Cancer survival is the proportion of people alive at some point subsequent to the diagnosis of their cancer, or from some point post-diagnosis (conditional survival). It is represented as the probability of a group of people "surviving" a specified amount of time, such as three, five, or 20 years.

There are several measures of cancer survival which use different end points depending on the question of interest. This can be very confusing for those of us who are diagnosed with cancer.

Factors affecting survival statistics
Following are some of the factors that can affect the statistics for survival rates:

• Some may be interested in general cancer mortality rates, while others may want to know the mortality rates for specific cancers.

• Policy makers and others may be interested in death from cancer where the effects of death from other causes are removed, such as when comparing survival from cancer for different racial or ethnic groups with a very different other cause of death.

• Individuals may be interested in the both the probability of death from cancer and the probability of death from other causes each estimated in the presence of the other.

Important facts about survival
Unlike incidence or mortality statistics where the total population is included in the denominator, only people who are diagnosed with cancer are included in the survival calculations. In the past, there has been some confusion when people use the term mortality to mean (1-survival).

This is misleading, since mortality statistics include the entire population at risk, where survival (and 1-survival) only include people with cancer who are determined to be at risk. We use the term cumulative probability of death for (1-survival).

One problem in estimating long-term survival is that only those diagnosed a long time ago have enough follow-up to directly estimate these quantities. Thus, direct estimates of long-term survival may not be very relevant for people who are newly diagnosed, especially in cancer types where there have been dramatic improvements in survival.

Population-based survival derived from cancer registries differs in several important ways from survival derived in clinical trial settings. In a clinical trial, there is a detailed review of the medical record to ascertain the cause of death, whereas in population-based registry settings one must depend on death certificates, which have inherent inaccuracies.

See also

• Introduction
• Prevalence and prevention
• Causes and risk factors
• Detection and diagnosis
• Treatment options
• Prognosis
• Support