Cancer Types

Cancer, also known as malignant tumor and neoplasm, is a medical condition characterized by abnormal and uncontrolled growth of cancer cells. In small quantity, these cells can exist in a healthy organism but are relatively harmless due to the work of natural killer cells that can recognize and destroy them. However, if particular co-stimulating molecules that let the immune system identify the malignant cells and trigger the lymphocytic response lack, cancer cells start to proliferate and may travel with the bloodstream (metastasize) to other parts of the organism. It is a separate mechanism, and failure of this type of defense does not necessarily presuppose the overall weakening or malfunctioning of the immune system (Gibson). In case of this abnormal proliferation of cancer cells, they eventually replace normally functioning cells which results in the failure of the damaged organ or tissue, and finally in fatal outcome. Inherited (genetic) factors are fully responsible for the formation of only 5-10% malignant tumors while environmental influences (such as tobacco and alcohol, radiation, pollution, dietary patterns, infections, etc.) are significant in as many as 90-95% of cases (Anand & Kunnumakkara 2097). Any organ or tissue of the organism can become the place of development of cancer cells. All in all, there are more than 200 types of cancer, in any type of cells (e.g. transitional cells, squamous cells and adenomatous cells in the bladder) and tissues (epithelial, connective, muscular tissue, etc.) of any of over 60 different organs in the body. Usually, there is more than one type of cancer developing in some organ of the body (Cancer Research UK). Malignant tumors are classified by histology (the type of cell that resembles the tumor, for example, carcinomas, lymphomas, sarcomas, cancer affecting squamous or glandular cells, etc.), and the location (the tissue presumed to be the origin of the tumor, for example, breast cancer, urine bladder cancer, lung cancer, etc.) (News Medical). Histology.According to the National Cancer Institute classification, five main categories of cancer types can be distinguished (medicinenet.com):Carcinoma, the most typical type of cancer, begins in the skin or in the tissue lining or covering internal organs: the genome of their epithelial cells is transformed so that these cells become malignant. Then these cancer cells metastasize and through the lymph nodes spread to other tissues and organs. The histological subtypes of carcinoma include adenocarcinoma, squamous cell carcinoma, adenosquamous carcinoma, large and small cell carcinoma, and anaplastic carcinoma, each affecting a certain type of epithelial cells.Sarcoma, transformation of mesenchymal cells begins in bone, cartilage, fat, muscle, blood vessels, or other connective or supportive tissue. They are much less frequent than carcinomas, and are further subdivided according to the type of tissue they affect: Osteosarcoma, a malignant tumor beginning in the bone;Chondrosarcoma, the cancer type affecting cartilage; Sarcoma botryodies, the type affecting the genitourinary tract tissues;Ewing’s sarcoma, a malignant bone tumor usually most common among children; Malignant peripheral nerve sheath tumor, transformation of the connecting tissue around nerves;Malignant hemangioendothelioma (vascular tumors);Various types of soft tissues sarcoma. Leukemia …