To evaluate compliance by age, gender, and screening round in the population based Stockholm/Gotland colorectal cancer screening programme.
All individuals aged between 60 and 69 living in the counties of Stockholm and Gotland (Sweden) have, since 2008, successively been included in a colorectal cancer screening programme using biennial faecal occult blood tests (Hemoccult?). Personal invitations including test kits have been sent to home addresses, and individuals with a positive test result have been called to a defined clinic for an assessment colonoscopy. Descriptive statistics have been used to evaluate different aspects of compliance.
Over the five-year period 2008-2012, more than 200,000 individuals from nine different birth cohorts have been invited, with a compliance rate of approximately 60%, which increased by age, female gender, and subsequent screening round. In total, 4,300 individuals (2.1%) with positive tests were referred to assessment colonoscopy, where 213 colorectal cancers were diagnosed. The compliance with the follow-up colonoscopies varied by year, and ranged from 85.6-92.4%.
The strong organization of the programme contributed to a high compliance rate, that increased by screening round. The lower participation rate among men and among individuals at younger ages needs further attention.
Objective To evaluate interval cancers in the population-based colorectal cancer screening programme of Stockholm/Gotland, Sweden. Methods From 2008, individuals aged 60-69 were invited to colorectal cancer screening using biennial guaiac-based faecal occult blood test (Hemoccult®). Interval cancers, defined as colorectal cancer among participants not diagnosed by the screening programme but registered in the Swedish cancer register, were evaluated by cross-checking the screening histories for all cancers in the region 2008-2012. Results Of 203,848 individuals from nine different birth cohorts who participated (~60%), 4530 (2.2%) tested positive. All invited individuals were followed up for 24 months after invitation. The cancer register reported 557 colorectal cancer, 219 (39.3%) screen-detected cancers and 338 (60.7%) interval cancers, generating both test- and episode sensitivities of approximately 40% and an interval cancer-rate of 17.1/10,000 tests. Among individuals with positive tests without colorectal cancer diagnosed at work-up colonoscopy, 37 interval cancers (10.9%) occurred. There was statistically significant lower sensitivity in women, ranging 22.4-32.2%, compared with 43.2-52.0% in men. Age-group and tumour location were not strongly correlated to screen-detected cancer rates. The programme sensitivity increased by year (20.3-25.0%), with successively more colorectal cancers diagnosed within the expanding programme (11.6-16.2%). Conclusion Interval cancer is a quality indicator of a screening programme. As the interval cancer-rate determined in a well-organized population-based screening programme was actually higher than the screen-detected cancer rate, a change to a more sensitive screening test is indicated. The lower screen-detected cancers among women, and compliance and quality of work-up colonoscopies also need attention.