Our current work performed a multiplex PCR assay and high-throughput sequencing in CRC longitudinal cohorts to improve the understanding of the dynamic immune responses during cancer therapy and found that a decreased Chao1 index was correlated with declining CEA and CA19-9 biomarker levels instead of other parameters, including sex, age, and hematological characteristics. Here, CEACAM5 is linked to colorectal carcinoma.