cancer. Current evidence suggests that prolonged tamoxifen use may be implicated in causing hepatotoxicity which may manifest as non-alcoholic steatohepatitis (NASH), cholestasis, cirrhosis, or hepatic necrosis. We herein present two cases of suspected tamoxifen-induced NASH resulting in fulminant liver failure. We also discuss literature surrounding tamoxifen-related hepatoxicity and implications in clinical practice.