The seroreactivity of random plasma samples from four controls and eight CRC patients at different stages against two p53 and two p63 differential seroreactive isoforms (Δ133p53γ, Δ160p53γ, TAp63δ and ΔNp63α) was analyzed as a proof of concept to establish a biosensing platform able simultaneously to measure different proteoforms for CRC detection. The gene discussed is TP53; the disease is colorectal carcinoma.