CALCA and malignant colon neoplasm: Our findings of higher PCT levels in certain malignancies such as: colon cancer, leukemia, thyroid cancer, lymphoma, and prostate cancer agree with previous reports of increased serum PCT in tumors such as small cell lung cancer, carcinoid, pheochromocytoma, pancreatic islet, breast, thyroid, lung, gastro-intestinal including colon cancer and urogenital tumors [8, 9, 19, 20].