Variables in the multivariate linear regression model initially included sex, age, BMI, family history of colorectal cancer, smoking status, disease stage tumor location, grade, mucinous component, signet ring cells, Crohn's-like reaction, peritumoral lymphocytic reaction, tumor infiltrating lymphocytes (TIL), CIMP, MSI, BRAF mutation, KRAS mutation, PIK3CA mutation, TP53 expression, CDKN1A expression, CTNNB1 score, PTGS2 expression, and FASN expression. The gene discussed is PIK3CA; the disease is colorectal cancer.