•    Treatment trials test new treatments, new combinations of drugs, or new approaches to surgery or radiation therapy.
     •    Prevention trials look for better ways to prevent disease in people who have never had the disease or to prevent a disease from returning. These approaches may include medicines, vitamins, vaccines, minerals, or lifestyle changes.
     •    Diagnostic trials are conducted to find better tests or procedures for diagnosing a particular disease or condition.
     •    Screening trials test the best way to detect certain diseases or health conditions.
     •    Quality of Life trials (or Supportive Care trials) explore ways to improve comfort and the quality of life for individuals with a chronic illness.