Participation rates in the organized colorectal cancer screening program, 2012–2013
Following a pilot phase in 23 metropolitan departments, organized colorectal cancer screening was expanded nationwide starting in 2008. Since 2010, this program has covered all French departments, with the exception of Mayotte (which became a French department on March 31, 2011). Screening is coordinated at the local level by departmental or interdepartmental management structures (a total of 89 management structures). Participation rates, calculated for the years 2012 and 2013 for all French departments, are presented in this document, along with exclusion rates and the percentages of positive tests.
Materials and Methods
The specifications for cancer screening programs published in the Official Journal on December 21, 2006 (Appendix to No. 295) stipulate that individuals aged 50 to 74 must be invited to undergo colorectal cancer screening every two years. The indicators are thus calculated over a two-year period, during which the entire population of a department is invited to participate in screening.
Calculation of the participation rate
The participation rate is the ratio of the number of people screened to the INSEE target population for screening (men and women aged 50 to 74), from which are subtracted those excluded from screening for medical reasons. It is defined as:
The number of people screened—that is, men and women aged 50 to 74 who underwent a screening test during the evaluation period (here, from January 1, 2012, to December 31, 2013)—and the number of people excluded from screening are provided by the administrative bodies via a standardized annual questionnaire.
At the national level and for the purpose of comparing departments, the denominators used to calculate participation rates are population data provided by INSEE (2007–2042 projections, central scenario), calculated identically across the entire country. From this population, individuals temporarily excluded from screening due to normal colonoscopy results within the past 5 years or permanently excluded for medical reasons are subtracted. The definition of medical exclusions is specified in the specifications (see above).
Calculation of the exclusion rate
The exclusion rate is the ratio of the number of people temporarily or permanently excluded from the organized colorectal cancer screening program (see above) to the INSEE target screening population (men and women aged 50 to 74).
The number of excluded individuals is reported by the administrative bodies via a standardized annual questionnaire.
Calculation of the percentage of positive tests
This is the ratio of the number of people with a positive test result to the number of people with a test result that can be analyzed by the screening test reading centers.
This information is provided by the administrative units via a standardized annual questionnaire.
Age groups
A breakdown into 5-year age groups was used.
The 50–54 age group includes individuals who turned 50 during the year under review, even if they had not yet reached that age at the time of screening; the 70–74 age group includes individuals who had turned 75 at the time of screening, generally due to a delay in taking the test after receiving the invitation sent up to age 74.
Standardization of indicators
Participation rates, exclusion rates, and the percentage of positive tests are calculated by department, by region, and for France. They are standardized by age and sex relative to the 2009 French population (INSEE projection 2007–2042, central scenario). This standardization allows, by applying the same age and sex structure (that of the 2009 French population) to geographic units, for comparing results between these units (departments or regions) and for studying changes over time in the various indicators examined.
Benchmarks
The European benchmark recommends a participation rate of the target population of at least 45% for the screening program to be cost-effective. This benchmark applies to all European countries that have implemented an organized screening program.
Results
Participation
During the 2012–2013 period, 18 million people aged 50 to 74 were invited to participate in the organized colorectal cancer screening program, and nearly 5 million underwent a test, representing a participation rate of 31% (see table). However, there was a slight decrease (-2.2%) compared to the 2011–2012 period. This rate is below the minimum acceptable European target of 45% participation, far behind the desirable rate of 65%.
Participation in the organized screening program increases with age and gender (see table). Women participate in the program more than men (32.8% versus 29.1%, respectively). The participation rate increases among women, rising from 30% for the 50–54 age group to nearly 37% for the 60–69 and 70–74 age groups, whereas among men, it rises from 25–26% for the 50–54 and 55–59 age groups, eventually approaching the participation rate of women of the same age in the 70–74 age group. Participation declines significantly starting in 2009–2010 among women under 70, while it remains generally stable for those over 70. This trend is also observed among men, though with a significant decline beginning in 2008–2010 for those aged 65–69 (see graphs). The increase in participation by age and sex observed at the national level is also seen in most regions, with the exception of Martinique, Réunion, and Languedoc-Roussillon, where it appears to decline with age for both men and women (see graphs).
Participation in the organized screening program varies considerably by region and department: see maps and tables (PDF and Excel formats), ranging from 7.3% in Corsica to 43.7% in Alsace. Rates are particularly low in Île-de-France (23.9%), French Guiana (17.3%), and Réunion (22.7%). Compared to the previous period, participation has increased significantly in the Guadeloupe region, rising from 27.5% to 33.1% (+20.4%), while a slight increase is observed, from 0.3% to 3%, in Lower and Upper Normandy, Brittany, Corsica, Limousin, Martinique, Nord-Pas-de-Calais, and Picardy. In contrast, regions such as Franche-Comté, Île-de-France, Midi-Pyrénées, and Provence-Alpes-Côte d'Azur recorded the sharpest declines (approximately 5–6%). The departments of Haut-Rhin and Saône-et-Loire have turnout rates above the recommended minimum threshold (47.0% and 50.1%, respectively), while 10 departments (Bas-Rhin, Côte-d'Or, Yonne, Ille-et-Vilaine, Cher, Indre-et-Loire, Loir-et-Cher, Ardennes, Maine-et-Loire, and Isère) have rates close to this threshold (40 to 45%). It should be noted, however, that this rate remains below 30% for 32 departments. Nevertheless, compared to 2011–2012, there has been a fairly variable increase in the participation rate across 22 departments, ranging from +0.3% for Ardèche and Loiret to +11.2% for Haute-Vienne. These geographic disparities can be partly explained by the departments’ earlier participation in the program. Indeed, participation remains higher in the pilot departments where the first campaigns began between 2002 and 2006 than in the departments that joined the program later (34% vs. 30%, respectively). However, changes in participation rates between the two campaigns—declining in some departments and regions and rising in others—suggest that other factors warrant investigation to explain these notable geographic differences.
Exclusions
The rate of temporary exclusion from screening due to normal colonoscopy results within the past 5 years or permanent exclusion for medical reasons is 12.3% (+4.2% compared to the 2011–2012 period), representing just over 2 million people excluded. It is higher among women (12.5%) than among men (12.1%). This exclusion rate increases significantly with age, from 6.8% among men aged 50–54 to 19.2% among those aged 70–74, while among women, it rises from 7.7% to 17.6% respectively for the same age groups (see table). There are significant regional disparities in exclusion rates, ranging from 4.3% in Corsica and French Guiana (up 13.2% and 30.3%, respectively, compared to 2011–2012) to nearly 19% in Deux-Sèvres and Loir-et-Cher (up 3.3% and 7.6%, respectively): (see maps and table). Exclusions (temporary or permanent) from the organized colorectal cancer screening program are more frequent in departments that have participated in the program for a longer period of time. They also depend on the efficiency of data collection regarding medical exclusions by the administrative bodies that organize screening at the departmental level.
Positive tests
During the period in question, nearly 5 million tests were performed, of which just over 105,000 were positive, representing 2.2%. The percentage of positive tests is higher among men (2.5%) than among women (1.9%), and it increases with age (see table). There is significant variation in the positive test rate across departments, ranging from 1% in Martinique to 5.3% in French Guiana and Hérault: see maps and table. Overall, the positive test rate fell from 2.4% to 2.2%, representing an 8.3% decrease compared to the previous period (2011–2012). This decrease is observed in three out of four departments and is particularly marked in the departments of Côte-d'Or (-44.2%) and Nièvre (-27.2%). The decrease in the positive test rate is consistent with the repeated screening campaigns, which make it possible to identify and exclude individuals with precancerous or cancerous colorectal lesions from the target screening population, and to refer them to their physician for more specific follow-up.
Conclusion
Five years after the nationwide rollout of the organized colorectal cancer screening program, participation is struggling to reach the minimum acceptable threshold of 45% recommended by the European Commission. Yet it is universally acknowledged that the effectiveness of a screening program depends on population uptake. Age, sex, marital status, and financial vulnerability are factors previously identified as independently associated with non-participation in the organized colorectal cancer screening program1. The role of certain psychological factors, such as the discomfort and embarrassment felt during a medical consultation, as well as fear and anxiety regarding colorectal cancer screening, could also hinder participation in the program2. Further efforts are needed to identify the profile of individuals who do not participate in the program, which would enable the adoption of an effective and targeted communication strategy for these individuals. The contribution of healthcare providers is undoubtedly a key factor in the success of this program. The program’s protocols are expected to change soon, as the Directorate General of Health has approved the replacement of guaiac tests (Hemoccult®) with new immunological tests using antibodies directed against human blood proteins. These immunological tests have higher sensitivity than the guaiac test for detecting advanced adenomas and cancers. The superior performance of the immunological test is likely to increase the confidence of general practitioners, which is known to be an important factor in encouraging patient adherence to the program. Furthermore, this change in testing could have a positive impact on screening participation due to greater public acceptance of this test, as its sample collection technique limits contact with stool compared to the guaiac test. The transition to the immunological test is scheduled for late 2014.
