There are two main types of trials or studies: interventional and observational.
Interventional trials aim to find out more about a particular intervention, or treatment. People taking part are put into different treatment groups, so that the research team can compare the results.
Observational studies aim to find out what happens to people in different situations. The research team observes the people taking part, but they don’t influence what treatments people have. The people taking part aren’t put into treatment groups.
There are different types of trials within these two groups.
Pilot studies and feasibility studies
Pilot studies and feasibility studies are small versions of studies which are sometimes done before a large trial takes place.
Feasibility studies are designed to see if it is possible to do the main study. They aim to find out things such as whether patients and doctors are happy to take part, and how long it might take to collect and analyze the information. They don’t answer the main research question about how well a treatment works, for example.
Pilot studies are small scale versions of the main study. Pilot studies help to test that all the main parts of the study work together. They may also help answer the research question. Sometimes the research team includes the information collected during the pilot study in the results of the main study.
Prevention trials look at whether a particular treatment can help prevent cancer. The people taking part don’t have cancer.
These trials can be for the general population or for people who have a higher than normal risk of developing a certain cancer. This could include people with a family history, for example.
Screening means testing people for the early signs of cancer before they have any symptoms. As with prevention trials, screening trials can be for the general population. Or they can be for a group of people who have a higher than normal risk of developing a certain cancer.
Researchers may plan screening trials to see if new tests are reliable enough to detect particular types of cancer. Or they may try to find out if there is an overall benefit in picking up the cancer early.
Treatment trials are done in stages, called phases. The early phases aim to find out more about the safety and side effects of a new treatment. Later phases aim to see if a new treatment works better than the current treatment.
For trials that compare two or more treatments, the people taking part are put into a treatment group at random. Randomized trials are the best way to get reliable information about how well a new treatment works. We have more information about randomization.
Multi-arm multi-stage (MAMS) trials
A multi arm trial is a trial that has several treatment groups (arms) as well as the standard treatment group (the control group).
Multi-arm multi-stage (MAMS) trials have the same control group all the way through. But the other treatment groups can change as the trial goes on.
The research team may decide to stop recruiting people to a particular group. This could be because they have enough people to start looking at the results. Or because early results show the treatment isn’t working as well as they’d hoped.
And they may add new treatment groups as new drugs become available to look at. This means they don’t have to design and launch a brand new trial, each time they want to research a new treatment. So it helps get results quicker.
The Stampede trial for prostate cancer is an example of a MAMS trial.