Cancer (medicine), any of more than 100 diseases characterized by excessive, uncontrolled growth of abnormal cells, which invade and destroy other tissues. Cancer develops in almost any organ or tissue of the body, but certain types of cancer are more lethal than others.
Cancer is the leading cause of death in Canada and second only to heart disease in the United States. One of the greatest risk factors for cancer is prolonged or repeated exposure to carcinogens—chemical, biological, or physical agents that cause the cellular damage that leads to cancer. The details of how carcinogens cause cancer remain unclear. One theory is that exposure to carcinogens, when combined with the effects of aging, causes an increase in chemicals in the body called free radicals. An excessive number of free radicals causes damage by taking negatively charged particles called electrons from key cellular components of the body, such as DNA. This may make genes more vulnerable to the mutating effects of carcinogens.
While everyone is at risk for cancer, some people or groups are at greater risk than others. Age is the greatest risk factor for cancer; 78 percent of cancers are diagnosed at age 55 and older. People who use tobacco, drink heavily, are physically inactive, eat a poor diet, are regularly exposed to carcinogens in their occupation or have prolonged and unprotected exposure to sunlight or ultraviolet radiation are all at increased risk for certain cancers. Among racial/ethnic groups:
African Americans had higher incidence rates than whites for cervical, colon and rectum; esophageal, kidney and renal pelvis; larynx; liver and intrahepatic bile duct; lung and bronchial; multiple myeloma; oral cavity and pharynx; pancreatic; prostate; and stomach cancers.
Whites had higher incidence rates than African Americans for brain and other central nervous system; Hodgkin’s and Non-Hodgkin’s lymphoma; leukemia; melanoma of the skin; thyroid; and urinary bladder cancers.
Asian/Pacific Islanders in Ohio had lower incidence rates than other races for most cancer sites/types, but did have a higher incidence of liver and intrahepatic bile duct cancer than white or African Americans.
Poverty, insurance status, genetics, health risk behavior and culture all play a role in the burden of cancer disparities. While everyone should follow cancer prevention and screening guidelines, those at highest risk for specific cancers should be particularly attentive to screening recommendations and to symptoms of these cancers and seek prompt medical attention if they occur.