Adenocarcinoma is a cancer that originates in glandular tissue. Because there is glandular tissue throughout the body, adenocarcinoma can be found in many different organs, including the lungs, colon, pancreas, cervix and esophagus. The organ in which adenocarcinoma originates determines the type of adenocarcinoma the patient has. Adenocarcinoma of the lung is a different disease, with a different prognosis, than adenocarcinoma of the pancreas, for example. Although each specific type of adenocarcinoma has its own specific staging criteria, there are some general principles that pertain to all adenocarcinomas.
Stage 0 adenocarcinoma, also called adenocarcinoma in situ, consists of localized malignant cells which have not yet become an invasive cancer. This is the earliest form of adenocarcinoma and is sometimes referred to as pre-cancer. Removing a stage 0 adenocarcinoma eliminates the possibility that the cells will develop into a true cancer.
Stage 1 adenocarcinoma is generally a localized tumor that has not spread beyond the organ of origin. Depending on the type of cancer, there may be subdivisions within stage 1 that further define how advanced the cancer is. For example, most organs have several layers of tissue. Although a cancer may be stage 1, a tumor that is confined to one area of an organ is less advanced than a tumor that extends into the outer tissue layers. The subdivisions of stage 1 reflect this distinction.
Stage 2 and 3
Stage 2 and stage 3 adenocarcinomas have progressed beyond the original cancer site, and may have invaded additional organs. There will generally be lymph node involvement with stage 2 and stage 3 adenocarcinomas. The distinction between stage 2 and stage 3 depends upon the extent of the spread of the cancer, and is different depending on the type of adenocarcinoma.
Stage 4 adenocarcinoma is characterized by cancer cells that have spread, or metastasized, to organs far beyond the original tumor site. Stage 4 adenocarcinomas are generally referred to as inoperable cancers because of the multiple tumor sites and the difficulty in locating all of the metastasized cancer cells.
TNM Staging of Adenocarcinoma
Each stage of adenocarcinoma has an additional staging designation, determined by the TNM system: "T" refers to tumor, "N" refers to nodes and "M" refers to metastases. Each letter is followed by a number that indicates the degree of involvement. T can range from T0 to T4, depending on the size and extent of the tumor. The lymph node involvement is also scaled from 0 to 4, with N0 meaning there is no lymph node involvement and N4 indicating extensive involvement. M will be either M0 or M1, meaning either that there are metastases (M0) or that there are no metastases (M1).