[Mass screening for colorectal cancer in France. Experience in 165,000 people in the department of Calvados].

Objectives: Screening for colorectal cancer is a major public health problem in France as in most developed countries. Several controlled trials are on-going in Europe. The aim of the study was to determine requirements for success of mass-screening for colorectal cancer in France.

Methods: A mass-screening program has been conducted between April 1991 and June 1994 in the department of Calvados for 164,364 people aged 45-74 years. The screening test was first proposed by general practitioners and occupational doctors during appointments. Secondly, a postal invitation to obtain the test, free of charge, by doctor or chemist, was sent.

Results: Global participation rate was 43.4%; 40.2% of tests were distributed during the first phase, 47.1% during the second phase and 12.7% were distributed by a private health institute. Participation was higher for females (47.1%) than males (39.2%) and for urban districts (46.5%) than rural districts (24.4%). In case of positive test, colonoscopy has been more frequently achieved in urban districts and when test has been distributed by a physician. Positivity rate was 2.8%. Positive predictive value was 8.0% for a cancer and 13.5% for an adenoma larger than 1 cm. Because both positivity rate and positive predictive value were higher for males than females and increased with age, rate of cancer or large adenoma screened was almost three times higher for males than females and markedly increased with age.

Conclusions: In France, different recruitment methods have to be used to reach a satisfactory participation to a mass-screening campaign. Such a program requires involvement of general practitioners and close coordination between practitioners and health care insurance agencies.