To analyze the contribution of lymphocytes to the effectiveness of cetuximab during CRC treatment, we assessed the peripheral blood lymphocyte subsets of cetuximab‐treated patients with CRC longitudinally using flow cytometry, which was intended to probe NK cells (CD3−CD56+), NKT cells (CD3+ CD56+), and T cells. Here, NCAM1 is linked to colorectal carcinoma.