GSTM1 and neoplasm: This study aimed to compare the diagnostic accuracy of different fecal markers in the detection of colorectal adenomas and cancer. Methods. Stool samples of patients referred to colonoscopy were collected for the analysis of tumor M2 pyruvate kinase (M2PK), human hemoglobin (Hb), hemoglobin/haptoglobin (Hb/Hp) complex, fecal calprotectin (FC), and matrix metalloproteinase-9 (MMP-9). Results. Sensitivity and specificity of M2PK for adenomas sized > 1 cm were 60% and 67.5% and for CRC were 94.7% and 67.5%.