Clinical Trials

What are clinical trials?

Clinical trials are research studies for testing new ways of

  • Treating cancer
  • Managing side effects and symptoms
  • Screening and diagnosis
  • Improving patient quality of life.

Often what’s being tested is a drug to treat cancer or manage its symptoms, but it can also be a diagnostic test, a possible way of preventing cancer, a medical device, or a treatment of another kind, such as radiation therapy.

Some clinical trials test drugs, treatments, or procedures that are new: they have not been used on humans before, although they have been tested in a laboratory. Other trials test existing therapies to learn more about how best to use them – for example, to see if there are additional cancer types for which they are useful.

Clinical trials are a vitally important part of cancer research. If you are a cancer patient, it is because of clinical trials that the treatment you are receiving is known to be safe and effective. Regulatory agencies such as Health Canada rely on clinical trials for evidence of the safety and efficacy of new treatments when deciding whether to approve them.

More information

Participating in clinical trials

Clinical trials depend on the participation of cancer patients to work. By participating in a clinical trial, you are helping to advance cancer research for future patients.

You may wish to participate in a clinical trial in order to help contribute to cancer research; or because of the chance to receive a new cancer treatment.

Your participation in a clinical trial is completely voluntary. You can always withdraw from a clinical trial at any time, without penalty.

To participate in a clinical trial, you have to be referred by a doctor. If there is a clinical trial you would like to join, talk with your healthcare professional about it – they will be able to tell you whether or not the trial is right for you. If it is, you can ask them to refer you.

If you are interested in finding a clinical trial to join, try looking for one on one of the websites listed below under “Where to find clinical trials”.

Informed consent

If you sign up for a clinical trial, you will be asked for your informed consent. Informed consent means that in order for you to consent to join the trial, and to continue participating in it, you have to be adequately informed about what is being asked of you and what are the risks and benefits of participating. It is the responsibility of those conducting the trial to keep you informed and make sure they have your consent. Health Canada requires informed consent for all clinical trials.

Risks and benefits

If you are considering joining a clinical trial, you should talk with your health care professional about the potential risks and benefits of the trial for you. Every trial is different.

In general, however, there are usually a few potential benefits:

  • You get to participate in the advancement of medical science.
  • The new drug may be beneficial to you. It may even be more effective for you than existing drugs, or it may have fewer side effects. However, if you are in a randomized control trial, you may not get the new drug, but the existing standard drug instead – and you will not know which you are getting.

Potential risks usually include:

  • The new drug may be worse for you than existing drugs – it may be less effective for you, or you may experience worse side effects.
  • The trial will involve travel to the hospital or wherever the trial is being conducted from, and possibly even stays in the hospital, which can take up a lot of your time.

For more on the potential risks and benefits of clinical trials, see Clinical trials and drug safety: Possible benefits (Health Canada).

Questions to ask

If you are considering joining a clinical trial, these are some questions you may want to ask of the clinical trial provider:

  • Why is this trial being done?
  • What are my other options (standard treatments other studies)? What are their advantages and disadvantages?
  • What kind of tests and treatments does the study involve? How often are they done?
  • Will this require an extra time commitment on my part?
  • How could the study affect my daily life?
  • What side effects might I expect from the study treatment? (Remember that there can also be side effects from standard treatments and from the disease itself.)

For the elderly

Even if you are older, you should still consider joining a clinical trial. Although patients enrolled in clinical trials are typically young, most people being treated for cancer are elderly. It is important that clinical trials for cancer include elderly people: older bodies do not always respond to drugs in the same way as younger ones; and older people are also more likely to have other conditions at the same time (comorbidities) that could affect how they respond to treatment. For information on clinical trials for the elderly, refer to PolicyLab’s guide on clinical trials for the elderly.

Phases of clinical trials

Before a clinical trial begins, the drug being trialled has already undergone pre-clinical testing in laboratories. This involves testing the drug on cells, tissue samples, or animals in order to determine whether it has potential. If it does, a clinical trial can take place.

Clinical trials proceed in four phases. Each phase builds incrementally on the results of the previous phase.

Phase 1

This is the first time the drug is tested on humans. Phase 1 seeks to find out what is the safe range of dosages for the drug, what dosage is needed for it to be effective, and whether there are any other issues with safety or side effects. It involves a small number of people—typically 20 to 80.

Phase 2

The drug is given to a larger group of people – typically 100 or more – in order to determine its efficacy against a specific type of cancer.

Usually the participants must all have the same type of cancer. However, some newer drugs are tumour-agnostic, or personalized medicine, meaning that they target a genetic mutation that many different types of cancer can have. In that case the participants may have different types of cancer, but their tumours must all have the genetic mutation that the treatment targets.

Phase 3

In phase 3, the treatment is compared with an existing treatment that is commonly used for the same disease, in order see whether it is more effective than the existing treatment. This phase involves many more people – anywhere from a few hundred to several thousand.

Phase 3 trials also monitor side effects and gather information on for whom the drug is most effective, and how it will fare on the market.

Typically, phase 3 is a randomized control trial: each patient is assigned at random to get either the new treatment or the existing one. The trial may be blind, which means participants don’t know which treatment they’re getting; or it may be double blind, which means those conducting the trial do not know which patients are getting which treatment, and neither do the patients. This is a way of reducing the chance of bias. The randomized control trial is considered the most reliable way of gathering evidence that new treatment works.

With personalized medicine or tumour-agnostic treatments, there may not be an existing standard treatment to compare with, because the new treatment may be the first one for this particular genetic mutation. In that case, a randomized control trial may not be possible, and the drug cannot be compared with anything.

Phase 4

The fourth phase of a clinical trial takes place after the drug has been approved by regulatory authorities (e.g. by Health Canada) and has been made available on the market. It aims to discern the long-term impact of the drug on patients’ health and quality of life by following up with the phase 3 patients. Note that few drugs actually reach this phase.

Where to find clinical trials

Below is a list of websites with databases or registries of clinical trials. Even the databases from other countries often have information about clinical trials being conducted in Canada – there is a great deal of international collaboration in cancer research.

It is important to note that these registries contain trials that are accepting patients, that have been completed, and that are no longer accepting patients. It is generally possible to search within these databases just for trials that are accepting patients.

In Canada

Canadian Cancer Trials is a national, bilingual directory of clinical trials for cancer patients. You can search for clinical trials by province, by cancer, by cancer/trial centres, by city, by drug, or by a personalized search. For each trial, they provide a link to a third-party web page with specific information.

They also have a sub-website for cancer trials in each province: Alberta – British Columbia – Manitoba – New Brunswick – Newfoundland and Labrador – Nova Scotia – Ontario – Prince Edward Island – Quebec – Saskatchewan

The Canadian Cancer Trials Group is a network of cancer researchers across many institutions that runs clinical trials for cancer within Canada and internationally. They have a list of active clinical trials organized by cancer type.

Internationally is a US-based registry that provides user with federally and privately supported clinical trials that are conducted in the United States and around the world. The web page has almost 128,000 trials listed in 179 countries. Note that this website is not cancer-specific; it includes clinical trials of all kinds. It is possible to search for just cancer clinical trials, however.

National Cancer Institute: Coordinating Center for Clinical Trials is a division of the U.S. National Cancer Institute that not only provides information on new trials, but also acts as an information resource for patients who are thinking about clinical trials.

Cancer Research UK: Find a clinical trial. Cancer Research UK provides an online database for cancer trials in the United Kingdom. This site provides patients and their families information about clinical trials, including how they work, their benefits and risks, what to ask your doctor, and more.

European Organisation for Research and Treatment of Cancer (EORTC) provides a database listing the 200 active clinical trials they conduct, as well as other that they are involved in around the world, including in Canada.

Australian Cancer Trials has a searchable database of clinical trials in Australia and New Zealand, as well as information about how clinical trials work, their risks and benefits for participants, etc.

Open Clinical Trials in Canada


To learn more about clinical trials, watch this CCSN webinar by Dawn Richards, Director of Patient and Public Engagement at Clinical Trials Ontario:

Video: What is a Clinical Trial?


Canadian Cancer Society. (n.d.). Types and phases of clinical trials. Retrieved October 2020 from

Health Canada. (2020). Clinical trials and drug safety. Retrieved October 2020 from

Cancer Research UK. (2019). What clinical trials are. Retrieved October 2020 from

Australian Cancer Trials. (2020). What is a clinical trial? Retrieved October 2020 from

N2 Canada. (2020). How it works. Retrieved October 2020 from