While several tumor biomarkers, including carcinoembryonic antigen (CEA) for colorectal cancer screening [14], carbohydrate antigen 125 (CA125) for ovarian cancer [15], and prostate-specific antigen (PSA) for prostate cancer [16], have shown utility in longitudinal disease monitoring, their clinical application remains limited. The gene discussed is CEACAM5; the disease is neoplasm.