Treatment trials test experimental drugs, new combinations of drugs, or new ways to use surgery or radiation therapy.
Prevention studies look for better ways to prevent disease in people who’ve never had a disease or to prevent a disease from returning. They may include medicines, vitamins, vaccines, minerals, or lifestyle changes.
Diagnostic studies try to find better tests or procedures for detecting certain diseases or health conditions.
Screening studies test the best ways to detect certain diseases or health conditions.
Quality of Life studies (or Supportive Care studies) explore ways to improve the comfort and quality of life for people with a chronic (continuing) illness.