Cancer is a group of diseases involving abnormal cell growth with the potential to invade or spread to other parts of the body. These contrast with benign tumors, which do not spread.

Addiction to a mood- or mind-altering drug, such as alcohol or cocaine.

Chronic fatigue syndrome (CFS) is a complicated disorder characterized by extreme fatigue that can’t be explained by any underlying medical condition. The fatigue may worsen with physical or mental activity, but doesn’t improve with rest.

Chronic liver disease in the clinical context is a disease process of the liver that involves a process of progressive destruction and regeneration of the liver parenchyma leading to fibrosis and cirrhosis. “Chronic liver disease” refers to disease of the liver which lasts over a period of six months.

Complex regional pain syndrome (CRPS) is a chronic (lasting greater than six months) pain condition that most often affects one limb (arm, leg, hand, or foot) usually after an injury. CRPS is believed to be caused by damage to, or malfunction of, the peripheral and central nervous systems.

Congestive heart failure (CHF) is a chronic progressive condition that affects the pumping power of your heart muscles. While often referred to simply as “heart failure,” CHF specifically refers to the stage in which fluid builds up around the heart and causes it to pump inefficiently. You have four heart chambers.

Crohn’s disease is an inflammatory bowel disease (IBD). It causes inflammation of your digestive tract, which can lead to abdominal pain, severe diarrhea, fatigue, weight loss and malnutrition. Inflammation caused by Crohn’s disease can involve different areas of the digestive tract in different people.

Cystic fibrosis is a hereditary disease that affects the lungs and digestive system. The body produces thick and sticky mucus that can clog the lungs and obstruct the pancreas. Cystic fibrosis (CF) can be life-threatening, and people with the condition tend to have a shorter-than-normal life span.