Types of clinical trials
Most clinical trials start with cancer research in a laboratory (laboratory-based), where scientists try to understand cancer at its most basic and deepest level. If a new approach seems promising in the laboratory, the next step may be to test it on animals. If the research continues to show positive results, the next step is to do clinical testing and have people participate.
The main types of clinical trials in the field of cancer research are:
|Type of clinical trial||Description|
Looks for ways to reduce the risk of developing cancer in healthy people who have not had cancer or people who are at a higher risk of developing a certain type of cancer. Researchers may also conduct prevention trials in people with a history of cancer to try to prevent it from coming back (recurring) or to reduce the chance of developing a new type of cancer.
Examples of prevention trials include:
Screening and early detection
Tests or evaluates the best ways to find cancer early in people who do not have any signs or symptoms of cancer. Finding cancer early can often improve the results of treatment and increase the chances of survival. People who have a higher than average risk of developing a certain type of cancer or people who have been exposed to cancer-causing substances (such as tobacco) may be offered a chance to participate in a screening and early detection clinical trial.
Examples of screening and early detection trials include studying:
Looks for better ways to diagnose or stage cancer.
Examples of diagnostic trials include studying:
Tests or evaluates new cancer treatments and usually compares new cancer treatments with ones that already exist (standard treatments). This is the most common type of clinical trial involving people with cancer.
Examples of treatments tested in clinical trials include:
Studies how to reduce the impact of cancer and improve comfort levels and quality of life for people with cancer and cancer survivors. These are also called quality of life trials.
Examples of supportive care trials include studying:
Randomized clinical trials
Researchers conduct phase III and sometimes phase II clinical trials as randomized clinical trials. In these studies, the participant is randomly assigned to the experimental group (receiving the new, experimental treatment) or a control group (receiving standard treatment). This study design is ethical when it is not known which treatment is better.
Sometimes participants in the control group may be given a look-alike pill or an injection that does not contain any active drug (placebo). This study design is ethical if it is not known if there is benefit or risk from taking the experimental treatment.
People who participate in randomized clinical trials have an equal chance that they will be assigned to either the experimental or control group. A computer usually assigns random numbers to participants. The number a person is assigned will decide whether or not they are in the experimental or control group. The doctor who conducts the trial (principal investigator) does not decide whether a participant is in the control or experimental group.
Blinded clinical trials
Researchers may conduct clinical trials as blinded clinical trials. In these studies, the researcher knows if a participant is in the experimental group or a control group, but the participants do not know what group they are in. This is because if a person knows what treatment they are getting, it may affect their response. For example, those who know they are getting the experimental treatment might expect it to work better and report positive or hopeful signs because they want to believe they are getting well. This could throw off the results of the study.
In double-blinded studies, neither the participants nor the researchers know which treatment group participants are in or what treatment they are receiving. This study design is preferred as it prevents both the participant and the researchers from doing things that may bias the scientific results.
A description of the extent of cancer in the body, including the size of the tumour, whether there are cancer cells in the lymph nodes and whether the disease has spread from its original site to other parts of the body.
Stages are based on specific criteria for each type of cancer.
The process of determining the extent of cancer in the body based on exams and tests is called staging.
Taking action against all cancers
The latest Canadian Cancer Statistics report found that of all newly diagnosed cancers in 2017, half are expected to be lung, colorectal, breast and prostate cancers. Learn what you can do to reduce the burden of cancer.