Clinical significance of fatty liver disease induced by tamoxifen and toremifene in breast cancer patients

The aim of this study was to identify the effect of selective estrogen receptor modulator (SERM) on non-alcoholic fatty liver disease (NAFLD) in Asian women.We retrospectively evaluated fatty liver development and/or serum alanine aminotransferase (ALT) elevation during SERM treatment in 1061 women who were diagnosed and treated with breast cancer in 2005 at Asan Medical Center.45 of 618 SERM-treated patients with normal ALT at baseline experienced ALT elevation during SERM treatment. Among the 112 SERM-treated patients who underwent liver imaging test, fatty liver was observed in 47 and both fatty liver and ALT elevation developed in 16 of 102 SERM-treated patients with normal baseline ALT. The cumulative rates of ALT elevation (10.7 vs. 4.3%; P = 0.002), fatty liver (48.5 vs. 20.9%; P 0.001), and both fatty liver and ALT elevation (17.7 vs. 7.1%; P = 0.02) at 60 months were significantly higher in the SERM group than non-SERM group. By multivariate analysis, SERM treatment increased the risk of ALT elevation (hazard ratio [HR], 2.20; P = 0.01), fatty liver development (HR, 3.59; P 0.001), and both fatty liver and ALT elevation (HR, 4.98; P = 0.01). After discontinuation of SERM, elevated serum ALT normalized in 39 (92.9%) and there were no instances of liver-related death or progression to liver cirrhosis in patients who experienced fatty liver or ALT elevation.Although SERM treatment is significantly associated with NAFLD in Asian women, considering the tolerability and reversibility of NAFLD induced by SERM, it can be continued with liver function monitoring in relevant patients.