The five-year survival rate is a type of survival rate for estimating the prognosis of a particular disease, normally calculated from the point of diagnosis.

Lead time bias Lead time bias happens when survival time appears longer because diagnosis was done earlier (for instance, by screening), irrespective of whether the patient lived longer. Lead time is duration of time between detection of a disease (by screenin ...

from earlier diagnosis can affect interpretation of the five-year survival rate. There are absolute and relative survival rates, but the latter are more useful and commonly used.

Relative and absolute rates

Five-year

relative survival Relative survival of a disease, in survival analysis, is calculated by dividing the overall survival after diagnosis by the survival as observed in a similar population not diagnosed with that disease. A similar population is composed of individuals ...

rates are more commonly cited in

cancer Cancer is a group of diseases involving abnormal cell growth with the potential to invade or spread to other parts of the body. These contrast with benign tumors, which do not spread. Possible signs and symptoms include a lump, abnormal b ...

statistics. Five-year absolute survival rates may sometimes also be cited. * Five-year ''absolute'' survival rates describe the percentage of patients alive five years after the disease is diagnosed. * Five-year ''relative'' survival rates describe the percentage of patients with a disease alive five years after the disease is diagnosed, divided by the percentage of the general population of corresponding sex and age alive after five years. Typically, cancer five-year relative survival rates are well below 100%, reflecting excess mortality among cancer patients compared to the general population. In contrast to five-year absolute survival rates, five-year relative survival rates may also equal or even exceed 100% if cancer patients have the same or even higher survival rates than the general population. The pattern may occur if cancer patients can generally be cured, or patients diagnosed with cancer have greater socioeconomic wealth or access to medical care than the general population. :

The fact that relative survival rates above 100% were estimated for some groups of patients appears
counterintuitive A paradox is a logically self-contradictory statement or a statement that runs contrary to one's expectation. It is a statement that, despite apparently valid reasoning from true premises, leads to a seemingly self-contradictory or a logically u ...
on first view. It is unlikely that occurrence of prostate cancer would increase chances of survival, compared to the general population. A more plausible explanation is that the pattern reflects a
selection effect Selection bias is the bias introduced by the selection of individuals, groups, or data for analysis in such a way that proper randomization is not achieved, thereby failing to ensure that the sample obtained is representative of the population int ...
of PSA screening, as screening tests tend to be used less often by
socially disadvantaged Social exclusion or social marginalisation is the social disadvantage and relegation to the fringe of society. It is a term that has been used widely in Europe and was first used in France in the late 20th century. It is used across discipline ...
population groups, who, in general, also have higher mortality.

Uses

Five-year survival rates can be used to compare the effectiveness of treatments. Use of five-year survival statistics is more useful in aggressive diseases that have a shorter life expectancy following diagnosis, such as

lung cancer Lung cancer, also known as lung carcinoma (since about 98–99% of all lung cancers are carcinomas), is a malignant lung tumor characterized by uncontrolled cell growth in tissues of the lung. Lung carcinomas derive from transformed, malign ...

, and less useful in cases with a long life expectancy, such as prostate cancer. Improvements in rates are sometimes attributed to improvements in diagnosis rather than to improvements in prognosis. To compare treatments independently from diagnostics, it may be better to consider survival from reaching a certain stage of the disease or its treatment. Analysis performed against the

Surveillance, Epidemiology, and End Results database The Surveillance, Epidemiology, and End Results (SEER) program of the National Cancer Institute (NCI) is a source of epidemiologic information on the incidence and survival rates of cancer in the United States. The Program SEER collects and pub ...

(SEER) facilitates calculation of five-year survival rates.

References

{{reflist, 30em Medical terminology Epidemiology