"The ratio of a cancer patient’s chances of surviving 5 years compared to that of an average cancer-free person of the same age and sex.
It compares the number of people who are still alive 5 years after their cancer was found to the survival of others the same age who don’t have cancer.
This helps correct for other causes of death and is a better way than survival rates alone to see the impact that cancer can have on survival.
Still, these survival rates cannot predict any one person’s outcome, which can be affected by many factors.
Even when survival rates are based on the most recent data available, they typically include information from patients treated several years earlier. Advances in treatment that have occurred since then might result in a better outlook for people who are newly diagnosed."