Debate: General surveillance/screening for colon cancer in a resource constrained environment is imperative

Transcription

1 Debate: General surveillance/screening for colon cancer in a resource constrained environment is imperative Dr. Meryl Oyomno Department of surgery, University of Pretoria

2 INTRODUCTION Screening is the systematic application of a test to identify individuals at sufficient risk of a specific disorder (e.g. colorectal cancer CRC) to warrant further investigation or direct preventive action, amongst asymptomatic persons associated with cure and improved survival

3 CRC screening tests Average risk individual Fecal occult blood test FOBT (1yr) Fecal immunochemical test FIT (1yr) Multi-targeted stool DNA test (MT-sDNA) (3yr) Flexible sigmoidoscopy FS (5yr) Colonoscopy (10yr) CT colonography (5yr) Capsule colonoscopy Septin 9 assay.

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5 CRC Surveillance

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7 Debate: General surveillance/screening for colon cancer in a resource constrained environment is imperative

8 Arguments against CRC screening 1. CRC incidence 2. Need for basic health care rather than preventative measures 3. Evidence for screening, how good is it? 4. False positives and negatives 5. Complications 6. Overall mortality 7. Means and resources 8. Poor attendance/ non-compliance 9. Personal responsibility 10. Socio-economic status SES 11. Culture

9 1. CRC Incidence Worldwide: 3 rd most commonly diagnosed cancer. UK: lung 2 nd most common cancer after breast Ca. 3 rd most common cancer after prostate and >36,000 new cases diagnosed each year South Africa:

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13 2. Need for basic health care rather than preventative measures Developed countries have already secured certain standards of healthcare for the sick e.g. childhood vaccination, maternal health etc. and therefore screening can be next on the agenda Developing countries this isn t the case. There is a need to ensure equitable distribution of the little available resources. Focus on the basics with the little resources available e.g. childhood vaccination, decreasing maternal obstetric and neonatal mortality, so as to achieve maximal impact and good for the larger population.

14 3. Evidence for screening, how good is it? Fecal occult blood test FOBT: RCT showed a 15-33% decrease in mortality from CRC after 8-13 yr. follow-up period With 5% lifetime risk of CRC and 50% mortality from the disease, the risk of dying from CRC is 2.5% without FOBT.. About 98% of us will die from something else. How do you sell these figures to doctors and the public? Flexible sigmoidoscopy FS: A single FS screening between ages 55 and 64 years was associated with a substantial reduction of CRC incidence and mortality. CRC incidence was reduced by 31% (RR = 0.69; 95% CI = 0.56 to 0.86) and mortality was reduced by 38% (RR = 0.62; 95% CI = 0.40 to 0.96) compared with the control group. Norwegian Colorectal Cancer Prevention (NORCCAP) screening study: no difference in diagnostic yield between the FS group and the FS plus FOBT group screening with regards to detection of CRC or high-risk adenomas

15 Norwegian RCT ( & 15yrs follow-up) Adults 54-64yrs at base line Screening FS vs. FS+FOBT Norwegian Colorectal Cancer Prevention (NORCCAP) Trial Measurements: Age-adjusted CRC incidence and mortality stratified by sex RESULTS: 98,678 persons (20,552 screened, 78,126 no screening) Adherence: women 64.7%, men 61.4% Absolute risks for death from CRC in women: 0.60% in the screening group and 0.59% in the control group (risk difference, 0.01 percentage point [CI, 0.16 to 0.18 percentage point]; HR, 1.01 [CI, 0.77 to 1.33]), in men were 0.49% and 0.81%, respectively (risk difference, 0.33 percentage point [CI, 0.49 to 0.16 percentage point]; HR, 0.63 [CI, 0.47 to 0.83]) (P for heterogeneity = 0.014). CONCLUSION: Offering sigmoidoscopy screening in Norway reduced CRC incidence and mortality in men but had little or no effect in women.

16 4. False positives and negatives FOBT (Haemoccult II) uses guaiac, a resin that oxidizes and changes color in the presence of hemoglobin. A poor test (30% specificity, 98% sensitivity) 2 17% positive predictive value ( 98% of patients with a positive FOBT, have a normal colonoscopy) Anxiety and psychological harm Wasted resources False sense of security Late diagnosis with poor outcome

17 5. Complications Screening: healthy, asymptomatic individuals NORCCAP Trial: 6 perforations (1:336) Rectal bleeding requiring admission Perforation rate of 1:769 Infection secondary to contaminated scopes Cardiovascular complications of mechanical bowel preparation and sedation Mortality rate: 1 in 16,745

18 6. Overall mortality While screening decreases CRC inherent mortality, it does not decrease overall mortality.

19 7. Means and resources Do we have enough trained endoscopists? UK Only 17.0% of colonoscopists have received supervised training for their first 100 colonoscopies and only 39.3% have attended a training course (Bowles et al. 2004) 2013: 1,289 trained medical gastroenterologists (Romaya C & Lockett M. 2013, GASTROENTEROLOGY WORKFORCE REPORT) SA population of 57.7million 3.2 million persons over 64 years 36.9 million between 15 and 64 years old. < 500 trained colonoscopists Currently, we simply do not have enough trained endoscopists.

20 8. Poor attendance Danish RCT: FOBT biennial screening The more screening rounds individuals are enrolled into, the poorer the attendance. lesser reduction in mortality from CRC. Dropped from 18% to 11% after 5 screening rounds

21 9. Personal responsibility Some may abandon healthy lifestyles if they believe that screening will pick up cancers at an early stage when it is more likely to be curable.

22 10. Socio-economic status Gap between the rich and poor Canada ( ) people, 21.2% received a colorectal investigation Multivariate analysis: significant association between receipt of any colorectal investigation and income (p < 0.001); People in the highest-income quintile had higher odds of receiving any colorectal investigation (adjusted odds ratio [OR] 1.38; 95% confidence interval [CI] ) and of receiving colonoscopy (adjusted OR 1.50; 95% CI ). These inequities persisted even after the launch of the programs to widely educate the public Ontario Canada study ( ) Immigrants and the poor are less likely to be screened for CRC Residents living in low-income neighborhoods were consistently and significantly less likely to have a FOBT and be 'up-to-date' with CRC screening than long-term residents living in high-income neighborhoods ( %; % respectively).

23 11. Culture Screening modalities should be culturally appropriate to the target population. Public education

24 Summary The ideal screening method Money wasted on colonoscopy and consultation fees following false positive screening tests. A resource-constrained environment, Equitable distribution resources Wiser to spend this money on treating actual patients with CRC rather than healthy members of the public. First determine local data (incident rates, age etc.) CRC data base (screening, stage, surveillance) Finnish model

25 Ensure that there will be adequate numbers of trained endoscopists to carry out safe screening colonoscopy for those that will have positive screening tests Screening should only be done if it is done in an organized fashion and linked to quality assurance programmes.

26 References 1. Bernie, T., et al. (1998). "A systematic review of the effects of screening for colorectal cancer using the faecal occult blood test, hemoccult." BMJ 317(7158): Bowles, C., et al. (2004). "A prospective study of colonoscopy practice in the UK today: are we adequately prepared for national colorectal cancer screening tomorrow?" Gut 53(2): Force, U. P. T. (1996). Guide to clinical preventive services, Alexandria, VA: International Medical Publishing. 4. Gondal, G., et al. (2003). "The Norwegian Colorectal Cancer Prevention (NORCCAP) screening study: baseline findings and implementations for clinical work-up in age groups years." Scandinavian journal of gastroenterology 38(6): Hakama, M. (2002). "Cancer screening for medical oncologists: definitions and aims." Annals of oncology 13(suppl_4): Hardcastle, J. D., et al. (1996). "Randomised controlled trial of faecal-occult-blood screening for colorectal cancer." The Lancet 348(9040): Hoff, G. and M. Bretthauer (2006). "The science and politics of colorectal cancer screening." PLoS medicine 3(1): e Holme, Ø., et al. (2018). "Long-Term Effectiveness of Sigmoidoscopy Screening on Colorectal Cancer Incidence and Mortality in Women and Men: A Randomized Trial." Annals of internal medicine 168: Honein-AbouHaidar, G. N., et al. (2013). "Trends and inequities in colorectal cancer screening participation in Ontario, Canada, " Cancer Epidemiol 37(6): Kronborg, O., et al. (2004). "Randomized study of biennial screening with a faecal occult blood test: results after nine screening rounds." Scandinavian journal of gastroenterology 39(9): Ladouceur, R. and F. CCMF (2003). "Colon Cancer Screening." Presented at Débat: Contre Le Dépistage du Cancer du Colon. 12. Malila, N., et al. (2005). "Colorectal cancer screening in Finland: details of the national screening programme implemented in Autumn 2004." Journal of medical Screening 12(1):

27 13. Mandel, J. S., et al. (1993). "Reducing mortality from colorectal cancer by screening for fecal occult blood." New England Journal of Medicine 328(19): Organization, W. H. (2002). National cancer control programmes: policies and managerial guidelines, World Health Organization. 15. Rex, D. K., et al. (2017). "Colorectal cancer screening: recommendations for physicians and patients from the US Multi-Society Task Force on Colorectal Cancer." The American journal of gastroenterology 112(7): Samuels, S. (2014). Alex residents kill owls because they are used for witchcraft. Online: alexnews: online media journalism. 17. Segnan, N., et al. (2011). "Once-only sigmoidoscopy in colorectal cancer screening: follow-up findings of the Italian Randomized Controlled Trial SCORE." Journal of the National Cancer Institute 103(17): Singh, S. M., et al. (2004). "Association of socioeconomic status and receipt of colorectal cancer investigations: a population-based retrospective cohort study." Canadian Medical Association Journal 171(5): Solomon, M. J. and R. S. McLeod (1994). "Periodic health examination, 1994 update: 2. Screening strategies for colorectal cancer. Canadian Task Force on the Periodic Health Examination." CMAJ: Canadian Medical Association Journal 150(12): Pillay-van Wyk, V et al, (2016). Mortality trends and differentials in South Africa from 1997 to 2012: second National Burden of Disease Study. The Lancet Global Health, 4(9): Thank you