Cancer is a diseases in which a group of cells have uncontrolled growth and destroys adjacent tissues, and spreads to other locations in the body by the way of lymph or blood. These three malignant properties of cancers differentiate them from benign tumors. Common factors leading to cancer include - tobacco, diet and obesity, infections, radiation, lack of physical activity, and environmental pollutants. The presence of cancer can be suspected on the basis of symptoms, or findings on radiology. Definitive diagnosis of cancer, however, requires the microscopic examination of a biopsy specimen. While cancer can affect people of all ages, and a few types of cancer are more common in children, the overall risk of developing cancer increases with age. In 2007 cancer caused about 13% of all human deaths worldwide (7.9 million).