A clinical trial protocol should state clearly what sort of results the researchers need to collect to decide which treatment is most effective and safest. These are called outcomes or end points.

It can sometimes take many years to get the results of particular trials.

If a trial is looking at how long people live after their cancer treatment, they need to be monitored for many years. So, researchers collect information for that time. The information is collected from the hospital or a patient's GP. Patients names are removed so individual people will not be identified in the study results.

The first outcome that researchers look for in a phase 2 trial is how effective the treatment has been in treating the cancer. If the cancer has stopped growing, shrunk or disappeared it is known as a response.

A complete response to treatment is defined as the disappearance of all of the detectable cancer for at least four weeks. Clearly this is a very good result, but even a complete response does not mean a cure. It takes several years with no sign of recurrence before the cancer can be thought of as cured.

A partial response is a decrease in cancer size by at least 30% for at least four weeks, without any signs of growth elsewhere in the body.

Duration of response is the period of time between a response to treatment and any recurrence of the cancer, or the cancer starting to grow again (if that happens).

Progression means that the size of the cancer has increased by more than 20%, or that new areas of cancer have appeared.

Time to progression is the length of time between starting treatment and the cancer progressing.

Stable disease means that a tumour is not getting any larger and the person's medical condition is stable.

Progression-free survival measures the length of time until the cancer starts to develop or get larger again.

Some trials look at longer-term outcomes of treatment. In a phase 3 trial, researchers are often looking at how long people live after the treatment (survival). Doctors and researchers monitor whether more patients are cured, or live longer, with the new treatment.

Disease-free survival is the length of time after treatment during which no disease is found.

Overall survival means how long patients live after they have entered a trial. This could be weeks, months or years, and takes account of all causes of death. Many cancer patients recover from their tumour and die from something quite different, years later. This will be recorded in the trial results. Some people will be alive five years after treatment, but may have a recurrence of their cancer. They are included in the overall survival statistics.

When cancer doctors talk about survival, they often measure this by looking at the number of people who have survived five or 10 years after their cancer was diagnosed. You may hear the terms 'five-year survival' or '10-year survival'. Many people will live for much longer than this, but these figures are often quoted. If someone has no sign of their cancer for five years after their treatment, it is unlikely to come back and they have a good chance of being cured.

The results of most clinical trials will be published in medical journals. However, a final report of a trial may not happen until many years after people were treated. Generally the best way to find out results is to ask your specialist.

Doctors will look at how many side effects the treatment causes and how mild or severe they are. You may be asked lots of questions about side effects and might be asked to fill in questionnaires about any side effects that you have.

Doctors and researchers can also look at how the treatment affects your life as a whole (quality of life), as well as its effect on your cancer. They can compare these effects with those of other types of treatment.