- cancer
- cancer genetics
- cancer risk
- cardiac catheterization
- carotid artery disease
- celiac disease
- chiropractic
- chlamydia
- cholecystectomy
- cholesterol
- chronic fatigue syndrome
- chronic venous insufficiency
- cirrhosis
- colon cancer
- colonoscopy
- colorectal cancer
- common cold
- communication
- complementary and alternative medicines
- congenital heart disease
- constipation
- contraception
- contraception IUDs
- coronary artery disease
- coronary bypass
- cramps
- Crohn's disease
- Cushing's disease
- cystic fibrosis