GGT1 and renal cell carcinoma: It is worth noting that the results of the six studies of RCC were often contradictory; one study enrolling a relatively small patient cohort with heterogeneous clinicopathological demographics (n = 80) showed that elevated serum GGT was observed only in patients with RCC with non-bone metastases but did not predict the survival of the patients [7] while another study enrolling 700 patients with non-metastatic RCC revealed that serum GGT predicted metastasis-free survival but not overall survival or cancer-specific survival [9].