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HARVARD MEDICAL SCHOOL

Optimizing Triage to Preoperative Chemoradiation in T2 Rectal Cancer Based on Mesorectal Lymph Node Size: A Decision Analysis Informed by Patient Outcomes. Chang, Connie Y., M.D., Pandharipande, Pari, M.D., M.P.H., Harisinghani, Mukesh, M.D., Gazelle, G. Scott, M.D., M.P.H., Ph.D. HARVARD

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HARVARD MEDICAL SCHOOL

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  1. Optimizing Triage to Preoperative Chemoradiation in T2 Rectal Cancer Based on Mesorectal Lymph Node Size: A Decision Analysis Informed by Patient Outcomes Chang, Connie Y., M.D., Pandharipande, Pari, M.D., M.P.H., Harisinghani, Mukesh, M.D., Gazelle, G. Scott, M.D., M.P.H., Ph.D. HARVARD MEDICAL SCHOOL

  2. Background: Rectal Cancer • MRI has had increasing role in preoperative planning for rectal cancer (T-stage) • Large degree of overlap of size of normal/reactive and cancer-containing peri-rectal lymph nodes.

  3. Lymph Node Staging in Rectal Cancer Stage T2 rectal cancer Perirectal lymph nodes

  4. Purpose • To optimize key patient outcomes in T2 rectal cancer by identifying mesorectal lymph node size criteria for triage to preoperative chemoradiation.

  5. Methods • Decision-Analytic Model • Model inputs derived from literature • T2 rectal cancer

  6. Methods Treat All Patients with Pre-operative Chemoradiation Treat If any Mesorectal Lymph Nodes are > 3 mm Stage T2 Rectal Cancer Treat If any Mesorectal Lymph Nodes are > 5 mm Treat If any Mesorectal Lymph Nodes are > 7 mm No Preoperative Chemoradiation for Any Patients

  7. Methods: Four Disease Scenarios

  8. Methods: Four Disease Scenarios

  9. Methods: Four Disease Scenarios

  10. Methods: Four Disease Scenarios TP FP FN TN

  11. Methods: Four Disease Scenarios TP FP FN TN

  12. Methods: Four Disease Scenarios TP FP FN TN

  13. Base Case Analysis * From Kim, et al (2004)

  14. Base Case Analysis * Sauer, et al (2004)

  15. Secondary Analysis • Individual node radiology-pathology correlation • Schnall et al (1994), Brown et al (2003) • Expanded data (318 nodes from 78 patients) • Subject to “clustering bias” • USPIO lymph node contrast agent • Lahaye et al (2008)

  16. Sensitivity Analysis • Performed to assess the impact of uncertainty in key model parameter estimates upon clinical outcomes • Calculated 95% confidence intervals for sensitivity and specificity of each strategy • Repeated analysis with upper and lower limits of the confidence intervals.

  17. Results – Base Case Analysis

  18. Results – Base Case Analysis ● Lowest Value ● ●

  19. Results – Base Case Analysis ● Lowest Value * * ● * * * * *

  20. Results – Base Case Analysis ● Lowest Value ●

  21. Results –Secondary and Sensitivity Analysis • Individual node analysis – similar pattern of results to base case analysis • Upper limits of all confidence intervals – differed for long-term chemoradiation toxicity • Minimized if treat no patients preoperatively • Lower limits of all confidence intervals – differed only for acute chemoradiation toxicity • Minimized if treat patients with LNs > 7 mm

  22. Results – Sensitivity AnalysisUSPIO-Enhancement * * *

  23. Limitations • Reduction of a complex disease into a simple decision model. • Correct identification of stage T2 rectal cancer

  24. Conclusions • Lymph node size criteria used is based on outcome prioritized at the individual patient level • Acute toxicity – treat no patients • Long-term toxicity – treat > 7 mm • Local recurrence – treat all patients • A higher threshold may better balance all three outcomes.

  25. Conclusions • USPIO-positivity should be better than all size criteria for triaging patients to pre-operative chemoradiation.

  26. Thank you!

  27. References • Brown G, Richards, CJ, Bourne, MW, et al. Morphologic predictors of lymph node status in rectal cancer with use of high-spatial-resolution MR imaging with histopathologic comparison. Radiology 2003; 227:371-377. • Kim JH, Beets GL, Kim, MJ, et al. High resolution MR imaging for nodal staging in rectal cancer: are there any criteria in addition to the size? EJR 2004; 52:78-83.

  28. References • Lahaye MJ, Engelen SME, Kessels AGH, et al. USPIO-enhanced MR Imaging for Nodal Staging in Patients with Primary Rectal Cancer: Predictive Criteria. Radiology 2008; 246(3), 804-811. • Schnall MD, Furth EE, Rosato EF, Kressel HY. Rectal tumor stage: Correlation of endorectal MR imaging and pathologic findings. Radiology 1994; 190:709-714. • Sauer R, Becker H, Hohenberger W, et al. Preoperative versus postoperative chemoradiotherapy for rectal cancer. NEJM 2004; 351;17:1731-40.

  29. Secondary Analysis * Schnall et al (1994) and Brown et al (2003)

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