High sensitivity of five colorectal screening programmes with faecal immunochemical test in the Veneto Region, Italy.

OBJECTIVE: Although guaiac-based faecal occult blood test screening has been shown to be effective in reducing colorectal cancer (CRC) mortality, it has been criticised mostly for its low sensitivity. Italian CRC screening programmes are based on immunochemical tests (iFOBT). We collected and analysed the interval cancers (ICs) found by five screening programmes to estimate their sensitivity. METHODS: ICs were identified in subjects who had a negative result in a screening examination from 2002 to 2007 (N=267,789); data were linked with 2002-2008 hospital discharge records. Analysis was based on the follow up of 468,306 person-years. The proportional incidence-based sensitivity was estimated overall and by sex, age class, time since last negative iFOBT result, anatomical site, and history of screening (first or subsequent test). RESULTS: Overall, 126 ICs were identified, compared to 572 expected cancers. The proportional incidences were 15.3% and 31.0% in the first and the second interval-years, respectively, with an overall episode sensitivity of 78.0% (95% CI: 73.8 to 81.6). Sensitivity was higher for males than females (80.1% vs 74.8%); no differences were observed by age, anatomical site or between programmes. The test sensitivity of iFOBT was 82.1% (95% CI 78.1% to 85.3%). CONCLUSIONS: iFOBT-based screening programmes showed a high performance in terms of sensitivity as estimated through the IC rates. The screening schedule utilised in our programmes (single iFOBT, positivity threshold of 100 ng Hb/ml of sample solution, inter-screening interval of 2 years) shows low rates of missed cancers that are diagnosed during the interval. HDR are a convenient and reliable source of data for IC studies.

Quality control of mammography screening in the Veneto Region. Evaluation of four programs at a local health unit level--analysis of the frequency and diagnostic pattern of interval cancers.

AIMS AND BACKGROUND: Service mammography screening has been reported to have suboptimal performance compared to controlled trials. The aim of this study was to evaluate the sensitivity of the mammography screening program in four Local Health Units (ASL) and the possible causes of diagnostic error in cases further surfacing as interval cancers. MATERIAL AND METHODS: Interval cancers were identified by cross checking of screened women databases with hospital discharge records reporting breast cancer. Proportional interval cancer incidence (observed interval cancers/expected invasive cancers) was determined by matching the database of women screened during 1999-2002 to the hospital discharge records databases during 1999-2003. The ratio of observed interval cancer rate to underlying incidence was compared to international standards and with literature data. Screening mammograms reported as negative and followed by interval cancers were randomly mixed with true-negative controls, and the resulting set underwent blind review by an external radiologist who applied the conventional criteria recommended for the classification of the type of diagnostic error (occult, minimal signs, screening error). RESULTS: Matching of screening archives with the hospital discharge records databases allowed for the identification of 154 invasive interval cancers compared to 480 expected. The proportional observed/expected interval cancer incidence in the first and second year of the interval was 21% and 46%, respectively (ASL 1 = 14% or 38%, ASL 2 = 19% or 48%, ASL 3 = 30% or 53%, ASL 4 = 25% or 49%). Radiological review included 38 further interval cancer cases, identified after the time limits defined for proportional interval cancer incidence assessment, and could not include 18 interval cancers, not retrieved from ASL 4 archives: overall, 174 interval cancers were reviewed, of which 135 were classified as occult (77.3%) (ASL 1 = 83.3%, ASL 2 = 71.1%, ASL 3 = 78.6%, ASL 4 = 75%), 12 (6.9%) as minimal signs (ASL 1 = 6.6%, ASL 2 = 11.5%, ASL 3 = 2.4%, ASL 4 = 5%), and 27 (15.5%) as screening error (ASL 1 = 8.3%, ASL 2 = 17.3%, ASL 3 = 19.0%, ASL 4 = 25%). CONCLUSIONS: Observed proportional interval cancer incidence was lower than commonly reported for service screening programs and currently recommended (< 30% in the first, < 50% in the second year of the interval). The analysis of interval cancer causes showed a screening error rate below the maximum acceptable standard (< 20% of interval cancers should be classified as screening error) in three of four programs and in average figures. Substantial differences observed among single programs (one did not comply to recommended standards) suggest that space is available for the improvement of overall performance by optimizing program organization and by further training of radiologists. Overall, the analysis showed a good sensitivity of the screening program in the Veneto Region, although the performance was inferior to that of excellence centers, and further action to improve it is possible. Assessment and review of interval cancers is an early indicator of screening efficacy which has not yet been fully adopted in Italian screening programs. Although using hospital discharge records to identify interval cancers may be affected by limited errors, such a procedure is particularly convenient, as data from hospital discharge records are available much in advance compared to cancer registries and are the most reliable source of information for areas uncovered by a cancer registry. Hospital discharge records-based procedures for interval cancers assessment should be employed routinely in screening programs.