Cancer is a group of diseases involving abnormal cell growth with the potential to invade or spread to other parts of the body. Benign tumors do not spread to other parts of the body. Possible signs and symptoms include a lump, abnormal bleeding, prolonged cough, unexplained weight loss and a change in bowel movements. While these symptoms may indicate cancer, they may have other causes.] Over 100 cancers affect humans. Tobacco use is the cause of about 22% of cancer deaths. Another 10% of cancer death is due to obesity, poor diet, lack of physical activity and drinking alcohol. Some other major facts that cause cancer by certain infections, exposure to ionizing radiation and environmental pollutants. Approximately 5-10% of cancers are due to inherited genetic defects from parents.