Participants' characteristics in a French colorectal cancer mass screening campaign

Participation by the target population is clearly a key element in the success of mass screening programs for colorectal cancer. In France, involvement of general practitioners in test distribution is essential to reach a satisfactory participation rate, but other forms of recruitment also have to be organized. The aim of this study was to determine the influence of demographic characteristics such as sex, age, and place of residence on the participation rate in a French mass screening according to different recruitment methods.

The Hemoccult IIR test was proposed in three consecutive ways: spontaneously by general practitioners and occupational doctors during appointments (phase 1), by postal invitation (phase 2), and finally by direct mailing of the test (phase 3). The target population consisted of 11,947 people between 45 and 74 years of age, living in a district of the French county of Calvados, between March 1991 and April 1993.

The overall participation rate was 51.3%. Forty-nine percent of all the tests were done during phase 1, 31% during phase 2, and 20% during phase 3. The overall participation rate varied essentially according to the place of residence, from 65.5% in urban areas and 48.9% in intermediate areas to 27.7% in rural areas. The overall participation rate was also higher for females (57%) than for males (45%) and for those 60 years and older (53.9%) than for those below this age (49.2%). The proportion of tests done during phase 1 was lowest among the youngest and the oldest age groups (37.5% in the 45- to 49-year class and 45.2% in the 70- to 74-year class) and among people living in the rural environment (respectively 55.3%, 45.5%, and 35.9% in urban, intermediate, and rural areas).

This study shows that place of residence strongly influences the global participation rate in mass screening for colorectal cancer in France, whereas sex and age have little influence. Recruitment methods complementary to distribution by general practitioners must be organized, especially for the youngest and oldest age groups (45-49 years and 70-74 years) and above all for people living in rural areas. The social, cultural, and psychological reasons for these differences remain to be investigated, with the aim of adapting mass screening strategies to the different population groups.