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Cancer Registry
The cancer registry has a pivotal role in cancer control. Its primary function is the maintenance of a file or register of all cancer cases occurring in a defined population in which the personal particulars of cancer patients and the clinical and pathological characteristics of the cancers, collected continuously and systematically from various data sources, are documented. The registry analyses and interprets such data periodically and provides information on the incidence and characteristics of specific cancers in various segments of the resident population and on temporal variations in incidence. Such information is the primary resource not only for epidemiological research on cancer determinants but also for planning and evaluating health services for the prevention, diagnosis and treatment of the disease. (Cancer Registration: Principles and Methods IARC Scientific Publication No. 95).

Incidence
Incidence is the number of new cases arising in a given period in a specified population. This information is collected routinely by cancer registries. It can be expressed as an absolute number of cases per year or as a rate per 100,000 persons per year.

Mortality
Mortality is the number of deaths occurring in a given period in a specified population. It can be expressed as an absolute number of deaths per year or as a rate per 100,000 persons per year. Mortality data are provided by national statistical offices.

Survival
It is defined as the probability of survival, expressed as time elapsed since diagnosis (1,3 5-year survival). This observed survival probability is influenced by mortality both from cancer of interest and from other causes. For this reason, relative survival is usually calculated. It is defined as the ratio of the observed survival in the group of patients to the survival expected in a group of people in the general population, who are similar to the patients with respect to all possible factors affecting survival at the beginning of the follow-up period, except for the disease of interest.

Prevalence
The prevalence of a particular cancer can be defined as the number of persons in a defined population who have been diagnosed with that type of cancer, and who are still alive at the end of a given year, the survivors. Complete prevalence represents the number of persons alive on a certain day who previously had a diagnosis of the disease, regardless of how long ago the diagnosis was, or if the patient is still under treatment or is considered cured. Partial prevalence , which limits the number of patients to those diagnosed during a fixed time in the past, is a particularly useful measure of cancer burden.

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