Terms used in statistics 

Important concepts to understand cancer statistics


Number of expected new cases arising in a specified population within a given period.

(e.g. 5,400 new cases)


Number of deaths occurring in a specified population, within a given period.

(e.g. 1,600 deaths)

Both incidence and mortality can be expressed as total numbers (number of cases/deaths per year) or as rates/proportions (number of cases/deaths per 100,000 people, per year – when calculating rates it is customary to use “per 100,000 people”). 


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 pre-existing cases and is a function of both past incidence and survival.

Age standardized (or adjusted) rates

ASR = Age Standardized Rates

ASR is used so we can compare incidence/mortality between populations or regions that differ in respect to age. Some populations have more young people than others. This is important because age is a powerful factor in the risk of different cancers.

What ASR does is to adjust the data so we can see what it would look like if the population had a standard age structure. Once different populations are age standardized, we can compare them.

  • To find age standardized incidence or mortality rates, the population data is compared with a standard population, normally the World Standard Population. The incidence or mortality rate calculated in this way is called age-standardized incidence or mortality rate and is expressed by 100,000 people.   

(e.g. 60 new cases/ 100,000 people (ASR))

You can find all these concepts at IARC

See next section - Worldwide cancer statistics

next close
Know… the family risk consultation, it is recommended that people with a history of breast cancer in the family. How and where to access? (see)
Know… how to act to reduce the risk of colorectal cancer in the future. (see)
Know… the possible types of treatment for breast cancer, clinical trials and how to minimize side effects. (see)