Fatty liver and transaminase changes with adjuvant tamoxifen therapy

We investigated the time it took to develop fatty liver and changes in serum aspartate aminotransferase and alanine aminotransferase levels in patients with breast cancer treated with adjuvant tamoxifen. Liver sonography to detect fatty liver and measurement of serum aspartate and alanine aminotransferase levels were performed regularly for patients with early breast cancer. The results were compared in groups of patients with and without adjuvant tamoxifen as well as those on chemotherapy. Eighty-two of 156 patients treated with tamoxifen developed fatty liver, compared with eight of 62 patients not taking it. Fatty liver appeared as early as 3 months after beginning tamoxifen and was detected within 2 years in most cases. It persisted for 48 months after discontinuing tamoxifen in 17 of the 82 patients who developed it. The incidence of fatty liver in patients receiving both chemotherapy and tamoxifen was the same as that in patients receiving tamoxifen alone. While 115 patients had elevations of aspartate aminotransferase, alanine aminotransferase or both, the magnitude of the elevation was clinically significant in only 32 patients. Patients on both chemotherapy and tamoxifen had a higher incidence of elevated transaminases than those on tamoxifen alone. Adjuvant tamoxifen increases the incidence of fatty liver, but has only a minimal effect on aspartate aminotransferase and alanine aminotransferase. Fatty liver may appear as early as 3 months after beginning tamoxifen and may persist for more than 4 years after discontinuing it. Therefore, long-term follow-up is warranted. Chemotherapy is not clearly associated with fatty liver, but may cause a greater degree of hepatocellular damage than does tamoxifen.