Cancer is a group of diseases which arises from a single mutation resulting in uncontrolled cell proliferation and spread (metastasis) to nearby tissue or secondary organs. The abnormal mass of cells is termed as tumor or neoplasm. The tumor is benign when the cells are not invasive. When the cells become capable of invading the surrounding tissue, it is called malignant, i.e., cancer.

Cancer can be treated by surgery, that is, removing tumor when it is in the benign stage. Chemotherapy is used to kill cancerous cells. It includes intravenous injection, cream or ointment, oral drugs (liquid, capsule, and tablet). Radiation is used alone or with the combination of surgery or chemotherapy. Other treatments include immunotherapy (use of cytokine, antibody), hormonal therapy, stem cell transplants.

About 30-50% of cancer can be prevented by improving lifestyle, avoiding tobacco or alcohol, and raising awareness about infection, exposure to carcinogens and environmental pollution.