Cancer, uncontrolled growth of cells in the body, can originate in nearly any tissue. Genetic, environmental, viral and behavioral factors can contribute to transforming healthy cells into cancerous cells. Often cancer forms a centralized tumor, but it can also invade adjacent tissues, spread to other parts of the body (metastasize) or be diffused throughout the body, as is the case with leukemia.

Treatment

Categorization and recommended treatment of cancerous cells depends on the type of cancer, the level of resemblance to surrounding tissue (grade), and the degree of invasion of surrounding tissues (stage).

Treatments for cancer typically involve surgical removal of cancer cells and/or killing cancer cells with heat, cold, chemicals, radiation or high-intensity sound or light waves. Many treatment programs combine therapies, attacking the cancer on multiple fronts. Combination treatment programs enable customization to the unique physiologies, conditions and preferences of individual people.

While not all cancers can be cured, researchers have made tremendous strides in cancer treatment in the last 40 years—treatments have become increasingly specific, targeted and effective. Peripheral medical advances have also resulted in much more effective symptom management and comfort (palliative) care.