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Understanding Clinical Trials

Clinical trials are research studies that are designed to evaluate new drugs or treatment strategies, and determine whether they are effective. Clinical trials often represent the best options for treatment, especially for those whose cancer is unable to be surgically removed.

Each clinical trial is designed to find a new or better way to treat cancer. Sometimes this involves a new drug that has not yet received FDA approval. In other instances, trials involve combining two existing therapies to look at whether they work better when used together. There are numerous approaches to studying the way we treat and manage cancer, so multiple studies are always happening all over the world. In order to evaluate these new ideas, researchers must study cancer patients as they are being treated (in most cases).

Currently, there are hundreds of ongoing clinical trials in the United States. Although clinical trials are an important component of cancer care and are crucial for improving cancer treatment, fewer than 5% of cancer patients currently participate in clinical trials because they are uninterested or unaware that they exist, have difficulty finding an appropriate clinical trial that may be of benefit to them, or are ineligible to participate in a clinical trial because of prior treatment interventions.

Available trials are not all created equally. Clinical trials are conducted in four phases. Each phase is designed to establish certain information about the potential new drug or treatment strategy. This information can include overall safety, risks, and effectiveness compared to standard therapies. The earlier the phase, the less is known about the therapy under investigation.

Phase I trials are designed to determine safety issues, such as:

  • Dose ranges and how they are tolerated
  • How a drug works within the body
  • Side effects, particularly as they relate to different doses
  • Whether side effects are reversible

Phase I trials usually include a small number of patients for whom standard therapies have been unsuccessful, or for whom no other treatments are available. These trials may involve more risk to the patient, but may also represent a last hope for those who have exhausted all of their options.

Phase II trials are meant to determine the effectiveness of a treatment or strategy in a particular population, using the findings from phase I. For instance, if a drug’s safe dose range is established in phase I, then phase II may focus on treating only patients with a certain type of lung cancer with that dose range. These trials are generally slightly larger than phase I trials.

Phase III trials are designed to compare a new treatment with existing treatments (referred to as standard therapy) to establish effectiveness. These trials are generally much larger. This is because differences in success rates may be small, so a large number of patients are needed to make the difference “statistically significant.”

There is typically more than one treatment group in a phase III trial. One group will receive the study treatment, and another group may receive standard therapy. The studies are designed so that patients are placed into different groups at random. Nobody knows which type of treatment each patient is receiving. This is done to prevent any “bias” from impacting the results of the trial, and is called “randomization.” Randomization is very important in research because it improves the “statistical significance” of the trial’s findings. Learn more about phase three trials.

Phase IV trials generally happen after a treatment has been approved and is on the market. The purpose is to further monitor the risks, benefits, and side effects of a treatment over a longer period of time and in a larger sample of patients than in phase III trials. The results of phase IV trials directly contribute to the improvement of products for patient use.

More information about clinical trials can be found at