TAC1 and colorectal cancer: Our study aimed to correlate the serum levels of the neuropeptides substance P and calcitonin gene-related peptide and the immunohistochemical analysis of their receptors NK1R and CRLR with different patients’ characteristics and with the different tumor characteristics in patients with colorectal cancer and to compare their levels to see whether they could be used as biomarkers in diagnostics and prognosis and also the possibility of using them as future therapeutic targets in this pathology.