An Anatomy Lesson
Lips, teeth, gums, buccal mucosa (inner lining of the lips and cheeks), the floor of the 
mouth, palate, and also the small area behind the wisdom teeth. All these areas are those that make up the oral cavity, next to the pharynx (posterior third of the tongue and throat, and tonsils) are the regions that are affected by malignant cells. Moreover, between the throat and stomach, the tube through which pass, among other substances, drink and food, is the esophagus. It is located just immediately behind the trachea and an adult has a length of around 25 centimeters.
Tumors that are located in this area are of two types, depending on the nature of malignant cells: carcinomas and adenocarcinomas. The first, squamous-cell carcinomas because of its shape resembling a flat-flake, originate in the layer of cells lining the inner walls of the mouth and esophagus. In the early stages, these tumors are localized, and only when the disease progresses and spread of malignant cells can speak of invasive cancer. Adenocarcinomas, on the other hand, are those tumors that are located in the glandular cells (those that secrete fluids to the mucous lining of the walls of organs).
When the disease spreads, the malignant cells reach the lymphatic system, a complex network of vessels, valves, ducts, glands and organs located throughout the body that help protect the body fluid environment through the production, filtration and transport of lymph The fluid containing the cells that fight infection and disease. Cancer cells, for transmission, using precisely the lymph nodes, small clusters of defensive cells. In the case of oral cancer, these nodes often travel to the neck, although it may reach other parts of the body (liver, lungs, brain and even bones), as with tumors arising in the esophagus.