The key variables studied include histological characteristics of each type of cancer, clinical and TNM stages, baseline laboratory results (Carcinoembryonic antigen (CEA) for colorectal cancer, Prostate-Specific Antigen (PSA) for prostate cancer, hemoglobin level, etc.), clinical characteristics including sign and symptoms, family history of cancer, diagnostic and treatment modalities a patient received for each type of cancer. The gene discussed is CEACAM5; the disease is cancer.