Thinking about joining a clinical trial can feel daunting. There's a lot of unfamiliar language, and it's hard to know what you're actually agreeing to. This guide walks you through the process step by step — so you know what to expect at every stage and feel confident asking the right questions.
Trials have specific eligibility criteria — a list of conditions that describe the people the study is designed for. Some criteria relate to your diagnosis (for example, a specific type of cancer that has come back after previous treatment), some to your current treatment, and some to your general health. Meeting the criteria doesn't guarantee a place in the trial — it just means you might be suitable and are worth discussing with the research team.
You might be told about a trial by your oncologist or haematologist, or you might find one yourself through ClinicalTrials.gov or through a charity website. Either way, the first step is usually a conversation with the research team — often by phone or email — to see if you might fit the study criteria.
If you seem eligible, you will be invited for a screening visit — usually at the hospital or clinic running the trial. This visit is to confirm your eligibility before you are formally enrolled. It typically includes blood tests, a physical examination, and a review of your medical records. Some studies require a scan or a tissue biopsy at this stage.
Importantly, attending a screening visit does not commit you to joining the trial. You can change your mind at any point, including after screening, without any impact on your usual care.
Your rights: Participating in a clinical trial is always voluntary. You can withdraw at any time and for any reason. Choosing not to participate — or withdrawing — will never affect the quality of the standard care you receive from your medical team.
Before you can formally join a trial, you will go through the informed consent process. This is one of the most important parts of trial participation, and it must happen before any trial-specific procedures are carried out.
A member of the research team — usually the research nurse or a doctor — will take you through a Patient Information Sheet (PIS). This document, which is written in plain English and approved by an Independent Review Board (IRB) or ethics committee, explains:
You should be given as much time as you need to read the information sheet, ask questions, and discuss it with family or friends before you decide. You should never feel rushed. Once you are satisfied and ready to proceed, you will be asked to sign a consent form — and the research team member will countersign it. You keep a copy.
Once enrolled, you will attend regular clinic visits as set out in the trial schedule. These visits are similar to your normal oncology appointments but may include additional assessments — extra blood tests, more frequent scans, or questionnaires about how you are feeling. The research team will explain exactly what each visit involves.
In a randomised trial, you will be assigned to one of two or more treatment groups by a process like drawing lots — neither you nor your doctor chooses which group you are in. This randomisation is designed to make the comparison fair. In some trials, neither you nor your doctor knows which treatment you are receiving during the study; this is called blinding, and it is used to prevent unconscious bias in how outcomes are assessed.
All clinical trials have safety monitoring in place. An independent group called a Data Safety Monitoring Board (DSMB) reviews the trial data at regular intervals — including safety data — and has the authority to stop the trial early if there are unexpected safety concerns, or if the evidence already shows a clear benefit or clear lack of benefit.
You will also have a direct point of contact — usually the research nurse — for any concerns or symptoms that arise between visits. You will be given a 24-hour emergency contact number before you start the trial.
When your involvement in the trial ends, the research team will discuss what happens next with your care. If the trial treatment has been beneficial for you, you may be able to continue receiving it through a compassionate use programme or standard prescribing if the treatment has been approved. The research team will explain your options at that stage.
Your contribution — whether or not the treatment worked for you individually — helps build the evidence base that improves care for future patients. We are grateful to everyone who participates in our trials. If you have questions about joining one of our studies, please contact us or visit our patient information page.
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For PatientsQuestions to Ask Your Doctor About Trial Participation
For PatientsWhat Is a Tissue Biopsy and Why Is It Needed?
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