1.Crude incidence rate (CR)
Crude incidence rate is the number of new cancer cases observed during a defined
period of population divided by the population at risk in the same period. It is expressed
per 100,000 population
2.Age-specific incidence rate
Age-specific incidence rate is the incidence rate in a specific-age group. The age specific
rates are calculated by dividing the number of cancer cases in each five years age and
sex structure of population in the age group multiplied by 100,000. The rates are expressed
per 100,000 populations
AR = Ni/Pi x 100,000
When Ni = Number of new cancer occurring in the age group
Pi = Population of the age group
3.Age-standardized incidence rate (ASR)
The age-standardized incidence rate is a summary measure of a rate that a population
will have if it has a standard age structure. It is calculated first by estimating the age -
specific incidence rates and applying these rates to the standard population. The world
standard population is used in this book. It is also expressed per 100,000 populations. Standardization
is necessary when comparing several populations that differ with respect to age because it has powerful influence on the risk of cancer |