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Screening strategies

Screening strategies. Tryggvi Björn Stefánsson Dept of Surgery Landspitali University Hospital. WHO criteria for population screening. The condition should be an important health problem. Treatment must exist. Latent or early symptomatic stage. Target population.

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Screening strategies

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  1. Screening strategies Tryggvi Björn Stefánsson Dept of Surgery Landspitali University Hospital

  2. WHO criteria for population screening • The condition should be an important health problem. • Treatment must exist. • Latent or early symptomatic stage. • Target population. • Test validated and acceptable • Scientific evidence for program effectiveness (RCT) • Training • Quality control Wilson and Jungner 1968 and Anne Andermann, Ingeborg Blancquaert, Sylvie Beauchamp, Véronique Déry 2008

  3. The Condition. Sojourn time Lead time Survival time 5-10 years 5-10 years Adenomatous Polyp CRCancer Symptoms Death 55 – 65 years 65 – 75 years Screening Screening

  4. Goals of CRC screening • Detect cancer at an early, curable stage. • Detect and remove adenomatous polyps.

  5. The Tests • 1) tests that primarily detect Cancer • gFOBT (guaiac-based fecal occult blood testing) • FIT (immunochemical-based FOBT) • sDNA (testing stool for exfoliated DNA) • 2) tests that can detect cancer and advanced lesions. • Double-contrast barium enema. • CT colonography. • Flexible sigmoidoscopy. • Colonoscopy.

  6. gFOBT vs FIT gFOBT FIT • Guiac detects peroxidase activity. • Heme • Plant peroxidases. • Red meat • Vit C • Bleeding from all GI tract • Special diet for 3 days • 3 samples • Globin. • Human blood. • Detects only occult bleeding from the colon. • No dietary interference. • 1 sample

  7. gFOBT Finland • Sensitivity for CRC: 55%* • Specificity : 98%* • Compliance: 71%* (23%-78%) • FOBT+ 2,1%* • Cancer in FOBT+ 8,2%* • Highest sensitivity (50%) in the stage of clinical diagnosis** • Very low sensitivity for precancerous lesions *H. Paimela et al. BJS 2010 ** Iris Lansdorp-Vogelaar, Cancer, 2009

  8. FIT • FIT is superior to gFOBT in terms of compliance and detection of CRC and advanced adenomas. Rabeneck L et al. Can J Gastroenterol 2012. • FIT+ 5,2% • Cancer in FOBT+ 6% • High positivity rate, High sensitivity, low specificity . J. Faivre, European Journal of Cancer, 2012.

  9. sDNA • Stool DNA test: Finds DNA markers for precancerous lesions and cancers. • Multicentered study from the Mayo clinic: • Sensitivity for CRC 85% Sensitivity for adenomas (≥1 cm) 54% • Specificity 90% • Still research • Expensive Ahlquist DA et al, Gastroenterology. 2012 Feb

  10. DCBE • 48% sensitivity to detect polyps (> 1cm)compared to colonoscopy. Winawer, Gastroenterology, 2000. • Alternative for those who cannot undergo colonoscopy.

  11. DCBE vs CT colonography • CT colonography: Lower radiation dose than DCBE. Neri et al Abd Imaging 2010. Sensitivity Specificity • CT colonogr 83% 86% • DCBE 60% 97% Johnson CD clinical gastroenterol and hepatol 2004 • CTC can be done without cleansing (stool tagging)

  12. CT Colonography Polyps > 10mm Sensitivity 93% Specificity 97% Polyps 6-10mm Sensitivity 86% Specificity 86% Cancer Sensitivity 95,9% Halligan S et al Radiology 2005

  13. Sigmoideoscopy • Investigates 60 cm. Removal of all polyps within 60 cm. • Followed by colonoscopy in case of advanced lesions. • Sensitivity and specificity for polyps and cancer is high. • Sensitivity for advanced lesions and CRC in the whole colon : 60-70% of the sensitivity of a colonoscopy. Lieberman NEJM 2000

  14. Colonoscopy • Investigates all colon and removal of all polyps • The main screening method today • Required for confirmation of positive findings from other tests. • Gold standard for assessment of the efficacy of other screening methods.

  15. Effectivity of Screening Programs Incidence Mortality • gFOBT 0 15% * (25%*) • FIT ? ? • sDNA ? ? • DCBE ? ? • CT colonography ? ? • Sigmoidoscopy 21% (33%) 33% (43%) ** • Colonoscopy [over 50%] [53%, 65% ] *Cohrane review, Hewitson P, Am J Gastroenterol. 2008 ** Wendy Atkins 2010

  16. Colonoscopy Trials • Many cohort and case control studies on colonoscopy screening showing over 50% decrease in incidence and mortality. Incidence Mortality • Winawer et al NEJM 1993 76%, 88% and 90% • Müller AD et al Ann Int Med 1995 59% • Citarda F et al. Gut 2001 66% • Kahi CJ et alClin Gastroenterol et Hepatol 2009 67% 65% • Brenner H et al. Ann Int Med 2011 77%

  17. Two randomized controlled trials • The Spanish trial • 55,000 individuals , 50–69 years • iFOBT or colonoscopy screening. • Started in 2008, results are expected in 2021, after 10 years of follow-up . • TheNordic–European Initiative on Colorectal Cancer (NordICC) • multicentre, multinational randomised trial • 66,000 individuals • colonoscopy or no screening. • started screening in 2009. A 15-year follow-up period after screening is planned,with an interimanalysis after 10 years,due about year 2022 • Landspitalinn has been in the NordICC group from the beginning and there has been an interest to contribute to the trial. • Due to opportunistic screening in Reykjavik we are probably not able to take part.

  18. Opportunistic screening • Increasing ! • In 10 years ?? • Are we going to wait for 10 years ? • What if there is no difference ? • Is it ethical to fight pollution in the control groups ? • The control groups are going to be polluted whatever we do.

  19. What can we do in Iceland ? • Registry for colonoscopies and polyps (histology) • Improve the quality of the colonoscopies: • Training programmes. • Quality control (Gastronet). • Start screening. • Preferably with colonoscopy. • Within the NordICC study.

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