1640 dr wong nan soon cancer screening and saving lives, healthcare costs

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1640 dr wong nan soon cancer screening and saving lives, healthcare costs

  1. 1. Cancer ScreeningSaving Lives and Healthcare Costs Dr Wong Nan Soon Consultant Medical Oncologist Oncocare Cancer Centre Mt Elizabeth Medical Centre Adjunct Associate Professor Department of Clinical Sciences Duke-NUS
  2. 2. Avoid Overzealous Screening!
  3. 3. Message• Cancer is the commonest cause of death in Singapore• Cancer incidence increases with age BUT• Effective cancer screening is available for common malignancies• Cancer awareness and compliance with screening recommendations can contribute to healthy aging workforce
  4. 4. Scope• Biology of cancer• Cancer epidemiology in Singapore• Principles behind screening• Details of screening tests available
  5. 5. What Exactly is Cancer? Hanahan and Weinberg. Cell 2011
  6. 6. Stepwise Progression of CancerDynamics of Cancer: Incidence, Inheritance, and Evolution. Frank SA.Princeton (NJ):Princeton University Press; 2007.Vogelstein et al.,New Engl J Med 1988
  7. 7. Cancer: Top Killer in Singapore Ministry of Health: Statistics
  8. 8. Cancer Burden Singapore Cancer Registry Interim Report 2005-2009
  9. 9. Common Cancers by GenderSingapore Cancer Registry Interim Report 2005-2009
  10. 10. Age Specific Cancer Incidence Singapore Cancer Registry Interim Report 2005-2009
  11. 11. What is Prevention• Primary prevention – Prevents onset of disease – Removes risk factors eg smoking cessation, avoiding HRT• Secondary – Detects disease at early asymptomatic stage – Stops disease progression – Eg screening for breast cancer, colon cancer• Tertiary – Prevents disease deterioration and complications – Eg lowering glucose in known diabetic
  12. 12. What is Screening• Detection of unrecognized risk factor or disease in well patients• Can be part of primary or secondary prevention• Involves clinical examination, blood tests, procedures such as mammography, colonoscopy
  13. 13. Should We Screen Everyone for Every Disease?• Incidence of disease• Morbidity and mortality of disease• Is primary prevention possible• Is early intervention effective/ curative• Performance of screening test – Specificity and sensitivity – Safety, side effects, acceptability – Cost
  14. 14. Evaluating Screening Test Avoiding Bias• Screen detected cancers vs symptomatic cancers – Lead time bias – Length time bias – Overdiagnosis bias – Selection bias
  15. 15. Recommended ScreeningCancer Type Average Risk High RiskBreast cancer Yes YesColorectal cancer Yes YesCervical cancer Yes YesOvarian cancer No Yes (BRCA mutation)Uterine cancer No Yes (Lynch syndrome)Lung cancer No Yes (Heavy smokers)Liver cancer No Yes (Hepatitis B carriers)Prostate cancer No Yes (Strong family history)NPC No Yes (Strong family history)
  16. 16. Mammography
  17. 17. Mammography
  18. 18. Screening MammogramStudy Protocol Frequency Population Subgroup Invited Control F/U RR (95%CI)HIP 2V MM, q12m x 4 40-64 40-49 14432 14701 18 0.77(0.53-1.11)(1963-1969) CBE 50-64 16568 16299 18 0.80(0.59-1.08)Edinburgh 1 or 2V q24m x4 45-64 45-49 11755 10641 14 0.83(0.54-1.27)(1979-1988) MM, CBE 50-64 11245 12359 10 0.85(0.62-1.15)Kopparberg 1V MM q24mx4 40-74 40-49 9650 5009 20 0.76(0.42-1.40)(1977-1985) 50-74 28939 13551 20 0.52(0.39-0.70)Ostergotland 1V MM q24mx4 40-74 40-49 10240 10411 20 1.06(0.65-1.76)(1977-1985) 50-74 28229 26830 20 0.81(0.64-1.03)Malmo 1 or 2V MM q18-24m x5 45-69 45-49 13528 12242 12.7 0.64(0.45-0.89)(1976-1990) 50-69 17134 17165 9 0.86(0.64-1.16)Stockholm 1V MM q28mx2 39-59 39-49 11724 12015 11.4 1.01(0.51-2.02)(1981-1985) 50-59 9276 14217 7 0.65(0.4-1.08)Gothenberg 2V MM q18mx5 39-59 39-49 11724 14217 12 0.56(0.32-0.98)(1982-1988) 50-59 9276 16394 13 0.91(0.61-1.36)CNBSS1 2V MM Q12m x5 40-49 40-49 25214 25216 11-16 1.07(0.75-1.52)CNBSS2 CBE 50-59 50-59 19711 19694 13 1.02(0.78-1.33)(1980-1987)UK AGE 2V MM Q12m x 7 39-41 - 53914 107007 11 0.83 (0.66-1.04)(1991-1997) year 1 then 1 V MM Smith RA, Dorsi CJ. Screening for breast cancer in : Diseases of the breast, Lippincott WW, Philadelphia USA, 2004
  19. 19. Benefits and Risks Fletcher and Elmore, New Engl J Med 2003 Warner, New Engl J Med 2011
  20. 20. Impact at Population LevelTrends in female breast cancer mortality rates by ethnicity, USA 1975-2002
  21. 21. Screening Mammography GuidelinesAgency Frequency Age 40-49 Age 50-69 Age>69US Preventive Services 2 yrs Discuss Yes YesTask Force Q2 yrsCanadian Task Force on 1-2 yrs Discuss Yes NoPreventive Health CareACS 1 yr Yes Yes YesNCI 1-2 yrs Yes Yes YesHPB Singapore/MOH 2 years Discuss Yes - Q1 year
  22. 22. Other Modalities– MRI • Prospective data in familial breast cancer1,2 • Higher sensitivity, lower specificity • Impact on mortality not determined • Higher cost– Digital mammography • Recent randomised trial showed higher accuracy in women age <503 1. Warner E et al. JAMA 292:1317, 2004 2. Kriege M et al. NEJM 351:427, 2004 3. Pisano ED et al. NEJM 353:1846, 2005
  23. 23. Colon Cancer Screening
  24. 24. What is Colorectal Cancer
  25. 25. Symptoms and Signs of Colorectal Cancer• Blood in stools• Change in stool calibre• Change in bowel habits• Sense of incomplete bowel emptying• Abdominal distention• Weight loss• Anemia
  26. 26. Why is Screening Useful?• There is a long period in the early stages where there are no symptoms.• Colorectal cancer develops from polyps or adenomas. Removing polyps prevents cancer.
  27. 27. How is Screening Performed?• Faecal Tests – Occult blood test • Guaic based • Immunohistochemical test – Stool DNA• Colonoscopy• Virtual (CT) colonoscopy• Flexible sigmoidoscopy• Double contrast barium enema
  28. 28. Faecal Occult Blood Tests• Detection of microscopic amounts of blood in the stool• Cancers may bleed an invisible amount during the early stages• Different types of test kits are available – Guaic based – Immunohistochemistry
  29. 29. Faecal Occult Blood Test
  30. 30. Faecal Occult Blood Test
  31. 31. Faecal Occult Blood Test• If positive, colonoscopy required• If negative, may be sampling error
  32. 32. Faecal Occult Blood Test• False positive – Diverticular disease – Haemorrhoids – Guaic based: red meat, raw turnips, broccoli, cauliflower, radish• False negative (guaic based tests) – Non bleeding polyp/ tumour – Medications: aspirin, NSAIDS, vitamin C >750 mg per day
  33. 33. Benefits of FOBT• Incidence of stage 4 reduced by 32-47%• Incidence of colorectal cancer reduced by 20%• Death from colorectal cancer reduced by between 15% to 30% – Absolute benefit 0.8-4.6 per 1000 patients screened – Numbers needed to screen 217-1250 Walsh et al. JAMA 2003
  34. 34. Colonoscopy• Gold standard• Enables screening and intervention• No randomized trials• Based on cohort studies – Reduces incidence of colorectal cancer by 76% – False negative rate 5- 12% – Complication rate 0.03- 0.17%
  35. 35. Who, When, How Often
  36. 36. What is Cervical Cancer
  37. 37. Symptoms and Signs of Cervical Cancer• Vaginal bleed – Intermenstrual – Postcoital• Vaginal discharge• Backpain
  38. 38. Screening for Cervical Cancer
  39. 39. Cervical Cancer• Rationale for Screening – No randomized trials – Convincing evidence from observational studies • Introduction of screening programs – Decreased incidence of cervical cancer – Decreased cervical cancer deaths – Calculations suggest 90% reduction in cervical cancer mortality
  40. 40. Cervical Cancer Primary Prevention• Bivalent• Quadrivalent• Best efficacy when given prior to HPV exposure• Does not alter need for screening
  41. 41. Ministry of Health Guidelines on Screening• Cervix – Women who have had sex before or are sexually active should go for a Pap smear once every 3 years – Start at age 25
  42. 42. Conclusion• Effective cancer screening is available for common malignancies• Cancer awareness and compliance with screening recommendations can contribute to healthy aging workforce• Seek help from a medical professional to tailor a suitable screening program• Avoid overzealous screening

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