 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 (see agespecific rate and ASR below).
The rate provides an approximation of the average risk of developing a
cancer.

 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.

 Population at risk


The part of a population which is susceptible to develop a specific cancer. It
is defined on the basis of demographic data, such as place of residence, sex,
age group, etc. Years of risk duration are counted in personyears.

 Agespecific rate


The agespecific rate is calculated simply by dividing the number of new
cancers or cancer deaths observed in a given age category during a given time
period by the corresponding number of person years in the population at risk in
the same age category and time period. For cancer, the result is usually
expressed as an annual rate per 100,000 personyears. In ITACAN, fiveyear age
categories are used (highest group 85+).

 Crude rate


Data on incidence or mortality are often presented as rates. For a specific
tumour and population, a crude rate is calculated simply by dividing the number
of new cancers or cancer deaths observed during a given time period by the
corresponding number of person years in the population at risk. For cancer, the
result is usually expressed as an annual rate per 100,000 persons at risk.

 ASR (agestandardised rate)


An agestandardised rate (ASR) is a summary measure of the rate that a
population would have if it had a standard age structure. Standardisation is
necessary when comparing several populations that differ with respect to age
because age has such a powerful influence on the risk of cancer. The ASR is a
weighted mean of the agespecific rates; the weights are taken from population
distribution of the standard population. The most frequently used
standard population is the World Standard Population. The calculated
incidence or mortality rate is then called agestandardised incidence or
mortality rate (world). It is also expressed per 100000. The European standard
is often used and ITACAN gives the possibility of also choosing a Italian
standard where the agedistribution is from the Italian population in 2000.


Age distributions of the standard populations used for age
standardisation in ITACAN (per 100,000) 
Age group 
World
ASR (W) 
European
ASR (E) 
Italian
ASR (I) 
04 
12000 
8000 
5900 
59 
10000 
7000 
6600 
1014 
9000 
7000 
6200 
1519 
9000 
7000 
5800 
2024 
8000 
7000 
6100 
2529 
8000 
7000 
6800 
3034 
6000 
7000 
7300 
3539 
6000 
7000 
7300 
4044 
6000 
7000 
7000 
4549 
6000 
7000 
6900 
5054 
5000 
7000 
7400 
5559 
4000 
6000 
6100 
6064 
4000 
5000 
4800 
6569 
3000 
4000 
4100 
7074 
2000 
3000 
3900 
7579 
1000 
2000 
3500 
8084 
500 
1000 
2400 
85+ 
500 
1000 
1900 
Total 
100000 
100000 
100000 

 Cumulative risk


Cumulative incidence/mortality is the probability or risk of individuals getting/dying from the disease within a specified age interval within a time period. For cancer and from age 0, it is expressed as the number of new born children (out of 100) who would be expected to develop/die from a particular cancer before the age of 75, 80 or 85 if they had the rates of cancer observed in the period in the absence of competing causes. Like the age standardised rate, it permits comparisons between populations of different age structures.

 Standard error

The standard error of a rate is a measure of the sampling variability of the
rate.

 Confidence interval

A range of values that has a specified probability of containing the unknown
true rate or trend. The 95% (pvalue = .05) and 99% (pvalue = .01)
confidence intervals are the most commonly used.

 Estimated annual percentage change (EAPC)

The estimated annual percentage change is used to describe the magnitude of
change in the trend on fitting a simple regression model to the log of the ASR.
It is the average annual rate of change in the ASR over the time
period selected.
 Survival

Cancer survival statistics are typically expressed as the proportion of patients alive
at some point subsequent to the diagnosis of their cancer. Relative survival is an
estimate of the percentage of patients who would be expected to survive the effects of
their cancer. Observed survival is the actual percentage of patients still alive at some
specified time after diagnosis of cancer.
Survival of cancer patients in Italy
 Prevalence

Cancer prevalence is defined as the number or percent of people alive on a certain date in a
population who previously had a diagnosis of the disease. It includes new (incidence) and
preexisting cases, and is a function of both past incidence and survival.
Cancer prevalence in Italy
