Cancer is the uncontrolled growth and spread of cells that may affect almost any tissue of the body. Lung, colorectal and stomach cancer are among the five most common cancers in the world for both men and women. Among men, lung and stomach cancer are the most common cancers worldwide. For women, the most common cancers are breast and cervical cancer. More than 10 million people are diagnosed with cancer every year. It is estimated that there will be 15 million new cases every year by 2020.

Cancer causes 6 million deaths every year—or 12% of deaths worldwide. There are around 200 different types of cancer. Some are very common, while others are extremely rare - some types of blood cancer make up less than 1 in 100 new cases.

In the United States, approximately 8,600 children were diagnosed with cancer and about 1,500 children died from the disease in 2001. This makes cancer the leading cause of death by disease among U.S. children under age 15. Among the 12 major types of childhood cancers, leukemias (blood cell cancers) and brain and other central nervous system tumors account for over one-half of the new cases. About one-third of childhood cancers are leukemias; approximately 2,700 children (younger than 15 years) were diagnosed with leukemia in 2001. The most common type of leukemia in children is acute lymphocytic leukemia. The most common solid tumors are brain tumors (e.g., gliomas and medulloblastomas), with other solid tumors (e.g., neuroblastomas, Wilms’ tumors, and rhabdomyosarcomas) being less common.