By using CK20+/CD45-/DAPI+ as selection criteria and ≥2 CTCs per 2 mL blood as a cutoff, our platform obtained 70% of sensitivity, 89% of specificity, and 96% of positive prediction rate for the metastatic stage III-IV CRC patients from healthy donors except one out of 9 healthy donors has CTC count to two. The gene discussed is KRT20; the disease is colorectal carcinoma.