Clinical trials are an important step in discovering new treatments for cancer and other diseases as well as new ways to detect, diagnose, and reduce the risk of disease. Clinical trials show researchers what does and doesn’t work in people. Clinical trials also help researchers and doctors decide if the side effects of a new treatment are acceptable when weighed against the benefits offered by the new treatment.

Clinical trials are a combination of interventional studies and observational studies conducted on volunteer patients. Interventional studies research how drugs, procedures, devices or lifestyle modifications affect a select group of patients with a common health condition. Observational studies research trends among select patients, through comparing released medical data and healthcare records or through monitoring a group with a common health condition. For example, investigators may observe a select group of women to learn about the effects of different lifestyles on adrenal health. Although observational study participants are not assigned an intervention as part of the study, they may continue with whatever interventions are part of their routine care, such as pharmaceutical prescriptions.

Clinical trials are just one type of research that’s done before a new treatment becomes available to people. New medicines must first be discovered, purified, and tested in preclinical trials before researchers even think about clinical trials. According to the American Cancer Society, about 1,000 potential medicines are tested before one makes it to clinical trials. On average, a new medicine to treat breast cancer has been studied for at least 6 years (and sometimes many more) before a clinical trial on it is started.