It can sometimes take many years to get the results of trials. This may be because many thousands of people need to take part to show a small but important difference between treatments.
If a trial is looking at how long people live after their cancer treatment, they need to be monitored for many years – often 5 years, but sometimes 10 years or more. Researchers continue to collect this information during this time. The information is collected from the hospital, national records or a patient’s GP. Patients’ names are removed so individual people will not be identified in the study results.