Cancer that begins in glandular (secretory) cells. Glandular cells are found in tissue that lines certain internal organs and makes and releases substances in the body, such as mucus, digestive juices, or other fluids. Most cancers of the breast, pancreas, lung, prostate, and colon are adenocarcinomas.

Adenocarcinoma in-situ is a condition in which abnormal cells are found in the glandular tissue that lines certain internal organs, such as the uterus, cervix, lung, pancreas, and colon. Adenocarcinoma in situ, which occurs most often in the cervix, may become cancer and spread to nearby normal tissue. Also called AIS.