CST3 and ocular cancer: For example, ELISA analysis of cystatin C and lactoferrin in serum, tear fluid, and intraocular fluid samples of choroidal melanoma and benign eye tumors found that (i) for healthy controls, cystatin C concentration was significantly higher in serum than in tear and intraocular fluids; (ii) for choroidal melanoma patients, cystatin C concentration was similarly increased in tear fluids of both eyes; (iii) for healthy controls, lactoferrin was significantly higher in tears than in serum; and (iv) for benign and malignant eye tumors, lactoferrin was significantly elevated in tears [154].