To improve the screening effectiveness, some researchers combined the fecal microbiome with fecal occult blood (48–50), tumor markers [mainly the carcinoembryonic antigen (CEA)] (44, 50) and basic demographic information [such as age, sex, and body mass index (BMI)] (51, 52), and these combinations resulted in the improvement of the CRC screening ability. The gene discussed is CEACAM5; the disease is colorectal carcinoma.