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Clinical trials

Clinical trials for cancer aim to find better treatments and to improve outcomes for patients. 


On this page:

What is a clinical trial?

Clinical trials for cancer treatments aim to find new and better treatments and to help to improve outcomes in cancer patients. 

A clinical trial is a piece of research in humans that studies new ways of preventing, screening and treating physical problems. All the standard medical treatments that we use today have been tested in clinical trials.

Cancer clinical trials look at how cancer is diagnosed and treated. They look at the drugs used, how those drugs affect people and how they affect their cancer.

  • Some clinical trials use new drugs or treatments to treat the cancer.
  • Some clinical trials look at what happens when existing drugs or treatments are used in new combinations.

Some trials don’t use drugs or treatments at all, but focus on the quality of life of someone in cancer treatment, or look at the scans and tests used to find more information about their cancer.

For more detailed information on clinical trials, see our factsheet Cancer and clinical trials.  

Am I suitable for a trial?

Not all trials are suitable for all patients, even if they have the same cancer type.

Trials often need patients who are similar in ways including: age, sex, stage of cancer, previous treatments and other medical conditions. For this reason, trials have very strict rules. This means that some people can be included in the trial but some are not suitable and so will not be able to take part.

You may also need a medical examination and additional tests to check if you can take part in the trial.

Open Cancer Trials

Making a decision

If you a suitable for a trial, it can be hard to make a decision about whether or not to take part. Here are some things to think about:


  • The trial treatment might be better than the standard treatment.
  • Your doctor may find out more about your cancer due to extra tests only available on clinical trials.
  • You may be helping to improve cancer treatment for future patients.
  • Your clinical trial team will organise all your hospital appointments as the trial recommends.
  • You will be closely monitored by a team of doctors and trial nurses.


  • The trial treatment may be as good as the standard treatment but it might not be better. 
  • You might have some side-effects after taking the trial treatment.
  • You might have to make more visits to the hospital than patients who are on the standard treatment.
  • If you are on a randomised trial using a new drug you may still only receive the standard treatment.

Asking lots of questions can help you think about the pros and cons. See some questions to ask about clinical trials.

Before you start your treatment, you will be asked to read a detailed patient information sheet. After you have reviewed all the information, ask your doctor or nurse if you have any questions.

Once you have read the patient information sheet and spoken to the doctor or nurse, you will be asked to provide informed consent. This means that you understand the trial and agree to take part.

Informed consent

Giving consent means that you understand the trial and agree to take part. You cannot be part of a clinical trial if you have not given your permission. If you want to take part you will be asked to read a consent form. 

The consent form explains: 

  • Why the trial is being run 
  • What it hopes to achieve 
  • What the possible side-effects and risks are 
  • Why you have been invited to take part

It is important that you understand everything about the trial before you agree to take part. This is called informed consent. If you want to take part you will fill in and sign the consent form. You can change your mind about taking part, even if you have signed the consent form or started your trial treatment.

Cancer Trials Ireland has further information about current trials in Ireland.

What happens if I want to leave the trial?

You can withdraw from a clinical trial at any time. If the doctor or nurse feels that the trial would benefit you or your cancer long term, they will discuss this with you and make it clear – but the choice is yours.

If you decide you don’t want to be part of the trial any more, you will be offered the standard treatment instead.

Irish Cancer Society publications
Cover of the cancer and clinical trials factsheet
Cancer and clinical trials factsheet
This factsheet is to help cancer patients understand more about cancer and clinical trials.

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