Understanding clinical trial results

It may take many years to get the results of a trial. This is because hundreds and sometimes thousands of people need to take part in a trial to show the difference between treatments.

Sometimes trials look at how much longer people live after treatment (survival). For these trials, researchers need to monitor people for 5 years, 10 years or even longer. They continue to collect this information during this time.

The information is collected from the hospital, GPs’ records or national records. They remove names, so individual people are never identified in the study results.

Understanding trial results

Researchers need to collect information to help them decide which treatment is safest and most effective. Researchers call this the outcome or end-point of the trial.

In a phase 2 trial, the first outcome that researchers look for is how effective the treatment has been in treating the cancer.

When most cancers stop growing, shrink or disappear, doctors call this a response. Doctors use different words to describe your response to treatment:

  • A complete response means all signs of the cancer that can be seen through tests have disappeared for at least 4 weeks.
  • A partial response means the cancer has shrunk by at least 30% for at least 4 weeks. There are no signs that it has grown anywhere else in the body.
  • Stable disease means the cancer has shrunk by less than 30%. There are no signs that it has grown anywhere else in the body.

A complete response is a good result, but it does not always mean a cure. It takes several years with no signs of the cancer returning (recurrence) before doctors consider it cured. It also depends on the type of cancer.

Finding out results

Researchers publish the results of most clinical trials in medical journals. But they may not publish the final report until years after giving the treatment. Sometimes results are reported in newspapers or discussed on TV or radio. This is usually after the results have been presented at a medical conference or published in medical journals.

Generally, the best way to find out results is to ask your specialist. But nowadays, more patients are being contacted directly when results of trials are available.

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