Therefore, this study aims to explore the expression profiling of the tumour suppressor genes p53 and APC (adenomatous polyposis coli), the oncogenes KRAS and c-Myc and selected immune checkpoints (PD-L1, CTLA-4 (cytotoxic T-lymphocyte-associated protein 4, CD152) and CD47 in CTCs and peripheral blood mononuclear cells (PBMCs) isolated from patients with CRC. The gene discussed is APC; the disease is colorectal carcinoma.