Coverage and performance of colorectal cancer screening with the faecal occult blood test in Finland.

INTRODUCTION: Mortality from colorectal cancer has been shown to decrease by repeated screening using faecal occult blood (FOB) testing in randomized screening trials. This report presents coverage and performance of organized screening among the general population in Finland. METHODS: In 2004-2007, people aged 60-69 years were randomized into biennial screening and control arms. The screening test was a guaiac-based FOB test (Hemoccult) with dietary restriction and three test cards for six consecutive samples. Test positives were referred for full colonoscopy. The programme was launched in 2004 and subsequently it expanded over regions and age-cohorts. RESULTS: In 2007, the programme covered one-third of the target population and 74,592 people had been invited for screening, of them 26,866 for the second round. Uptakes for the first and second rounds, respectively, were 62% and 68% in men and 77% and 80% in women. The proportion of test positives increased from 2.4% to 2.9% from the first to the second round and the positive predictive value for cancers decreased from 7.5% to 4.3%. CONCLUSIONS: By 2007, organized colorectal cancer screening covered one-third of the target population in Finland. Implementation of screening measured with response rate was successful and met the criteria for a public health programme, but performance in terms of positive predictive value needs monitoring.

Use of faecal markers in screening for colorectal neoplasia: a European group on tumor markers position paper.

Several randomized controlled trials have shown that population-based screening using faecal occult blood testing (FOBT) can reduce mortality from colorectal neoplasia. Based on this evidence, a number of countries have introduced screening for colorectal cancer (CRC) and high-risk adenoma and many others are considering its introduction. The aim of this article is to critically review the current status of faecal markers as population-based screening tests for these neoplasia. Most of the available faecal tests involve the measurement of either occult blood or a panel of DNA markers. Occult blood may be measured using either the guaiac faecal occult blood test (gFOBT) or a faecal immunochemical test (iFOBT). Although iFOBT may require a greater initial investment, they have several advantages over gFOBT, including greater analytical sensitivity and specificity. Their use results in improved clinical performance and higher uptake rates. Importantly for population screening, some of the iFOBTs can be automated and provide an adjustable cutoff for faecal haemoglobin concentration. However, samples for iFOBT, may be less stable after collection than for gFOBT. For new centres undertaking FOBT for colorectal neoplasia, the European Group on Tumour Markers recommends use of a quantitative iFOBT with an adjustable cutoff point and high throughput analysis. All participants with positive FOBT results should be offered colonoscopy. The panel recommends further research into increasing the stability of iFOBT and the development of improved and affordable DNA and proteomic-based tests, which reduce current false negative rates, simplify sample transport and enable automated analysis.

Test, episode, and programme sensitivities of screening for colorectal cancer as a public health policy in Finland: experimental design.

OBJECTIVES: To report the sensitivities of the faecal occult blood test, screening episode, and screening programme for colorectal cancer and the benefits of applying a randomised design at the implementation phase of a new public health policy. DESIGN: Experimental design incorporated in public health evaluation using randomisation at individual level in the target population. SETTING: 161 of the 431 Finnish municipalities in 2004-6. PARTICIPANTS: 106 000 adults randomised to screening or control arms. In total, 52 998 adults aged 60-64 in the screening arm received faecal occult blood test kits. MAIN OUTCOME MEASURES: Test, episode, and programme sensitivities estimated by the incidence method and corrected for selective attendance and overdiagnosis. RESULTS: The response for screening was high overall (70.8%), and significantly better in women (78.1%) than in men (63.3%). The incidence of cancer in the controls was somewhat higher in men than in women (103 v 93 per 100 000 person years), which was not true for interval cancers (42 v 49 per 100 000 person years). The sensitivity of the faecal occult blood test was 54.6%. Only a few interval cancers were detected among those with positive test results, hence the episode sensitivity of 51.3% was close to the test sensitivity. At the population level the sensitivity of the programme was 37.5%. CONCLUSIONS: Although relatively low, the sensitivity of screening for colorectal cancer with the faecal occult blood test in Finland was adequate. An experimental design is a prerequisite for evaluation of such a screening programme because the effectiveness of preventing deaths is likely to be small and results may otherwise remain inconclusive. Thus, screening for colorectal cancer using any primary test modality should be launched in a public health programme with randomisation of the target population at the implementation phase.

Limits of preservation of samples for urine strip tests and particle counting.

BACKGROUND: Preservation of urine samples is important for centralised laboratory services with automated instruments. METHODS: A multicentre evaluation was carried out to assess preservative tubes from BD Diagnostics-Preanalytical Systems and from Greiner Bio-One for test strip reading (documented at the level of remission values), for particle counting by flow cytometers (UF-100) and for visual microscopy. Failures were expressed as percentages of originally positive samples beyond a two-fold change (+100% or -50%) from the original values. RESULTS: The preservative-containing BD Plus C&S plastic, BD Plus UAP and Greiner Stabilur tubes succeeded in preservation of test strip results for 6-24 h (exceptions were glucose and nitrite tests). Greiner boric acid tube showed false negative results in leukocyte, protein and ketone strip tests immediately after adding the preservative. Urine red blood cell counts (with Sysmex UF-100) were preserved for 5 h in BD Plus C&S plastic and Greiner Stabilur tubes (Greiner tubes having clearly larger preservative-related background). Bacteria or white blood cell counting succeeded in BD Plus C&S plastic tubes for 5 or 24 h, respectively, but up to 72 h in Greiner Stabilur tubes. In visual microscopy, the Greiner Stabilur tube was slightly better than the BD Plus C&S plastic tube. CONCLUSIONS: Urine specimens can be transported at +20 degrees C on the day of collection if preserved properly. Longer delays need careful planning with current preservatives. Flow cytometry with UF-100 is sensitive to non-dissolved preservative remnants.