Background. The purpose of the work was to evaluate the results of the second organizational round of the Slovenian national colorectal cancer screening programme, to assess the effects on the faecal immunochemical occult blood test results and the interval cancer analysis.
Patients and methods. The analysis included the population of Slovenian residents between 50 to 69 years of age, who were invited for screening between April 2011 and December 2012. The characteristics of the observed population and of stool samples were included in the analysis in order to analyse the effect on the screening test results and consequently the colonoscopy findings. Gender, age, years of schooling, the cancer site and cancer stage and the histological type were compared among interval cancers, screening cancers and cancers among non-responders. The proportional incidence method was used to calculate the screening test sensitivity.
Results. Higher shares of positive outcome of the faecal immunochemical occult blood test were more frequently shown among the observed males, aged over 54 years, with less than 10 years of schooling, participating for the first time in the screening programme and residing in the eastern part of Slovenia. The age of stool samples and ambient air temperature up to 25 °C were not significant for the outcome of the screening test. However, the ambient air temperature above 25 °C had the effect of lowering the proportion of positive results of the screening test. Amongst 502,488 people invited for screening, there were 493 cancers detected after the positive screening test, 79 interval cancers after the negative screening test and 395 cancers in non-responders. The proportion of interval cancers equalled 13.8%. Among all three observed cancer groups, cancers were more frequent in men and in persons aged 54+ years. Interval cancers were more frequent in the right hemicolon and in stage IV when compared to screen detected cancers. Screen detected cancers were more frequent in stage I and in the left hemicolon. Interval and screen detected cancers were more frequently detected in persons with 10 or more years of schooling when compared to cancers detected among non-responders. Cancers detected in non-responders were more frequent among people with lower education and in stage IV. There were differences between cancers detected groups according to the histological type of cancers diagnosed. Test sensitivity of the faecal immunochemical test was 88.45 %.
Conclusions. The outcomes of faecal immunochemical occult blood tests in Slovenian colorectal cancer screening are influenced by similar factors as in comparable foreign screening programmes. Besides higher age and male gender more positive results of the test were seen in persons with lower education, residing in the east of Slovenia, first screening episode. Ambient air temperature above 25 °C lowers the proportion of positive screening test results. More screen detected cancers in lower cancer stages prove the importance of organized cancer screening. Interval cancers after the negative faecal immunochemical occult blood test in Slovenian screening programme are detected in the expected proportions as in similar programmes. Test sensitivity is among the highest when compared to similar programmes and is accomplished by using two stool samples test kit.