The most common type of colorectal carcinoma. It is characterized by the presence of malignant glandular epithelial cells invading through the muscularis mucosa into the submucosa. Histologic variants include mucinous adenocarcinoma, signet ring cell carcinoma, medullary carcinoma, serrated adenocarcinoma, cribriform comedo-type adenocarcinoma, and micropapillary adenocarcinoma.