These are all ways to learn how well the treatment works. A Phase II clinical trial lasts about 2 years. Volunteers sometimes receive different treatments. For example, a phase II trial could have 2 groups. Group 1 — People who receive the usual treatment for the condition. This is also called the standard treatment. It is the best treatment known. Or a phase II clinical trial could have 3 groups.
Volunteers in each group get a different dose of the treatment doctors are studying. If the phase II clinical trial shows the treatment works and is as safe as the regular treatment, doctors can do a phase III trial. Doctors use a computer program to put volunteers into different groups. The computer does this at random, which means by chance.
Each volunteer has an equal chance of going in any of the groups. The name for this process is "randomization. Using a computer to put volunteers in groups keeps the research staff from possibly changing the clinical trial results.
They might do this if they chose who went in which group. For example, they might think a certain volunteer would benefit from the new treatment. So they might put that person in the new-treatment group. But this could change the clinical trial results. Randomization helps avoid this. It is very important to use randomization when a clinical trial compares 2 treatments or more.
A phase III clinical trial tests a treatment that worked well for volunteers in a phase II clinical trial. Doctors use phase III to compare the new treatment with the standard treatment. They want to know if the new treatment is better, has fewer side effects, or both. How long a new drug takes to go through clinical trials. There is information about Drug testing and licensing Factors that affect how long trials take Drug testing and licensing All new drugs and treatments have to be thoroughly tested before they are licensed and available for patients.
There are many factors that affect how long it takes for a drug to be licensed. Factors that affect how long trials take The type of cancer Clinical trials for rarer cancers often take longer because there are fewer patients available to take part. The type of treatment Trials that use new methods of giving treatment, such as a new way to give radiotherapy for example, may take longer to set up and run.
The type of trial Some trials look at treatments to prevent cancer or ways of screening for cancer. The number of patients needed Statistics experts look at what the research team want to find out and the design of the trial, and then work out how many patients are needed. The follow up period Research teams look at how well people are doing for some time after they have treatment as part of a trial.
Any problems with the new treatment There may be problems with new drugs or treatments that the researchers don't know about until they run the trials. Problems with the new treatment may mean the trial takes longer to complete.
Related information Find a clinical trial Clinical trial results Understanding statistics in cancer research. Last reviewed 22 February Print page. Email this page. Sometimes, the safety and the effectiveness of the experimental approach or use may not be fully known at the time of the trial.
Some trials may provide participants with the prospect of receiving direct medical benefits, while others do not. Most trials involve some risk of harm or injury to the participant, although it may not be greater than the risks related to routine medical care or disease progression. For trials approved by IRBs, the IRB has decided that the risks of participation have been minimized and are reasonable in relation to anticipated benefits.
Many trials require participants to undergo additional procedures, tests, and assessments based on the study protocol. These requirements will be described in the informed consent document. A potential participant should also discuss these issues with members of the research team and with his or her usual health care provider. Anyone interested in participating in a clinical study should know as much as possible about the study and feel comfortable asking the research team questions about the study, the related procedures, and any expenses.
The following questions may be helpful during such a discussion. Answers to some of these questions are provided in the informed consent document. Many of the questions are specific to clinical trials, but some also apply to observational studies. Hide glossary Glossary Study record managers: refer to the Data Element Definitions if submitting registration or results information.
Search for terms. Where Are Clinical Studies Conducted? How Are Participants Protected? Clinical Trials In a clinical trial, participants receive specific interventions according to the research plan or protocol created by the investigators.
Observational Studies In an observational study, investigators assess health outcomes in groups of participants according to a research plan or protocol. To Top. National Library of Medicine U. Instead, Phase 2 studies provide researchers with additional safety data.
Researchers use these data to refine research questions, develop research methods, and design new Phase 3 research protocols. Study Participants: to 3, volunteers who have the disease or condition. Purpose: Efficacy and monitoring of adverse reactions. Researchers design Phase 3 studies to demonstrate whether or not a product offers a treatment benefit to a specific population. Sometimes known as pivotal studies, these studies involve to 3, participants. Phase 3 studies provide most of the safety data.
In previous studies, it is possible that less common side effects might have gone undetected. Because these studies are larger and longer in duration, the results are more likely to show long-term or rare side effects.
Purpose: Safety and efficacy. Learn more about Clinical Trials. Information about the investigator. Drug developers are free to ask for help from FDA at any point in the drug development process, including:.
Pre-IND application, to review FDA guidance documents and get answers to questions that may help enhance their research.
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