Being involved in a clinical trial has risks and benefits. Being informed and asking lots of questions can help you make a decision.

A clinical trial is a research study that uses human volunteers to try to answer a specific question.

Whenever a new arthritis medicine or breast cancer treatment hits the market, clinical trials are an important step in the approval process.

Clinical trials are held for different reasons, says the National Institutes of Health (NIH):

• Treatment trials test experimental treatments, new combinations of medicines, or new types of surgery or radiation therapy.
• Prevention trials test new ways to prevent certain diseases or prevent a disease from returning.
• Diagnostic trials look at new tests or procedures that diagnose disease.
• Screening trials test new methods for finding disease.
• Quality of life trials look at new ways to improve quality of life for people with chronic illness.

Clinical trials are done in phases, designated as I through IV. Each phase has a different purpose, the NIH says:

• Phase I trials use a small group of people, usually 20 to 80, to check the safety, dosage, and side effects of a treatment.
• Phase II trials expand to 100 people to 300 people and look at how well a treatment works and how safe it is.
• Phase III trials include 1,000 people to 3,000 people and try to confirm the results of the earlier trials and compare the new treatment with other commonly used treatments. More data are collected to help determine safe usage.
• Phase IV trials are done after the treatment is approved for the general public. These trials collect additional information on risks and benefits of the new treatment.

The good news is that most clinical trials test treatments that already have shown some promise of working better than existing therapies.

All United States clinical trials must also be overseen by an institutional review board (IRB) at each site participating in the research. The IRB oversees and regulates the trials.

All clinical trials have guidelines that describe the criteria for participants. To ensure that a trial's results are reliable, people are included or excluded from the trial according to these criteria. In most trials, one group of patients is given a standard treatment. Another group receives the therapy being tested.

As a clinical trial participant, you must sign an informed consent document that gives many details about the study and what you can expect. Your participation is voluntary and any negative effects may require changes to your treatment or removal from the study. You have the right to leave at any time and will be withdrawn right away if you have negative health effects.

Here are the pros to consider:

• You may be among the first to benefit from a new treatment.
• You'll be helping others by contributing to medical research.
• You'll be closely watched and will receive high-quality medical care.

Weigh those against the cons:

• Experimental treatments may bring unpleasant or serious side effects.
• The treatment may not work for you, or it may end up working less well than the available treatment.
• Participating may require more of your time and energy than a normal treatment regimen. There may be more tests and doctor visits, complex dosage requirements, or hospital stays.
• Your health plan may not cover all your costs.
• You may have to change doctors.

Before you sign up, talk with your family and your doctor to decide if this is a good choice for you.

The NIH also advises that you get answers to these questions before participating:

• What's the purpose of the study?
• Who will be in the study?
• Why do researchers believe the experimental treatment being tested may be effective?
• What kinds of tests and experimental treatments are involved?
• How do the possible risks, side effects, and benefits of the study compare with my current treatment?
• How might this trial affect my daily life?
• How long will the trial last?
• Who will pay for the experimental treatment?
• What type of long-term follow-up care is part of this study?
• How will I know the experimental treatment is working? Will I receive the results of the trial?