Group of more than 100 distinct diseases characterized by the uncontrolled growth of abnormal cells in the body. Cancer affects one in every three persons born in developed countries and is a major cause of sickness and death throughout the world. Though it has been known since antiquity, significant improvements in cancer treatment have been made since the middle of the 20th century, mainly through a combination of timely and accurate diagnosis, selective surgery, radiation therapy, and chemotherapeutic drugs. Such advances actually have brought about a decrease in cancer deaths. The billions of cells that make up a tumor are descended from a single cell that has found a way to escape the normal controls of its growth. This loss of control is caused by damage of the genetic material in the cell, specifically the long, coiled chains of deoxyribonucleic acid (DNA) found in the chromosomes. Such damage can arise during cell division, be induced by environmental agents, or be inherited. Regardless of how the damage is caused, genetic changes and the abnormal growth pattern that they promote are passed on to a cell's progeny (its daughter cells) as the cell divides. Important determinant of the way a tumor will grow how fast it will give rise to clinical symptoms, and how early it may be diagnosed. For example, a tumor of the skin located on the face is usually detected very early, whereas a sarcoma located in the deep soft tissues of the abdomen can grow to weigh 2 kilograms before it causes much of a disturbance. The site of origin of a tumor also determines the signs and symptoms of disease that the individual will experience and influences possible therapeutic options. The most common tumor sites in females are the breast, lung, and colon. In men the most frequently affected sites are the prostate, lung, and colon. Cancer is to a great degree a disease of the elderly, and age is thus a very important factor in cancer development. However, individuals of any age, including very young children, can be stricken with the disease. Benign and malignant tumors produce a number of effects in an individual that vary depending on the location of the tumor, the tumor’s functional activity, and any acute events that occur as the tumor mass grows and evolves. Metastatic tumors (those that result from the spread of the primary tumor) can produce the same consequences. A tumor affects normal bodily functions by compressing, invading, and destroying normal tissues and also by producing substances that circulate in the bloodstream .In order for cancer to be diagnosed as early as possible, an individual should be aware of symptoms that may be related to the disease. The standard diagnostic workup begins with a detailed clinical history of the person. A complete physical examination, including laboratory tests such as a complete blood count and a urinalysis, is made. Diagnostic imaging using X-ray, ultrasound, computed tomography (CT) scans, or magnetic resonance imaging(MRI) may be essential, and radioisotopes can be used to visualize certain organs or regions of the body.