CT scan in Early Ling Cancer Detection

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CT scan in Early Ling Cancer Detection

  1. 1. CT scan in Early Lung Cancer Detection: Utility and Pitfalls Annette McWilliams 30 March 2007
  2. 2. Male Cancer Mortality in Canada
  3. 3. Female Cancer Mortality in Canada
  4. 4. Port, J. L. et al. Chest 2003;124:1828-1833 Disease-specific survival of patients with Stage IA tumours ≤ 2 cm or > 2 cm
  5. 5. Lee P, General Thoracic Surgery Dec 2006;132:1382-1389
  6. 6. Screening with CT • Large burden of disease  • Feasible  • Detects cancer at early stage  • Early effective treatment possible  • Low risks ? • Reduces deaths from the disease ? • Cost effective ?
  7. 7. Ongoing Issues • Utility - Mortality outcomes - Much discussion re overdiagnosis/other biases • Pitfalls - Risks - Best management of “false positive ” nodules
  8. 8. Overdiagnosis • CT pictures of HB 2 years observation
  9. 9. Overdiagnosis 5 months observation
  10. 10. Overdiagnosis • ↑ BAC vs invasive adenoCA in never cf ever smokers in Japanese data • Excellent longterm outcomes in pure BAC < 2cm • Only 1/39 cancers (2.6%) in LHS was non- invasive pure BAC & 7% in I-ELCAP • All untreated Stage 1 cancers in I-ELCAP died within FU period Sone 2003 Asamura 2003, Nakamura 2004
  11. 11. Biologically aggressive NSCLC 8mm adenocarcinoma Early 2002 N3 disease ~ 3 years later
  12. 12. Biologically aggressive NSCLC
  13. 13. Central Lung Cancers 25% cancers in LHS-all CT occult 20-75% persistence/progression on short-medium followup
  14. 14. Second Lung Cancers 2002 2005
  15. 15. Limitation of Risks Procedures/surgery for benign disease • Only 19% of suspicious lesions had diagnosis before intervention/treatment • 18-27% surgeries for benign lesions • 3% of all participants had a TTNA/med/surgery • 0.9% of all participants had unnecessary procedures (TTNA or surgery)
  16. 16. Radiation Risk • >80% of lifetime exposure is from background radiation • Data extrapolated from atomic bomb data and nuclear workers- usually one single exposure • Difficult to be accurate for exposures <100 mSv • Linear exposure model used for lower doses • Pronounced age effect • Differing organ radiation sensitivity
  17. 17. Copyright ©Radiological Society of North America, 2003 Mayo, J. R. et al. Radiology 2003;228:15-21 Figure 2. Graph compares lifetime mortality risk from cancer per sievert to age at the time of exposure
  18. 18. Brenner Radiology 2006. Relative risks in atomic bomb survivors
  19. 19. Brenner Radiology 2006. Excess cancer mortality in atomic bomb survivors
  20. 20. Radiation Risks Dose Low dose thoracic CT 1.2 mSv Standard VGH thoracic CT 2.4 mSv Mammogram 1.5 mSv to breasts Chest X-ray 0.15 mSv Background Radiation 3 mSv/year 85% screened subjects will need CT surveillance for 2 years
  21. 21. Radiation Risk Dose Low dose thoracic CT 1.2 mSv 3-5 FU thoracic CT over 2 yrs 3.6 – 6 mSv Annual surveillance 25 years 30 mSv
  22. 22. Radiation Risk Individual CT dose of 5.2 mSv Brenner 2004
  23. 23. Pulmonary Nodules • 85 % screened subjects will have abnormalities requiring surveillance for 2 years • Majority of nodules are < 5mm • How do we manage these lesions clinically?
  24. 24. Pulmonary Nodules Features that influence clinical management: 1. Size 2. Appearance 3. Longitudinal behaviour
  25. 25. Solid (90%) GGO (6%) SSN (1%) PFO (3%)
  26. 26. High Risk Population 50-74 yo ≥ 30 pack/years No prior lung cancer N= 1357 Probability of cancer = 2.6% Positive CT scan 3.1% Negative CT scan 0.7%
  27. 27. Pulmonary Nodule Probability of cancer = 0.6% Nodule < 10mmNodule < 10mm Probability of cancer = 0.2% Nodule ≥ 10mm Probability of cancer = 11.4%
  28. 28. Nodule ≥ 10mm Probability of cancer = 11.4% Solid 13.4% Semisolid 40% Nonsolid 4.9% PFO 0%
  29. 29. Nodule < 10mm Probability of cancer = 0.2% Solid 0.2% Semisolid 0% Nonsolid 0.5% PFO 0%
  30. 30. Nodule < 10mm Probability of cancer = 0.2% Solid 0.2% → 3.9% Nonsolid 0.5% → 13.6% Growth on 1 Followup CT scan
  31. 31. Nodule < 10mm Probability of cancer = 0.2% Solid 0.2% → 3.9% → 50% Nonsolid 0.5% → 13.6% → 50% Growth on 2 Followup CT scans
  32. 32. PET Imaging for Screening Detected Suspicious lesions No. Mean diameter PET positive Malignant lesions 18 15mm 39% Benign Lesions 7 13mm 43% Sensitivity = 39% Specificity = 57% PPV = 70% NPV = 27%
  33. 33. British Columbia Cancer Agency Stephen Lam Calum MacAulay Sukhinder Khattra Don Wilson Support NCIC, NIH (USA), BC Lung Association Vancouver General Hospital John Mayo Richard Finley Ayman Al-Sulaimani Ken Evans John Yee John English Julia Flint

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