Technical Report for the National Committee on Colorectal Cancer Screening

Introduction

In 1998, following discussions with experts and stakeholders in Canada, Health Canada established a National Committee to examine the implementation of population-based colorectal cancer (CRC) screening in Canada. The Committee's mandate was to determine the issues of national importance and explore their scope, and on the basis of this information to develop recommendations with respect to population-based colorectal cancer screening in Canada.

This document presents the information that was integral to the development of the Final Recommendations by the National Committee according to agreed upon criteria.

Colorectal Cancer Screening

CRC is the third most commonly diagnosed cancer in Canada after prostate and lung cancer in men, and breast and lung cancer in women. It was estimated that in 2001, there would be 17,200 new cases and 6,400 deaths from the disease in Canada.¹ Although CRC incidence and mortality rates among men and women are declining, control strategies for this cancer are nonetheless important given that CRC continues to be an important cause of morbidity and mortality.

Evidence is limited with respect to the effectiveness and practicality of some strategies for the primary prevention of cancer. Attention has been focused, as a result, on opportunities for secondary prevention (i.e., screening), which aims to detect the disease at an early, treatable stage and thus to reduce rates of morbidity and mortality.²

Several randomized controlled trials (RCTs) have examined the efficacy of CRC screening using fecal occult blood testing.^3-6 While these studies have differed somewhat in the populations recruited and in the testing protocols, all have shown a benefit from screening, with a reduction in CRC mortality of 15% to 33% depending on the screening interval.^3-6

The evidence of efficacy for screening in individuals is generally taken to be necessary but not sufficient to recommend population-based screening. Other countries have reviewed this evidence as well as the other factors that need to be considered for such screening and have come to differing conclusions. To date, no country has decided to establish national organized screening programs for colorectal cancer; however, large-scale, population screening programs with funding from government health agencies, are in place in Germany, Japan, and the USA with the implementation of others scheduled for Australia and Israel.⁷ Pilot or feasibility studies have been recommended in Australia² and France^8,9 and have been proposed and established in Great Britain^10,11 to assess the benefits of screening a large scale population. Some jurisdictions in Israel, Australia, Italy, France, and China and some Health Maintenance Organizations in the US are conducting or have conducted local or regional programs/studies using various FOB screening tests.^12-17

New Zealand has decided not to recommend a population-based screening program for CRC using the fecal occult blood test, given the modest potential benefit, the small but nonetheless real potential for harm, and the substantial commitment of health care resources that would be required.¹⁸

In Canada, some provinces have been considering the impact of implementing CRC screening. It was felt that a national committee might be able to provide some guidance on assessing population-based CRC screening.

The National Committee on Colorectal Cancer Screening

The National Committee on Colorectal Cancer Screening was chaired by Dr. Heather Bryant, Director, Epidemiology, Prevention and Screening and Vice-President of the Alberta Cancer Board; it was supported by Health Canada. Membership included nominees from the provincial cancer agencies/foundations; the Canadian Cancer Society/National Cancer Institute of Canada; professional and non-professional organizations; consumer groups; and Health Canada. The list of members of the National Committee and terms of reference for the group are presented in Appendix A.

The National Committee met six times over the course of 2 years (1998 to 2000) to explore the impact, feasibility and associated issues surrounding population-based CRC screening in Canada.

The mandate of the National Committee was not to address screening at the individual (clinical) level but, rather, to assess the impact and feasibility of population-based screening for average-risk individuals. The distinction between screening at the individual versus the population level should be emphasized. Population-based screening openly acknowledges that, in order to achieve the desired reductions in mortality, a substantial proportion of the population will need to be screened. Cost-effectiveness is closely examined when population-based screening is being considered. Screening on an ad hoc basis, as could occur if the Preventive Services Task Force recommendations were accepted and put into practice, would incur similar unit costs for individuals but would not be subject to the same scrutiny with regard to false positive rates, appropriateness of the screened population, and other measures that are important in population-based screening. This report takes a population-based approach, on the assumption that Canadians would expect a population-based benefit and that, in a publicly funded health system, appropriate monitoring to ensure maximal cost-efficiencies would be preferable to a non-organized approach.

Other Cancer Screening in Canada

In Canada, programs for organized breast cancer screening began in British Columbia in 1988 and have expanded to include all provinces, the Yukon, and the Northwest Territories. Although programs have grown over the last decade, provincial/territorial participation rates in 1997 and 1998 ranged from 11.5% to 54.7% for women 50 to 69 years of age, well below the rate of 70% targeted by screening programs in other countries.¹⁹ The primary reason for the apparently low uptake, however, is the presence of opportunistic screening in several provinces. There is little information on screening that occurs outside of organized programs, but results from the National Population Health Survey (self-reported data) have shown substantial increases in mammographic screening in the target population. Furthermore, the rate of increase in uptake has been faster in provinces where there are organized screening programs.²⁰

The need for comprehensive programs for cervical cancer screening was explored by the Conference of Deputy Ministers in 1973 and the "Walton Report" was published on behalf of the Task Force on Cervical Cancer Screening in 1976. Recognizing that cervical cancer was potentially preventable with early detection and screening, the Task Force recommended that health authorities support the development of screening programs for cervical cancer and that the participation of all women should be encouraged.²¹ In 1980, the Walton Task Force was reconvened in response to the lack of implementation of these recommendations and to concerns about changes in sociosexual patterns.²² Currently, British Columbia and Nova Scotia have well established, organized programs for cervical cancer screening. Recently, Alberta, Manitoba, Ontario, and Prince Edward Island launched programs that encourage the participation of all eligible women. Provincial programs target all women of a specified age range (usually 18-69) in their population however at the present time, no province encompasses population-based recruitment.²³

Relevant Criteria for Population-based CRC Screening in Canada

According to Gordis, early detection of disease means "detecting a disease at an earlier stage than would usually occur in standard medical practice".²⁴ This implies detection at a pre-symptomatic stage, at which point the patient has no clinical complaint (no symptoms or signs) and, therefore, no reason to seek medical care for a condition.

The National Committee reviewed and assessed the appropriateness of the World Health Organization (WHO) screening criteria, developed by Wilson and Jungner in 1968 ²⁵ from a population-based perspective, and modified them in order to reflect the Canadian context and to help fulfil the Committee's mandate. These criteria are presented in Table 1. The information that would be necessary to support each of the criteria was identified: sources of Canadian data were located, information gaps were noted, emerging questions and issues were identified. The impact of population-based screening on mortality, the potential risk/benefit of population-based screening, and cost/resource implications were estimated using statistical modelling, through a collaboration between Statistics Canada and Health Canada.

Although the mandate of the National Committee was not specifically to address primary prevention of CRC, the Committee acknowledged that primary prevention would be complementary to any efforts towards its early detection. A short summary of the extensive literature surrounding primary prevention of CRC, as of July 2001, can be found in Appendix B.

When seeking recommendations for clinical practice, Canadian physicians can refer to the recommendations of the Canadian Task Force on Preventive Health Care (formerly the Canadian Task Force on the Periodic Health Examination). The recommendations of this group are aimed at guiding the use of preventive clinical practices for clinicians. (These recommendations were published in July 2001²⁶, after the last meeting of the National Committee, which took place in November 2000.) The evidence from RCTs on screening for CRC using the fecal occult blood test (FOBT) led the Canadian Preventive Services Task Force to upgrade fecal occult testing to an "A" recommendation, indicating that there is strong evidence to support the use of the test to prevent CRC. Groups at high risk of CRC are also addressed by the Canadian Task Force on Preventive Health Care.

This document describes the criteria chosen by the National Committee and the supporting information/evidence. Canadian data were used as much as possible when available and deemed to be valid.

CRC is an area of research that is rapidly evolving and changing. This document presents information that was available up to November 2000, when the National Committee met for the last time. The authors acknowledge that since that time there have been more studies and information/evidence, which are not considered in this report.

Criterion	Canadian Adaptation of the Principles of Early Disease Detection		Principles of Early Disease Detection*
1	• The condition should be an important health problem.		•The condition sought should be an important health problem.
2	• The natural history of the condition, including development from latent to declared disease, must be understood. There should be a recognizable latent (asymptomatic) period or early symptomatic stage.		• The natural history of the condition, including development from latent to declared disease, should be adequately understood. • There should be a recognizable latent or early symptomatic stage.
3	• There should be a suitable screening test or examination.		• There should be a suitable test or examination.
4	• The overall benefit of the screening program should outweigh the potential harms from its application.
5	• The test (inclusive of screening and diagnosis) and the screening program should be acceptable to the population.		• The test should be acceptable to the population.
6	• Evidence-based recommendations should be available regarding who should be offered further diagnostic investigation and/or treatment and the choices available to them.		• There should be an agreed policy on whom to treat as patients.
7	• Treatment or intervention that improves survival or quality of life (compared with not screening) should be available for patients with recognized disease.		• There should be an accepted treatment for patients with recognized disease
8	• Adequate staffing and facilities for recruitment, testing, diagnosis and follow-up, treatment, and program management should be available.		• Facilities for diagnosis and treatment should be available.
9	• The resources allocated to the screening program (including testing, diagnosis and treatment of patients diagnosed) should be economically balanced in relation to other health care priorities.		• The cost of case-finding (including diagnosis and treatment of patients diagnosed) should be economically balanced in relation to possible expenditure on medical care as a whole. • Case-finding should be a continuing process and not a "once and for all" project.

^*  Wilson JMG, Jungner G. Principles and practice of screening for disease. World Health Organization, 1968.

Technical Report of the
National Committee on
Colorectal Cancer Screening
May 2002

136 pages (1,447 KB) in PDF format 

[Population-based Colorectal Cancer Screening]