Carcinoma is a type of malignant cancer that originates in the epithelial cells. The epithelium, which is composed of these cells, is the main tissue covering the internal and external organs of the body. The most common types of carcinomas occurring in the United States include lung cancer, breast cancer and colon cancer. Carcinomas can invade adjacent areas of the body and metastasize, or spread, to distant areas via the lymph nodes and bloodstream.

Pre-malignant Carcinoma

In its earliest stage, carcinoma is referred to as pre-malignant carcinoma or carcinoma in situ (CIS). The cancer, in this stage, is localized. Pre-malignant carcinoma or CIS usually develops within an organ, such as the lung or breast. In some cases of CIS, tumors, such as colon polyps, are produced. However, in the majority of cases, the cancer has not advanced to the tumor stage and is considered a lesion.

Invasive or Malignant Carcinoma

Most cases of carcinoma are classified as either invasive or malignant. In other words, the disease has spread to adjacent organs or has metastasized into other areas of the body by way of the blood or lymph nodes. An invasive or aggressively growing tumor that can result in death is considered malignant.

Neoplasms

Carcinomas that have developed into tumors are often classified as neoplasms. A neoplasm results from neoplasia, or the abnormal division and reproduction of cells.

Cytology

Cytology, or the study of cells, plays a major role in the prognosis of carcinomas. Low grade cells are cancerous cells that look similar to healthy cells. High grade cells, on the other hand, look vastly different from normal cells and are often found in advanced stages of the disease.

Staging and Treatment of Carcinoma

Four stages are assigned to carcinomas for diagnostic purposes. Stage 0 signifies pre-malignant carcinoma. Stage I carcinomas are localized and generally can be treated and cured. Stage II and III tumors have progressed to adjacent areas of the body, while Stage IV represents carcinomas that have metastasized. Treatment is facilitated using radiation, chemotherapy or surgery or a combination thereof.

Source:

"Carcinoma.com: Carcinoma"

"National Cancer Institute: A to Z List of Cancers"

"National Cancer Institute: A to Z List of Cancers"

More Information:

"eHow: Carcinoma Definition"

"Livestrong: Tubular Carcinoma"