There are several types of cancer clinical trials.

• Treatment trials: Most cancer clinical trials test new treatments or new ways of using existing treatments, such as new drugs, vaccines, surgical approaches, radiation therapy, or treatment combinations.
• Prevention trials: Cancer prevention trials involve healthy people. In most trials, participants either don’t have cancer but are at high risk, or have had cancer and are at high risk for developing a new one. These studies focus on cancer risk and ways to reduce it. There are two kinds of prevention trials:
  • Action studies (“Doing something”) focus on finding out whether actions people take—such as exercising more or eating more fruits and vegetables—can reduce the risk of getting cancer.
  • Agent studies (“Taking something”) focus on finding out whether taking certain medicines, vitamins, minerals, or dietary supplements (or a combination of them) may lower the risk of a certain type of cancer. Researchers also call agent studies chemoprevention studies.
• Screening trials: Cancer screening trials aim to test new ways to detect disease early, when treatment may be easier. An effective screening test reduces cancer-related deaths.
• Quality-of-life trials: These trials look at ways to improve the quality of life of cancer patients, especially those who have side effects from cancer and its treatment. They find new ways to help people cope with pain, nutrition problems, infection, nausea and vomiting, sleep disorders, depression, and other health problems. Quality-of-life trials might test:
  • Drugs, such as those that help with depression or nausea.
  • Activities, such as attending support groups, exercising, or talking with a counselor.
  • Ways to help families and caregivers cope with their own needs, as well as those of the person with cancer.

Each clinical trial has its own guidelines on who can participate as part of the study protocol. We call these guidelines eligibility criteria. They describe characteristics that all participants must share to join the clinical trial.

Common eligibility criteria for a cancer clinical trial include:

• Having a certain type and stage of cancer
• Treatment history
• Age range
• Other health conditions

Eligibility criteria can help researchers achieve accurate and meaningful results. These criteria also ensure that the study does not expose people who could be harmed to the risk.

For a treatment to become standard, it must first go through three or four clinical trial phases. The early phases make sure the treatment is safe. Later phases show if it works better than the standard treatment.

• A Phase 1 trial tests an experimental drug or device on a small group of people (around 20 to 80) to judge its safety, including any side effects, and to test the amount (dosage).
• A Phase 2 trial includes more people (around 100 to 300) to help determine whether a drug is effective. This phase aims to obtain preliminary data on whether the drug or device works in people who have a certain disease or condition. These trials also continue to examine safety, including short-term side effects.
• A Phase 3 trial gathers additional information from several hundred to a few thousand people about safety and effectiveness, studying different populations and different dosages, and comparing the intervention with other drugs or treatment approaches. If the FDA agrees that the trial results support the intervention’s use for a particular health condition, it will approve the experimental drug or device.
• A Phase 4 trial takes place after the FDA approves the drug or device. Researchers monitor the treatment’s effectiveness and safety in large, diverse populations. Sometimes, side effects may not become clear until more people have used the drug or device over a longer period of time.

Researchers spend many years testing investigational drugs in the laboratory before they can test the drug in humans. When initial laboratory research succeeds, they move the drug into human testing through a clinical trial. The Food and Drug Administration (FDA) closely monitors all phases of clinical trials.

For a treatment to become standard, it must first go through three or four clinical trial phases. The early phases make sure the treatment is safe. Later phases show if it works better than the standard treatment.

• A Phase 1 trial tests an experimental drug or device on a small group of people (around 20 to 80) to judge its safety, including any side effects, and to test the amount (dosage).
• A Phase 2 trial includes more people (around 100 to 300) to help determine whether a drug is effective. This phase aims to obtain preliminary data on whether the drug or device works in people who have a certain disease or condition. These trials also continue to examine safety, including short-term side effects.
• A Phase 3 trial gathers additional information from several hundred to a few thousand people about safety and effectiveness, studying different populations and different dosages, and comparing the intervention with other drugs or treatment approaches. If the FDA agrees that the trial results support the intervention’s use for a particular health condition, it will approve the experimental drug or device.
• A Phase 4 trial takes place after the FDA approves the drug or device. Researchers monitor the treatment’s effectiveness and safety in large, diverse populations. Sometimes, side effects may not become clear until more people have used the drug or device over a longer period of time.

Researchers spend many years testing investigational drugs in the laboratory before they can test the drug in humans. When initial laboratory research succeeds, they move the drug into human testing through a clinical trial. The Food and Drug Administration (FDA) closely monitors all phases of clinical trials.

Researchers use randomization in some clinical trials to prevent bias. Bias occurs when human choices or other factors unrelated to the treatments being tested affect the results of a trial. Randomization helps ensure that unknown factors do not affect trial results.

Randomization is used in all phase III and some phase II trials. These trials are called randomized clinical trials. A clinical trial consists of at least two groups depending upon the study protocol. A study protocol is a plan that describes the schedule of tests, procedures, medications and dosages, and the length of the study.

One group of patients will receive the experimental drug or treatment – this is the investigational group. One group of patients will receive either the standard of care or a placebo which has no therapeutic value – this is the control group. Placebos are almost never used in cancer treatment trials.

Comparing these groups to each other often clearly shows which treatment is more effective or has fewer side effects. If you are thinking about joining a randomized clinical trial, you need to understand that there is an equal chance you will be assigned to either group. Neither you nor your doctor chooses which group you will be in.

If you participate in a randomized clinical trial, the trial will assign you by chance to either an investigational group or a control group. The trial will determine your assignment at random, and no one will know which group you are in.

Regardless of which group they are in, all patients receive the same level of medical attention and care. In most clinical trials, the health of the participants is monitored both during and after the study period.