Over the last several decades, survival rates for many types of cancers and other diseases have improved dramatically. Much of that improvement can be traced to the tireless efforts of cancer researchers, and the organizations and donors who fund their research.

According to the National Institutes of Health, there are two types of clinical research: observational studies and clinical trials. Observational studies observe people in normal settings, and during these studies, researchers gather information, group volunteers according to broad characteristics, and compare changes over time. Observational studies sometimes help researchers discover new opportunities for clinical trials, which are research studies that aim to evaluate medical, surgical, or behavioral interventions. Clinical studies are often how researchers learn if new drugs and treatments are safe and effective.

Clinical trials are somewhat routine, though they tend to capture the attention of the general public during public health crises. For example, much attention was paid to clinical trials during the recent COVID-19 outbreak as researchers hurried to develop a vaccine for the novel coronavirus.

Cancer researchers utilize clinical trials to advance treatments and as part of ongoing efforts to find a cure for all types of cancer. In the United States, these trials must go through various phases as outlined by the Federal Drug Administration. During these phases, treatments are tested, and researchers try to find appropriate dosages while also documenting any potential side effects. A clinical trial must go through three phases before a drug can be approved for use:

  • Phase I: A phase I clinical trial tests an experimental treatment on a small group of people, typically healthy people between the ages of 20 and 80. Phase I aims to judge the safety of a treatment and find any side effects while also determining dosage.
  • Phase II: More people are typically needed for a phase II clinical trial, which may require as many as 300 participants. The NIH notes that a goal of phase II trials is to obtain data regarding the effectiveness of the drug on people who have certain diseases or conditions. Safety, particularly in regard to short-term side effects, is also studied during a phase II trial, which can last for several years.
  • Phase III: Different populations and different dosages are studied during phase III trials, which may require the participation of several hundred, if not thousands, of people. Positive results during a phase III trial typically result in FDA approval.

Once a drug is approved by the FDA, a phase IV trial is conducted to study the effectiveness and safety among large, diverse populations. The NIH notes that the side effects of a drug may not become clear until more people are studied over very long periods of time, which is why drugs are often studied even after they’re approved by the FDA. Information about participating in clinical trials in the US can be found at www.nih.gov.