Clinical Trials Information

Much of the following general information regarding clinical trials comes from the website of The Cancer Research Foundation of America at The Cancer Research Foundation of America (CRFA) is a national, non-profit health foundation with a single mission: the prevention and early detection of cancer through scientific research and education. The following series of questions and answers provides information about cancer-related clinical trials. These explanations are designed to educate eligible participants about opportunities for becoming involved in cancer studies and to help them make an informed decision about enrolling in a clinical trial.

What is a clinical trial?

A clinical trial is one of the final steps in translating laboratory research into new ways to prevent and treat disease. People enrolled in clinical trials help doctors find ways to improve health and cancer care. These trials are crucial for finding new cancer treatments and for determining which treatments are best suited for individual patients. Clinical trials, which are also called clinical studies and research protocols, answer scientific questions that help confirm that promising cancer advances are indeed safe and effective. Each study examines a different approach in hopes of finding better strategies for cancer prevention, diagnosis and treatment.

What are the different types of clinical trials that focus on cancer?

There are four different types of cancer trials.

  1. When people talk about clinical trials, they are most likely referring to treatment trials, which test new cancer treatments. Treatment trials evaluate the effectiveness of new cancer drugs, new types of surgery and radiation therapy, different combinations of treatments and new methods (like gene therapy) for stopping or reversing the course of disease.
  2. Prevention trials test strategies for reducing people’s risk of certain types of cancers. These strategies include the use of preventive agents, including dietary supplements—like vitamins, minerals and medicines—and lifestyle changes. Some prevention studies focus on preventing cancer in people who have never had the disease, while others try to reduce the chance of recurrence once a cancer has successfully been treated.
  3. Screening trials explore the best ways to find cancer in its early, most treatable stages.
  4. Quality of life/supportive care trials examine ways to make the lives of people with end-stage cancer as comfortable as possible and to help them maintain a high quality of life despite their disease.

Each clinical trial has its own list of criteria that people must meet in order to be eligible to participate in a study. For treatment trials, the eligibility requirements most likely designate that participants have a specific cancer type and stage. Other types of cancer trials, like screening, might only have an age requirement. Each clinical trial protocol lists the study’s eligibility requirements. Eligibility criteria are important to a study’s success. One reason why clinical trials include people with specific indications is that treatments are generally designed for only a select group of patients. Just as a doctor wouldn’t prescribe cough syrup to clear up a case of pink eye, researchers do not include patients in clinical trials of treatments from which they are not likely to benefit, and may even experience unpleasant side effects.

Another reason why clinical trials have such strict eligibility criteria is that the success of studies is based on statistically significant data. Depending on the number of patients included in a study, a certain proportion of its participants must demonstrate some benefit of treatment—or the drug being tested will not receive approval for widespread use. It is therefore important that a trial’s eligibility criteria restrict its group of participants to those who are most likely to improve from the treatment being tested.

How are clinical trials planned and carried out?

Long before a drug or procedure is given to people enrolled in a trial, scientists have examined it in several types of laboratory studies. These laboratory studies are completed not just once, but several times to try to ensure that the end result is reliable, reproducible and beneficial.

At this point, researchers develop a plan for the trial—called a protocol—that spells out the following details about how the study will be carried out:

  • The reason behind the study and its underlying hypothesis (what the investigators think will happen)
  • How many people need to enroll in the study (to make its results statistically significant)
  • Who is eligible to participate in the study
  • What drugs, if any, the participants will take or are taking
  • What medical tests the participants will undergo and how often
  • What types of information and data will be gathered

To determine the effectiveness of a particular agent, a clinical trial will compare its effect to that of the best existing alternative. To make the comparison as accurate as possible, researchers often randomize participants into clinical trial protocols. Generally speaking, randomization means that half of a trial’s participants (often called the treatment or study group) are selected on a random, unbiased basis to receive the new agent and the rest of the participants (the control group) receive the current best treatment standard.

Researchers in charge of the study look at the groups to make sure that there are no significant differences in their participants’ characteristics (age, sex, weight, etc.). The composition of the experimental and control groups are normally as similar as possible so that differences in outcome can be ascribed to the treatment. Sometimes the assignment of participants is double-blinded, so that the doctors who see the patients do not know in which treatment group their patients are enrolled. This is to help ensure that the data collection is unbiased. In blinded studies, patients do not know to which group they have been assigned, but the doctors do.

All centers and medical facilities that take part in a clinical trial follow the same protocol to make sure that all participants receive the same quality of care. Before enrolling in a clinical trial, however, participants must grant their informed consent to be part of the study.

What, exactly, is informed consent?

Informed consent is a safeguard that protects clinical trial participants. While informed consent does involve participant signing of an official document that lists the details of a trial and explains their rights, it entails much more than the initial agreement. Informed consent documents include the following general types of information:

  • Purpose of a clinical trial
  • Treatment procedures and schedule
  • Potential risks and benefits
  • Participant rights
  • Alternatives to participation
  • Contact information for ongoing communication about the trial

Informed consent is an interactive process in which the researchers provide ongoing explanations about the trial so that participants can make educated decisions about not only beginning, but also continuing with a study. Health care providers relay updates to participants and are available to answer questions or address concerns before, during and after the trial.

Because clinical trial participation is voluntary, people enrolled in clinical trials have the right to change their mind if they do not want to continue.

What are the different phases of clinical trials?

Clinical trials for cancer treatments generally progress in the same series of steps, called phases. Almost all clinical trials go through the following three phases before approval:

  1. Phase I trials are the first studies on human subjects. The primary objectives of phase I trials are to predict outcomes and evaluate side effects. These studies also determine the best way to administer drugs (by mouth, infused in the blood or injected into muscle), how often to administer drugs and what is the maximum safe dosage (since higher doses of most types of treatments are usually better at combating disease). Phase I trials typically enroll a small number of patients, sometimes as few as a dozen.
  2. After Phase I trials demonstrate that a treatment is safe, phase II trials are conducted to show that it is effective. Researchers continue to monitor safety during phase II trials, in addition to identifying which cancers are most successfully treated with the drug. A larger number of participants are involved in these trials, which may discover less common side effects.
  3. If a significant proportion of the participants enrolled in phase II trials respond to the treatment, phase III trials are used to compare the effectiveness of the treatment to those currently available to patients and to monitor the treatment’s side effects. Phase III trials enroll large numbers of participants—often hundreds or thousands of people—in doctors’ offices, clinics and cancer centers nationwide. Participants are randomly assigned to receive either the standard treatment, or the new, possibly better treatment.

If the phase III trial demonstrates that a treatment is better than the standard, researchers submit detailed results of the trial to the U.S. Food and Drug Administration (FDA), which scrutinizes the findings to determine if the results show a significant clinical benefit.

Once a treatment has FDA approval, the company that developed it can make it available for widespread use by the general public. Even after a drug has received FDA market clearance, however, the FDA continues to monitor the drug in phase IV trials to evaluate its long-term effects and cost-effectiveness. If dangerous or long-term side effects are found during these post-approval trials, the drug is taken off the market.

Who sponsors clinical trials?

Sponsors of clinical trials want to find better cancer treatments, explore possibilities for preventing cancer or improve screening and early detection. Trials are sponsored by government, industry and academic medical centers. Pharmaceutical companies and manufacturers of diagnostic technologies (for example, mammography equipment) that sponsor trials of their products must prove to the FDA that their products are both safe and effective. Many cancer-related clinical trials are sponsored by the National Cancer Institute (NCI), which is trying to expand access to clinical trials so that there will be more opportunities for patients who could potentially benefit from investigational therapies or procedures.

What regulations are in place to help make clinical trials safe?

Strict federal guidelines safeguard clinical trial participants by requiring that independent committees called Institutional Review Boards (IRBs) oversee clinical trials. There are over 3,000 IRBs in the United States that are typically comprised of a mix of local physicians, scientists, patient advocates, ethicists and administrators. IRBs are responsible for clearing study protocols before they are launched and closely monitoring trials after they are approved to ensure that participants are not exposed to excessive or unnecessary risks.

All clinical trials funded by the U.S. government—including all NCI trials—are subject to strict review by the Office of Human Research Protections of the U.S. Department of Health and Human Services.

In addition to these guidelines, the NCI has also established a quality assurance program that uses on-site monitoring of an institution’s clinical trial procedures, documents and data. During these checks, officials look for compliance with IRB and informed consent requirements; proper shipping, storage and administration of drugs; consistent process evaluation; and acceptable patient responses to treatment.

If IRBs or other groups that monitor data safety observe any of the following situations during the course of their reviews, they will stop the trial early to protect the clinical trial participants:

  • Evidence shows that risks of a treatment outweigh benefits
  • Participants are reporting unexpected or severe side effects
  • The experimental treatment is clearly less effective than the existing treatment.

On the other hand, IRBs can also end a trial early if the there is significant evidence early-on that a new intervention is effective so that it can be made available to the general public as quickly as possible. For example, Gleevec, a molecular-target therapy for a rare form of leukemia, was approved after phase II trials showed that it virtually eliminated all traces of the disease in all but one of the participants.

Why are clinical trials necessary?

Clinical trials are necessary to make sure new treatments, preventive agents and other medical advances are safe and beneficial before they are widely distributed. They also help health care professionals determine for what groups of people treatments work best and what doses can best help patients.

Cancer patients can benefit from trials because they are given either the existing standard of care or a promising new advance that researchers believe—and previous studies have suggested—could be even better than the existing treatment.

However, no one can accurately predict whether the experimental treatment will in fact be beneficial. Those considering enrolling in a trial should learn as much as they can about a study’s potential risks and benefits so that they can make an educated decision about whether or not to participate. The informed consent process furthers patient education and ultimately provides the context for making a decision.

What are the potential risks and benefits of clinical trials?

People choose to participate in clinical trials for many different reasons. Potential benefits associated with joining a clinical trial include:

  • Health care provided by leading physicians
  • Access to new drugs and interventions that are not yet widely available
  • Close monitoring of your overall health that involves addressing any side effects
  • Taking a proactive role in your own health care
  • Being among the first to benefit from promising medical approaches
  • Making a valuable contribution to cancer research

Although the agents examined in clinical trials have already gone through preliminary studies, they have not been tested on large numbers of people. For this reason, participating in a clinical trial can involve the following risks:

  • Unintended side effects of new drugs and procedures
  • New approaches may be ineffective in treating a disease or less effective than the current treatment standard.
  • Even if others benefit from the advance, it might not work for you.

Could I receive a placebo?

A placebo is a “sugar” or “dummy” pill that contains inert, inactive ingredients. Placebos are given to control-group participants in some blinded and double-blinded trials to gauge the effectiveness of possible treatments. While placebos are common in prevention trials, they are virtually never used in treatment trials, especially cancer-related trials.

The top priority of people involved with clinical trials is giving participants the best possible care. Therefore placebos—which contain no disease-fighting agents—are used in cancer treatment trials only if there is no existing treatment for the specific cancer targeted in the study.

To reiterate: cancer-related treatment trials almost never involve placebos. They would only be used for a study testing the effectiveness of a drug designed to treat a disease for which there is no treatment currently available. In this case, the participants randomized to the control group would receive a placebo, while those assigned to the treatment group would receive the drug being tested. If there is a possibility that participants will receive a placebo, it will be included in the protocol and it will be explained during the informed consent process. Therefore people will know they have a chance of receiving placebos before they decide to participate in the study.

When you decide to join a clinical trial, in essence you join a research team whose overarching goal is to fight cancer. You will work with a well-qualified group of health care professionals that may include doctors, nurses, social workers, dieticians and patient advocates. Depending on the type of trial, you could receive your care at a large cancer center, a university hospital, a local medical center or at your physician’s office.

The clinical trial team will administer any treatments or tests, monitor your progress and give you instructions about what you will need to do for the study. Because clinical trial participants are followed so closely and given a high level of individualized attention, participating in a trial might involve more appointments, doctor visits and tests than if you were not in a study. People involved with the study will continue to stay in touch with you after the trial ends to follow-up on the long-term effects of the intervention you received. Many participants involved in clinical trials enjoy this personalized care.

To ensure that the trial results are as reliable as possible, participants are expected to follow the research team’s instructions. That involves attending scheduled doctors’ appointments and tests, taking medicines on time, and completing logs or questionnaires if asked to do so. Your health care providers will relay your clinical responses to the center responsible for coordinating the study and analyzing the data of all the trial’s participants. After the trial is over, the trial researchers will use all the reported information to evaluate the effectiveness of the intervention tested in the study and recommend whether or not it should be available for widespread use.

Therefore, by joining a clinical trial, a participant not only takes an active role in his or her own health care, but also helps others fight future battles with cancer.

How do I join a clinical trial?

Your health care provider can help you locate trials you are eligible to join and can help you enroll in a study. Remember that the types of trials you are eligible for will depend on your medical history. Cancer prevention trials typically enroll people who have not had cancer (and may have higher cancer risks), while treatment trials involve a group of patients who have the same type of cancer.

In addition to speaking to your doctor, you can also learn about clinical trials on the Internet. Trials are run by research agencies such as the National Cancer Institute (NCI), as well as drug companies, hospitals and cancer centers.

Here are some places to begin your search if you have an interest in clinical trials:


National Center Complementary and Alternative Medicine (NCCAM) AND
National Cancer Institute
Association for Cancer Online Resources
For the PDQ (Physicians Data Query) Clinic Trials Database visit this NCI website or call 800-4-CANCER to search this comprehensive database of more than 1800 active cancer trials.
NIH sponsored site developed to provide patients with current info about clinical research studies. A bit confusing to use. Whe possible, use the "Focused Search" feature--it will narrow the results.
The HopeLink Clinical Trial Service is free and confidential. Find trials that support your cancer treatment, determine preliminary eligibility online, and submit your information to those conducting the trials.
Online version of the International Register of Clinical Trials Registers. No formal affiliation with any institution.
Center Watch Clinical Trials Center

Use this site to find a wealth of information about clinical research, including listings of thousands of active industry and government-sponsored clinical trials, as well as new drug therapies in research and those recently approved by the FDA. Designed to be an open resource for patients interested in participating in clinical trials and for research professionals. Not cancer-specific.
This database was launched by CCT, a United Kingdom-based company that offers free online access to its international database of randomized, controlled trials.
This site works like a dating service. You provide information about your condition and the site does a search to see if you're a match for any studies they're recruiting for.

New Medicines in Development

This free listing of pharmaceutical and biotech-sponsored trials is published by Pharmaceutical Research and Manufacturers of America (PhRMA). For a copy, call them at 202-835-3450. Check the database online at