Cancer is a disease caused when cells in the human body divide uncontrollably and spread into surrounding tissues. Cancer is caused by changes in DNA. Most cancer-causing DNA changes occur in sections of DNA called genes. These changes are also called genetic changes.
In other words, cancer is a genetic disease causing uncontrolled growth of abnormal cells in the body. In a healthy body, a mechanism exists that kills off these abnormal cells. However, cancer can develop when this control mechanism stops working.
Cancer can start almost anywhere in the human body, which is made up of trillions of cells. Normally, human cells grow and divide to form new cells, as the body needs them. When cells grow old or become damaged, they die, and new cells take their place.
When cancer develops, however, this orderly process breaks down. As cells become more and more abnormal, old or damaged cells survive when they should die, and new cells form when they are not needed. These extra cells can divide without stopping and may form growths called tumors.
Many cancers form solid tumors, which are masses of tissue. Cancers of the blood, such as leukemias, generally do not form solid tumors.
Cancerous tumors are malignant, which means they can spread into, or invade nearby tissues. In addition, as these tumors grow, some cancer cells can break off and travel to distant places in the body via blood or the lymphatic system and form new tumors far from the original site.
Cancer is the second leading cause of death in the world. But survival rates are improving for many types of cancer, thanks to the improvements in cancer screening and cancer treatments.
For many people, cancer can be treated successfully. In fact, more people than ever before, lead full lives after cancer treatment.
