What is Cancer?
Cancer is a group of over 200 distinct diseases that are characterized by abnormal growth and development of cancer cells which invade and destroy adjacent tissues (tumors or neoplasms) and/or spread throughout the body through circulatory or lymphatic systems (metastasis). Cancer can affect any part of the body, virtually any organ and tissue at any age and both genders but it is most common in people older than 50 years. Different types of cancer affect every third person in developed countries and according to World Health Organization (WHO) cancer is the leading cause of death throughout the world.
Human body consists of different types of cell which grow and divide only when necessary. Since the cell cycle is limited cell division is essential for regeneration of tissues and for normal functioning of organism. However, sometimes can occur uncontrolled division of the cells which start to form a lump which is known as tumor or neoplasm. Tumors are either benign or malignant. Benign tumors are formed of cells which are usually made of cells that are very similar to normal cells, have limited capacities to grow and do not cause cancer. Benign tumors also do not spread in other parts of the body, do not jeopardize one's life and if removed with surgery usually do not reoccur. In contrary to benign tumors, malignant tumors are made of abnormal - cancer cells which grow and spread very aggressively. If left untreated malignant tumors invade and destroy the adjacent tissues but cancer cells can also spread throughout the body through circulatory and lymphatic systems causing damage to other vital organs.. Tumors that are caused by metastasized cancer cell via blood or lymphatic system are called the secondary cancer, while the site where the malignant tumor was primarily formed is referred as primary cancer.