Gamma-glutamyl transpeptidase in the prognosis of patients with uveal malignant melanoma.

A study of 116 patients with histologically proven uveal malignant melanoma suggested that hepatic metastases were present at the same time that the ocular tumor was diagnosed in 15 patients (13%) by serum gamma-glutamyl transpeptidase assay. The average pretherapy gamma-glutamyl transpeptidase levels were statistically higher (P less than .01) in the 28 patients who developed metastases compared with those in 88 patients who have remained clinically free of metastases for a follow-up period of at least two years. The predictive value test indicated that pretherapy gamma-glutamyl transpeptidase levels greater than or equal to 22 IU/ml were increased in patients developing metastasis. With this upper-normal limit, 15 (54%) of the 28 patients who later developed clinical evidence of metastasis had increased pretherapy levels. In comparison, only 12 (14%) of the 88 patients who remained tumor-free for at least two years had increased pretherapy levels. Although not all patients who developed metastases had increased pretherapy levels, most developed increases at some time during the course of their disease. Because the gamma-glutamyl transpeptidase assay can detect hepatic metastases before other liver function assays, it should be included as a routine liver function study for patients with uveal malignant melanoma.