- 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 age-specific 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.
-
- Relative survival
-
-
Relative survival 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 sex, age and
calendar time at the time of diagnosis. It can be interpreted as the
probability of patient survival in the absence of other causes of death. It is
reported for 1 and 5 years following diagnosis, and also 10 years for breast
and prostate cancers. In NORDCAN the relative survival is age-standardised with the
International Cancer Survival Standards (ICSS).
| International Cancer Survival Standards (ICSS).
Three standard weight functions (W) for age-standardisation of relative survival as
used in Nordic cancer survival study 1964-2003. |
| Standard |
ICSS 1 |
ICSS 2 |
ICSS 3 |
| Characteristics |
Young adults |
Little age dependency |
Elderly |
| % of cancers |
2.5 |
10.2 |
87.3 |
| Cancer sites |
Testis, Hodgkin lymphoma |
Acute leukaemia |
Bone |
Melanoma, cervix, brain, thyroid, soft tissue |
Other sites and summary groups |
| Age groups and weights (W) in %
| Ages |
W |
Ages |
W |
Ages |
W |
Ages |
W |
Ages |
W |
| 0-29 |
31 |
0-29 |
31 |
0-29 |
7 |
|
| 30-39 |
21 |
| |
30-39 |
13 |
|
| 40-49 |
13 |
30-49 |
34 |
40-49 |
16 |
0-49 |
36 |
0-49 |
12 |
|
50-59 |
19 |
50-59 |
17 |
| 50-69 |
20 |
50-69 |
20 |
50-69 |
41 |
60-69 |
22 |
60-69 |
27 |
|
70-79 |
10 |
|
70-79 |
16 |
70-79 |
29 |
| 70-89 |
15 |
80-89 |
5 |
70-89 |
23 |
80-89 |
7 |
80-89 |
15 |
| 90+ |
0 |
90+ |
0 |
90+ |
0 |
90+ |
0 |
90+ |
0 |
-
- 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. For persons with
more than one cancer the person is included as a prevalent cancer in each
cancer site from the time of diagnosis of that cancer and in the 'All cancer
but non-melanoma skin' group from the first diagnosis.
Total prevalence represents the number of previously diagnosed
persons alive at the end of a year 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. Prevalence of cancers based on cases diagnosed within one,
three, five, ten and all years are presented in NORDCAN, as they are
likely to be of relevance to the different stages of cancer therapy, namely,
initial treatment (one year), clinical follow-up (three years) and cure (five
years). Patients who are still alive five years after diagnosis are usually
considered cured since the death rates of such patients are similar to those in
the general population. There are exceptions, particularly breast cancer. Prevalence is available both as numbers and as proportions per 100.000 persons. Age-standardised prevalence proportions are available for comparing countries, offering a choice of World(W), European(E) and Nordic(N) age-standards as for incidence and mortality.
-
- 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 person-years.
-
- Age-specific rate
-
-
The age-specific 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 person-years. In NORDCAN, five-year 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 (age-standardised rate)
-
-
An age-standardised 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 age-specific 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 age-standardised incidence or
mortality rate (world). It is also expressed per 100000. The European standard
is often used and NORDCAN gives the possibility of also choosing a Nordic
standard where the age-distribution is from the NORDCAN population in 2000.
-
-
| Age distributions of the standard populations used for age
standardisation in NORDCAN (per 100,000) |
| Age group |
World
ASR (W) |
European
ASR (E) |
Nordic
ASR (N) |
| 0-4 |
12000 |
8000 |
5900 |
| 5-9 |
10000 |
7000 |
6600 |
| 10-14 |
9000 |
7000 |
6200 |
| 15-19 |
9000 |
7000 |
5800 |
| 20-24 |
8000 |
7000 |
6100 |
| 25-29 |
8000 |
7000 |
6800 |
| 30-34 |
6000 |
7000 |
7300 |
| 35-39 |
6000 |
7000 |
7300 |
| 40-44 |
6000 |
7000 |
7000 |
| 45-49 |
6000 |
7000 |
6900 |
| 50-54 |
5000 |
7000 |
7400 |
| 55-59 |
4000 |
6000 |
6100 |
| 60-64 |
4000 |
5000 |
4800 |
| 65-69 |
3000 |
4000 |
4100 |
| 70-74 |
2000 |
3000 |
3900 |
| 75-79 |
1000 |
2000 |
3500 |
| 80-84 |
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 or (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% (p-value = .05) and 99% (p-value = .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.
|