Scientists have made great progress over the last few decades in the
understanding of how and why cancer cells grow. They've also made significant
headway in discovering ways to prevent, screen for, and treat cancer.
The hallmark of these discoveries is the clinical trial - a carefully
designed study that evaluates such things as promising new screening tests
or medications, surgical procedures, and even lifestyle changes. No new
cancer treatment can be made available in Canada unless it has undergone
rigorous testing through clinical trials to ensure it is safe and effective.
How a clinical trial works
Each trial is designed to test a particular treatment on a specific type
of cancer, often at a particular stage of the cancer's development. The
trial might be designed to test whether the new treatment makes people
feel better. Each clinical trial can take many years - often as long as
a decade - to organize and carry out. It involves several stages:
- Phase I trial
This first study evaluates a drug's safety and determines how best to
provide it, such as how much to give, how often, and by what means (i.e.,
injection, orally).
- Phase II trial
This next phase continues to test the drug's safety and begins to evaluate
how well patients respond to it.
- Phase III trial
This stage of study expands the testing to include a larger number of
patients and to compare the new drug with treatments already available
to see if it produces better results. Cancer trials are different than
other clinical trials in that cancer patients are never given a placebo
if a standard treatment is available. A placebo is an agent that looks,
feels and smells like the drug under review but has no real effect.
- Phase IV trial
This final phase takes place after the drug has received government
approval outside the experimental setting. The purpose of this study
is to monitor the drug for long-term effectiveness and side effects.
Patients are usually randomly assigned by a computer to receive either
a standard treatment (one that has already been approved and is in general
use as a cancer treatment) or the new experimental therapy. In many cases,
patients and investigators are blinded. This means that neither
knows which agent the patient is receiving until the end of the study.
It helps investigators determine, without bias, whether the experimental
therapy is better than the standard approach.
Who can join a clinical trial
Patients who participate in clinical trials must meet strict criteria
to participate. For example:
- patients may be required to have only the kind of cancer being studied.
Those who have medical conditions in addition to their cancer may be
excluded.
- investigators may be looking for patients in a particular age group
- sometimes study organizers want only people who have received a certain
kind of standard treatment. In other cases, they enroll only those who
have not responded to such standard therapy.
Before the clinical trial begins, patients receive detailed information
on the test drug's potential benefits and risks as well as any known side
effects. They also learn what their rights and responsibilities will be
throughout the trial. They must sign a consent form before being enrolled
in the study. Patients can remove themselves from the study at any time.
What to expect
Once enrolled in the clinical trial, patients are monitored closely for
side effects and how well they respond to the treatment. As a standard
part of any study, patients visit their doctor regularly for tests and
to complete questionnaires about how they feel. This rigorous testing
can continue for a very long time. There are usually many health care
centres across the country - and even in other countries - involved in
the later phases of the clinical trial. Each centre monitors a number
of patients and reports study data to a coordinating centre.
Research ethics board
A committee of experts usually made up of physicians, other health professionals,
and patient advocates closely monitors each clinical trial. This group
ensures the trial is ethical, that the aim of the trial is closely adhered
to, and that patients' rights are protected. The committee also keeps
track of the trial's progress and can recommend a trial be halted early
if a new drug proves to be extremely effective or extremely harmful. If
the drug is proven effective, study findings are made available immediately.
However, this does not mean that the drug or treatment will be available
right away.
Advantages of being involved in a clinical trial
There are many advantages to being involved in a clinical trial. For example:
- you may be among the first group of people to receive a new, and possibly
much improved, therapy. You may also benefit from being involved in
clinical trials that test screening methods that can detect cancer at
its early stages.
- you receive the best health care from leading specialists at major
health centres who closely monitor your progress
- you may contribute to the potential discovery of effective new treatments
or prevention strategies may help countless other people living with
cancer.
Possible drawbacks
But there are some potential drawbacks. For example:
- there are no assurances that the new drug is any better than what
you've tried before
- the new therapy may carry some unexpected side effects
- being involved in a clinical trial may be time-consuming and inconvenient.
If you are interested in participating in a clinical trial, talk to your
doctor. He or she will answer any of your questions and can tell you whether
you qualify for a clinical trial that is being organized in your region.
Your doctor will also be able to explain in more detail some of the issues
about joining a clinical trial that are not discussed here.
Additional Resources
For more information about clinical trials, call the Canadian
Cancer Society's Cancer Information Service toll-free at 1-888-939-3333.
Clinical trials: what you need to know: a guide for people with cancer –
Canadian Cancer Society (CCS)
OntarioCancerTrials.ca – Ontario Cancer Research Network (OCRN)
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