Microscopic examination by a pathologist is then necessary to identify molecular, cellular, or tissue architectural characteristics of epithelial cells. Types
Oral: Most oral cancers are squamous-cell carcinoma
Lung: Carcinoma comprises >98% of all lung cancers. Breast: Nearly all breast cancers are ductal carcinoma. Prostate: The most common form of carcinoma of the prostate is adenocarcinoma. Colon and rectum: Nearly all malignancies of the colon and rectum are either adenocarcinoma or squamous cell carcinoma. Pancreas: Pancreatic carcinoma is almost always of the adenocarcinoma type and is highly lethal. Ovaries: One of the most deadly forms due to late detection.Some carcinomas are named for their or the putative cell of origin, (e.g.hepatocellular carcinoma, renal cell carcinoma). Staging
Staging of carcinoma refers to the process of combining physical/clinical examination, pathological review of cells and tissues, surgical techniques, laboratory tests, and imaging studies in a logical fashion to obtain information about the size of the neoplasm and the extent of its invasion and metastasis. Carcinomas are usually staged with Roman numerals. In most classifications, Stage I and Stage II carcinomas are confirmed when the tumor has been found to be small and/or to have spread to local structures only. Stage III carcinomas typically have been found to have spread to regional lymph nodes, tissues, and/or organ structures, while Stage IV tumors have already metastasized through the blood to distant sites, tissues, or organs.
Certain combinations of mutations in the given progenitor cell ultimately result in that cell (also called a cancer stem cell) displaying a number of abnormal, malignant cellular properties that, when taken together, are considered characteristic of cancer, including:

the ability to continue to divide perpetually, producing an exponentially (or near-exponentially) increasing number of new malignant cancerous "daughter cells" (uncontrolled mitosis);
the ability to penetrate normal body surfaces and barriers, and to bore into or through nearby body structures and tissues (local invasiveness);
the ability to spread to other sites within the body (metastasize) by penetrating or entering into the lymphatic vessels (regional metastasis) and/or the blood vessels (distant metastasis).If this process of continuous growth, local invasion, and regional and distant metastasis is not halted via a combination of stimulation of immunological defenses and medical treatment interventions, the result is that the host has a continuously increasing burden of tumor cells throughout the body. Eventually, the tumor burden increasingly interferes with normal biochemical functions carried out by the hosts organs, and death ultimately ensues. Carcinoma is but one form of cancer—one composed of cells that have developed the cytological appearance, histological architecture, or molecular characteristics of epithelial cells. A progenitor carcinoma stem cell can be formed from any of a number of oncogenic combinations of mutations in a totipotent cell, a multipotent cell, or a mature differentiated cell.