About clinical trial results

The results of clinical trials are often published in specialist medical journals. There are some plain English summaries of trial results on our Clinical trials database.

When are trial results available ?

Factors that affect trial results
How do I find the results of a trial I have taken part in?

Clinical trial results on our website

Other places to look for trial results

Systematic reviews

When are trial results available?

It can take a long time to get results from a trial.

Sometimes, the trial will have results available within a year. This could be the full results or partial results (often called the interim analysis). It is more usual for trial results to take between 2 and 5 years. It can take 10 years or more particularly for phase 3 trials and cohort studies Open a glossary item

. The research team may not start looking at the results until several years after the last person entered the trial.

When research teams analyse trial results, they look at what they call end points. How long it takes to get full results will depend on what the end point is.

Examples of end points are:

whether the cancer has got smaller
how long it is before the cancer starts to grow again
how long people live after treatment

Factors that affect trial results

How quickly the research team can get results will partly depend on:

the size of the trial and how long it takes to find enough people to take part
how long treatment lasts
the type of cancer

A trial looking at treatment for a rare cancer can often take longer to recruit people than one for a more common cancer.

The timing of results will also depend on the type of trial. Trials looking at cancer prevention or screening often take a long time to get results. It can take years to see a clear difference in the number of people in the different groups who go on to develop cancer.

How do I find results of a trial I have taken part?

If you have taken part in a clinical trial and want to know the results, the first thing to do is ask your doctor. They should be able to find the results for you if they are available. Or we may have a plain English summary of the results on our clinical trials database (see below).

The research team give a patient information sheet (PIS) to everyone who takes part. This PIS often says what they plan to do with the results of the trial.

Clinical trials results on our website

Since 2009, we have been writing trial results in plain English and putting them on our clinical trials database. You can use trials search page find them.

We include trials for all different cancers, funded by a variety of organisations. You can type in the name of the trial or treatment, and then select ‘results’ to find those with results summaries.

Unfortunately, some trials never produce results. If we know it’s unlikely that there will ever results, we say so on the database. This could be because the research team couldn’t find enough people to take part. Or it could be because the trial was stopped early for some reason. This means they don’t have enough information to get reliable results.

Sometimes results show that the new treatment didn’t work better than the existing treatment, or wasn’t as good as the research team had hoped. But even when a trial shows a treatment isn’t useful, it adds to our knowledge and understanding of cancer and how to treat it.

Other places to look for trial results

Clinical trial results are often published in specialist medical journals. There are many different journals published around the world, including:

You can use a search engine such as Google to look for articles and read summaries (abstracts). But you often can't see the full articles without a subscription to the journal.

Research papers are not written in plain English and often use many medical, scientific and statistical terms. They can be very difficult to understand if you are not used to reading this sort of information.

Sometimes the organisation or drug company running a trial will put trial results on their website. They may also send out a press release.

Researchers sometimes present the results of trials at a conference or meeting of cancer specialists. There are several in the UK and around the world. Some are for particular types of cancer, and some cover all types of cancer. They include:

European Society of Medical Oncology (ESMO) conferences in Europe
American Society of Clinical Oncology (ASCO) meetings and conferences in America

These presentations may also be available on the relevant website.

Systematic reviews

An organisation called The Cochrane Collaboration carries out systematic reviews. These are overviews of all the research into a specific issue.

The reviews look at the published results of all the trials that have investigated a particular treatment in a particular situation. They pull all that information together and draw conclusions.

They then write what is called a Cochrane Review and publish it on The Cochrane Library website.