Clinical Trials: Cutting-Edge Care

Participating in a clinical trial can yield big benefits for cancer patients, but it's important to know the risks first.

By Jennifer Warner
WebMD Feature

Reviewed by Ann Edmundson, MD, PhD

For every big story or spike in the value of a pharmaceutical stock prompted by a new cancer drug, there is probably a clinical trial to thank. But just because a drug or treatment makes headlines doesn't mean it's going to suddenly be available to all who might benefit from it. In fact, attention-grabbing, experimental treatments are usually only available through controlled clinical trials for several years after their initial effectiveness has been shown.

Cancer patients often have the most to gain from participating in these clinical trials, especially if currently available treatments prove ineffective. Even so, according to the American Cancer Society, only about 4% of adult cancer patients take part in clinical trials.

Recent advances in genetics and medicine, such as the mapping of the human genome, have fueled an explosion of research into new, targeted cancer therapies that treat cancers more accurately and with fewer side effects than current methods. That means the number of clinical trials available to cancer patients is growing rapidly, and they are playing an increasingly important role in the treatment of a wide variety of cancers.

"Clinical trials have always been extremely important to the development of new agents and interventions for many years," says Mary McCabe, acting director of communication and education at the National Cancer Institute (NCI). "Now, the opportunities are growing because we are in an era where we can take advantage of advances in molecular biology to develop new agents."

Deciding whether to take part in a clinical trial is a very personal decision and one that should be thoroughly discussed with healthcare providers, family, and friends. But a clear understanding of what clinical trials are, how they work, and the potential risks and benefits of participation is a critical element in making an informed decision.

Why Are Clinical Trials Needed?

Until the 20th century, there were relatively few medicines and treatment options available for cancer. So doctors relied on their own experience and education to care for their patients. But as more and more therapies and drugs were introduced, doctors needed a way to compare treatments and see what worked best for treating particular illnesses and disease.

Clinical trials emerged in the mid-20th century as studies designed to test and often compare treatments in a particular group of people. This allowed doctors to base their decisions on what therapies worked in a large number of people rather than just a few of their own patients.

Now, new medicines or therapies must first undergo rigorous testing for safety and effectiveness in clinical trials before they are approved for use by the FDA. These trials allow researchers to determine the proper dosing of new drugs and compare how well they work with what's already available.

Only a small fraction of the drugs developed in laboratories ever make it to the clinical trial stage. Before a clinical trial begins, the drug must be evaluated in pre-clinical laboratory studies and/or in animal studies.

Clinical trials are conducted in stages called phases. A phase I trial generally involves a small number of patients (usually less than 50) and its primary goal is to determine if the treatment is safe for use in humans. Doctors closely monitor the participants to determine what is the maximum safe dose of the treatment that can be given without serious side effects.

Phase I trials are generally the most risky, and for this reason they enroll patients who have few remaining treatment options or haven't responded to currently available options.

A phase II clinical trial is larger and is used to determine if the treatment is effective. Depending on the prevalence of the type of cancer the treatment is designed for, up to 100 patients may be enrolled in a phase II clinical trial.

In a phase II trial, researchers are looking to see if the experimental treatment has a beneficial effect in a significant number of the participants. If an acceptable percentage of the patients respond well to the drug, it will go to a phase III trial.

Phase III trials are the largest and usually the longest stage of the process. In this stage, the drug or intervention is compared to the current standard of care for that particular type of cancer to determine if it works better. Several hundred patients are involved from many different regions or countries and are monitored for their response to the drug as well as any potential side effects.

Many of these phase III studies are randomized and double blinded. Randomization means that similar groups of participants are randomly selected to receive either the experimental treatment or the current standard of treatment. In a double-blinded study, neither the patient nor their doctor knows which treatment the patient receives. This is done to eliminate any potential biases the doctor or patient might have.

A placebo -- an inactive ingredient or pill -- may be used in a phase III trial to determine if adding another agent to the current treatment produces a better result than the standard treatment alone. But even the placebo group always receives at least the current standard of care. Only very rarely are there cases in which there is a "no treatment" placebo group in cancer clinical trials.

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