Cancer is a group of diseases involving abnormal cell growth with the potential to invade or spread to other pats of the body. These contrast with benign tumors, which do not spread. 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 can also have other causes. over 100 types of cancers affect humans.
Tobacco use is the cause of about 22 percent of cancer deaths. Another 10 percent are due to obesity, poor diet, lack of physical activity or excessive drinking of alcohol. Other factors include certain infections, exposure to ionizing radiation and environmental pollutants. In the developing world, about 15 percent of cancers are due to infections such as Helicobacter pylori, Hepatitis B, Hepatitis C, human papilomavirs infection, HIV, etc.