A partial response means a decrease in cancer size by at least half for at least four weeks, without any signs of growth elsewhere in the body. Progression means that the cancer size has increased by more than a quarter or that new areas of cancer have appeared. Time to progression is the length of time between entering the trial and the cancer progressing. Having measured the immediate response to treatment, researchers then start to look at more long-term end points. 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. Five and 10 year survival figures are common end points. They refer to the proportion of people who have survived 5 or 10 years after their cancer was diagnosed. Many will have lived much longer but, for some cancers, to survive this long with no sign of cancer is a good indication of cure. This is why these figures are often quoted.