What Is Adenocarcinoma Cancer?

Can you please give me some information on adenocarcinoma? A friend has been diagnosed with stomach cancer and the type of tumor is called adenocarcinoma. I can’t find any information on it.

Cancers or malignant tumors are classified according to the type of tissue from which they originate. The broadest division of cancers separates the carcinomas, tumors which arise from epithelial tissues, and the sarcomas, which arise from all other tissues. An epithelium is a tissue that covers the internal or external surfaces of the body. Thus, the skin is an epithelium, as is the lining of the mouth, stomach, intestines, bladder and so on. Complicating this is the fact that tissues which are derived in fetal life from an epithelium, like the liver, pancreas, breast, prostate, and parts of the kidneys; although they do not line or cover the body, are considered to be of epithelial origin. Therefore, cancers of these organs are carcinomas.

Within the category of carcinomas, there are many subdivisions, corresponding to the types of different epithelium from which they may be derived. Therefore, the skin, which consists of a type of epithelium called squamous epithelium, can give rise to squamous cell carcinomas. There are other epithelial cells also present in the skin, basal cells, which give rise to basal cell carcinomas, and melanocytes, which give rise to melanomas.

The situation becomes even more complicated when one realizes that many tissues can change the type of lining epithelium which they contain, so that a carcinoma may develop from a type of epithelium not normally present in the organ. This happens in the lung for example, when the cells lining the bronchi, the small tubes carrying air in and out of the lungs, change from their normal columnar epithelium to squamous epithelium, and then go on to become cancerous, creating a squamous cell carcinoma of the lung. Ordinarily there are no squamous cells in the lungs, but certain irritants or carcinogens, notably tobacco smoke, can cause the columnar cells to degenerate into squamous cells, which can then become cancerous.

The adeno- in adenocarcinoma to which you refer is the prefix meaning gland. Therefore, an adenocarcinoma is a cancer originating in glandular cells. Adenocarcinomas are very common, occurring in the lungs, from small glands in the bronchi; in the stomach from one of the several types of glands lining it; and in the colon, breast, prostate and in other locations. Therefore, in describing an adenocarcinoma, one would need always to include the organ where it originates. Adenocarcinomas arising from different organs can often be identified by the pathologist microscopically, even when they are removed from a different location where they may have metastasized, such as the liver. Thus, it is common to refer to an adenocarcinoma of the stomach which has metastasized to the liver, or one from the colon metastasized to the lungs.

Adenocarcinomas are the most common cell type of cancer that we see, since they include almost all breast cancers, all colon cancers, all prostate cancers, and a fair percentage of lung cancers. Whereas the cause of many squamous cell cancers is pretty well known, sun exposure in the case of squamous cell carcinoma of the skin, tobacco smoke in the case of squamous cell carcinomas of the lung, the cause of most adenocarcinomas is still unknown, and is the subject of intensive research. Intriguing associations have been described, such as the association of early menstruation with carcinoma of the breast, or lack of fiber associated with colon cancer, but these are only associations, not proof. In fact recent research appears to indicate that the amount of fiber in one’s diet has nothing to do with the development of colon cancer, although lack of exercise does have such an association.

Almost all carcinomas, including adenocarcinomas are always fatal if untreated, but with modern early detection, improved techniques of surgical removal, and advanced chemotherapy and radiation therapy, the cure rates have improved enormously over the past 50 years.

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