INCIDENCE
Indicates the amount of new cases of cancer that occur in a defined population (ex. the residents in the city of Turin ) in a determined period (ex. year); such measure represents, thus, the risk to become in the population.
MORTALITY
Indicates the amount of deceased cases for a disease (ex. for the cancer of the lung, for all sites, etc.) in the observed population and in an interval time.
NUMBER OF CASES
Total number of registered cases for the period
N =  where ni =number of cases in the period by age group
i = index of five-year age group
AGE SPECIFIC RATES
Rates are annual, per 100,000 inhabitants. They result from the ratio between the number of cases in five-year age group and the resident population in the corresponding group.
Ri =  *100.000
where ni = number of cases by age groups
pi = population by age groups
Tables with age-specific rates can be consulted clicking on the buttons (men or women) in the last row of the boxes for incidence and mortality.
RATE PER CASE
The Rate per Case (RPC) for each age-group is the inverse of the population figure (1/population) for the sex and age-group, but multiplied by 100,000 and divided by the number of years included in the period of review. It is given in order to facilitate recovery of the actual number of cases contributing in the numerator to a given figure of incidence or mortality. For example, if we have a incidence rate of 12.3 for breast tumour in females aged 25-29, for which the RPC is 1.22698, it results from 10 cases in this category (12.3/1.22698). For larger rates, the calculation may be less accurate because the RPC is quoted only to a limited number of decimals.
CRUDE RATES
Rates are annual, per 100,000 inhabitants. The crude rate results from the ratio between the average annual number of cases registered in the period and the estimate of the resident population in the area of the Registry for that same period.
Crude R = 
where ni = number of cases by age groups
pi = population by age groups
STANDARDIZED RATES
Rates are annual, per 100,000 inhabitants, age-standardized by the direct method. When the disease is strongly correlated to age, such as in the case of cancer, the value of the crude rate is influenced by the true intensity of the phenomenon and by the proportion of elderly individuals in the observed population. Since the proportion of elderly subjects may vary to a great degree, comparisons between crude rates are biased. To solve this problem, the age standardization is used: this consists of applying the age specific rates of the observed population to the age distribution of a standard population (direct method). The result may be considered as a rate which would be obtained in the standard population if incidence (mortality) were that of the observed population. As standards, we applied the Italian population from the 1981 census, for comparing previously published data, the theoretical World population, as published in Cancer Incidence in Five Continents 1 .
Rstand = 
where psi = standard population by age groups
SURVIVAL
Survival measures time that elapsed from the date of the diagnosis to the date of recovery or death and expresses the proportion of incident cases that survive to successive anniversaries from diagnosis date. In the case of survival of incident cases occurred in a resident population of a defined geographic area, as survival measured by cancer registries, it can be said that it measures the effectiveness of the health system in the reference population. Ideally, one would only consider the clinical evolution of the disease, independently from other conditions. This problem is solved in clinical studies excluding those cases in which the cause of death is not from the disease evolution but it is attributable to other concurrent disease (specific survival). This is not after sensible in population studies, and it is a source of possible bias also in studies clinical. Therefore, a demographic correction is applied; it consistis of substracting the general mortality observed for all the causes in the general population in the study group to the mortality. Survival values (observed), after this correction are called relative survival and they make possible comparisons between populations and groups with different general mortality patterns show. Indicators in tables (observed and relative survival) percentage of persons still alive at 1, 5, 10 and 15 years from diagnosis. The first series of survival data presents results from the most recent cases, while the second series shows results from all cases registrated since 1985 (longer follow-up).
OBSERVED SURVIVAL
Observed survival (Sj) has been calculated according to the actuarial method as the product, until the follow up time (ex. to 1, 5, 10 or 15 years), of the survivals in single time intervals, that is :
where:
j = 1, 3, 5, 10, 15 years
 is the survival in the time interval (a month) estimated as:
where:
 is the conditional probability that a subject dies in the interval of
time i, since he/she survived until that time;
li' is the effective number of patients at risk in the time interval i and d i is the number of deaths in the same interval.
RELATIVE SURVIVAL
In order to eliminate the effect of competitive mortality, that is the mortality due to other causes, and, therefore, to estimate the effect of a single cancer on the patient survival, in used the relative survival (R j ), here calculated according to the Hakulinen method. It is relationship between the observed survival (S j ) and the expected survival if the studied group had experienced the same mortality for all causes as the general population (S j *), obviously tatting in to consideration that characteristics that can influence general mortality, such as sex, age, race, period of observation and geographic area.
Age-standardized relative survival is a method used to compare survivals with different composition by age. Patients were divided in age groups; at each age group was given a weight (according to “Corazziari et al, European Journal of Cancer, 2004”). Relative survival was then calculated for each age group and standardized survival is the result of the sum of the weighted age-specific relative survival.
PREVALENCE
The prevalence of cancer is the number of patients diagnosed with cancer present in the reference population. In the case of the Piedmont Cancer Registry, prevalence is the total number of patients with a given cancer diagnosed since the 1985 (year when cancer registration started in Turin population), and still alive. Prevalence indicators are expressed as number of cases per 100,000 in the reference population.
However, since other patients diagnosed before 1985, therefore not included in the registered series, could reasonably be still alive, they should be counted as prevalent cases. As a consequence, we estimated an “ overall ” prevalence that included also all those patients not observed in the patients set.
NOTES
Age-standardised relative survival
As comparison between different populations can be influenced by the different composition of their disease's age-at-onset, we also introduced such indicator to allow comparison with other published data (e.g. Rosso S. and the AIRTUM Working Group, “Italian cancer figures, Report 2007: Survival” , in Epidemiologia & Prevenzione, 31, suppl. 1, 2007).
Mortality statistics for Mesothelioma
The introduction of the tenth edition of the International Classification of Diseases (ICD X) allowed differentiating between pleural mesothelioma and other tumours occurring in the pleura. However, mortality is still coded with the old ninth version of ICD. As a consequence, incidence included all form of mesothelioma, also occurring outside pleura (mainly peritoneum, pericardium and testis vaginalis). At any rate, the misclassification is minimal, as the other forms of mesothelioma are very uncommon and rare (in the range of 32 mesotheliomas of the peritoneum and 2 mesotheliomas of the pericardium from 1985 to 2003).
Mortality statistics for Corpus and Cervix Uteri
As the amount of deaths for cancer of uterus unspecified is quite relevant, the specific mortality rates for Corpus and Cervix and their trends should be read with caution.
Survival trends for lip, tongue, mouth, oropharynx and oesophagus in women
Since these cancers are quite rare in women, the survival trends were unstable and therefore deleted from the graphical presentation.
Survival trends for melanoma in women
Survival of women with melanoma for the period 1985-1987 has been omitted in the graph as it was inconsistent, due to the lack of follow-up for some subjects.
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