UP TO WHAT AGE PROPOSE MASS SCREENING FOR COLORECTAL CANCER BY FAECAL OCCULT BLOOD TEST? ANALYSIS OF A COHORT IN A WELL-DEFINED POPULATION

Aims:

The question of continuing screening beyond 75 years is often asked. Our cohort is the only one concerned with a population screened after 75 years, allowing the determination of participation rate, the rate of positivity of the test and the effect of screening on CRC mortality and incidence.

Methods:

Our cohort, established in 1988 is composed of 4268 elderly people, aged 70 – 74 residing in a well-defined French area. A fecal occult blood test (Hémoccult) was proposed until 2002, and then a follow-up until 2009. In our population the invitation was continued to 82 – 86 years. The population studied is covered by the Burgundian register of Digestive cancers collecting data in the whole area population, screened and not screened.

The ratio of the number of observed deaths or incident cases and the number of expected deaths or incident cases determine the ratio of mortality (SMR) and incidence (SIR).

Results:

Participation rates remained higher than 40% during the 3 first campaigns and decreased less than 40% in the following 4. The participation rate decreases with the age, it remains above 40% up to 78 years and above 30% up to 80 years. The positivity rates of the test ranged from 1.7% to 3.0%. The incidence of cancers was in 1998 (during the screening campaign) of 2.3% for the screened population and 3.3% for the non-screened (P = 0.06); it was in 2009 (7 years after the last campaign of 3.3% and 4.8% respectively (P = 0,014). The stages of cancer were significantly less advanced in the screened population, than in the non-screened. This difference did not vary according to the number of participation per individual. SMR and SIR didn't differ significantly between participants and non-participants.

Conclusions:

The CRC mass-screening efficiency indicators remain good over 75 years and supports the extension to 78 – 80 years for mass screening.