Introduction 

The Canadian Cancer Registry at Statistics Canada provides a rich source of data on newly diagnosed cases of cancer in Canada. This data set is population based and national in scope. The wide variation in cancer rates, both regionally and over time, offer insight on how successful we have been in prevention and control of cancer and help assess the need for future programs.

In this exercise, data on female cancer have been provided in the attached tables, with the exception of regional breast cancer incidence, which is available online at Health Canada's Disease Surveillance web site. This web site provides examples of standard analyses and charts, as well as a glossary of terms.

The data provided in this exercise provide an opportunity to become familiar with statistical methods used in epidemiological research. Epidemiology is the study of patterns in disease. There are many methods available for analysis and presentation. The data set includes population, number of deaths attributed to breast cancer and the number of new cases of breast cancer by age group at the national level since 1969 and at the regional level since 1984.

Background

The main cancer control initiative has been breast cancer screening in women over 50 years of age, and in some provinces in women over 40 years of age where a family history of breast cancer exists. Initiation of a screening program will typically increase the number of new cases for a short period of time, then the number of new cases will level off, or even return to previous levels.

Data Sources

Cancer Incidence Data

Newly diagnosed cases of cancer are registered with the provincial and territorial cancer registries. Cancer incidence data were provided to Health Canada from the Canadian Cancer Registry, formerly the National Cancer Incidence Reporting System, at Statistics Canada. [1, 2]
 

Significant under-reporting of cancer cases occurred in the earlier years of the NCIRS. Under-reporting in Quebec prior to 1977 has been estimated at approximately 30%, followed by over-reporting, particularly in 1981 and 1982, with further details available in The Making of the Canadian Cancer Registry. [3]
 

Population Data
 

Statistics Canada conducts the National Population census every five years. The counts obtained from the census are slightly under estimated, so adjusted population estimates provided by Statistics Canada were used. Annual estimates for the intercensal years by 5-year age groups, sex, and census division are provided by Statistics Canada in publications [4, 5] and in electronic format.
 

Mortality Data
 

Cause-specific mortality statistics are collected by registrars of vital statistics in the provinces and territories of Canada and published annually by Statistics Canada. [6]
 

Notes

Small counts: To preserve the anonymity of individuals, Statistics Canada has rules concerning the reporting of small counts. In the attached Tables, counts of 1 or 2 have been grouped and appear as "<=2" but null counts are reported as "0".
 

Canadian Institute for Health Information: The Graduate Student Data Access Program (GSDAP) at the the Canadian Institute for Health Information (CIHI) may be of interest. This program provides quality health data to eligible graduate students at no cost. CIHI is a leader in developing Canada's health information system. In that role, CIHI is responsible for the provision of accurate and timely health data needed for policy making, health care management, and public awareness of the factors affecting good health. More detailed information about the GSDAP (including application forms) is available from their web site at www.cihi.ca/wedo/gsdap.htm.
 

What does "STD CANADA 1971" mean? If we want to compare rates over time, and the population is changing, then we use age standardized rates. That is, we use a weighted average of the age specific rates, and in this case, the table was produced using the 1971 population for weighting. You should be able to reproduce the age standardized rates from the counts and population given. The usual standard today is the 1991 population, and the use of the 1971 standard was an oversight, though it should not impact the analysis of the data.
 

Tables

• Table 1: Female Population for CANADA, YEAR 1969 TO 1996, STD CANADA 1971
• Table 2: Number of Cases of female breast cancer, for CANADA, YEAR of diagnosis 1969 TO 1994, STD CANADA 1971
• Table 3: INCIDENCE RATES /100,000 FOR CANADA, YEAR 1969 TO 1994, STD CANADA 1971
• Table 4: Number of deaths for female breast cancer, for CANADA, YEAR 1969 to 1996, STD CANADA 1971
• Table 5: MORTALITY RATES /100,000 FOR CANADA, YEAR 1969 TO 1996, STD CANADA 1971
• Table 6: Number of Deaths for Female Breast Cancer, for CANADA and PROVINCES, YEAR 1984 TO 1996, STD CANADA 1971
• Table 7: Female Population for CANADA and PROVINCES, YEAR 1984 to 1996
• Table 8: MORTALITY RATES /100,000 FOR CANADA AND PROVINCES, YEAR 1984 TO 1996, STD CANADA 1971
• Get all eight tables in an Excel 97/98 & 5.0/97 Workbook [138K binary file]
• Get all eight tables in an Excel 97/98 & 5.0/97 Workbook [138K binary file - by ftp]