GGT1 and pachyonychia congenita: Among these studies, a large prospective study in Sweden enrolling 545,460 patients demonstrated that elevated serum GGT was linked to an increased overall cancer risk in both men and women, and that patients with a diagnosis of PC with elevated serum GGT had an increased risk of a secondary diagnosis of a primary tumor, suggesting the possibility of shared aspects of GGT-related metabolism in PC and other later malignancies [76,77].