International Journal of Particle Therapy (Aug 2020)

The Importance of Verification CT-QA Scans in Patients Treated with IMPT for Head and Neck Cancers

  • Jaden D. Evans, MD,
  • Riley H. Harper, BS,
  • Molly Petersen, MS,
  • William S. Harmsen, MS,
  • Aman Anand, PhD,
  • Ashley Hunzeker, CMD,
  • Noelle C. Deiter, RTT,
  • Heather Schultz, CMD,
  • Krishan R. Jethwa, MD,
  • Scott C. Lester, MD,
  • David M. Routman, MD,
  • Daniel J. Ma, MD,
  • Yolanda I. Garces, MD,
  • Michelle A. Neben-Wittich, MD,
  • Nadia N. Laack, MD,
  • Chris J. Beltran, PhD,
  • Samir H. Patel, MD,
  • Lisa A. McGee, MD,
  • Jean-Claude M. Rwigema, MD,
  • Daniel W. Mundy, PhD,
  • Robert L. Foote, MD

DOI
https://doi.org/10.14338/IJPT-20-00006.1
Journal volume & issue
Vol. 7, no. 1
pp. 41 – 53

Abstract

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Purpose: To understand how verification computed tomography-quality assurance (CTQA) scans influenced clinical decision-making to replan patients with head and neck cancer and identify predictors for replanning to guide intensity-modulated proton therapy (IMPT) clinical practice. Patients and Methods: We performed a quality-improvement study by prospectively collecting data on 160 consecutive patients with head and neck cancer treated using spot-scanning IMPT who underwent weekly verification CT-QA scans. Kaplan-Meier estimates were used to determine the cumulative probability of a replan by week. Predictors for replanning were determined with univariate (UVA) and multivariate (MVA) Cox model hazard ratios (HRs). Logistic regression was used to determine odds ratios (ORs). P < .05 was considered statistically significant. Results: Of the 160 patients, 79 (49.4%) had verification CT-QA scans, which prompted a replan. The cumulative probability of a replan by week 1 was 13.7% (95% confidence interval [CI], 8.82-18.9), week 2, 25.0% (95% CI, 18.0-31.4), week 3, 33.1% (95% CI, 25.4-40.0), week 4, 45.6% (95% CI, 37.3-52.8), and week 5 and 6, 49.4% (95% CI, 41.0- 56.6). Predictors for replanning were sinonasal disease site (UVA: HR, 1.82, P = .04; MVA: HR, 3.64, P = .03), advanced stage disease (UVA: HR, 4.68, P < .01; MVA: HR, 3.10, P < .05), dose . 60 Gy equivalent (GyE; relative biologic effectiveness, 1.1) (UVA: HR, 1.99, P < .01; MVA: HR, 2.20, P < .01), primary disease (UVA: HR, 2.00 versus recurrent, P = .01; MVA: HR, 2.46, P = .01), concurrent chemotherapy (UVA: HR, 2.05, P < .01; MVA: not statistically significant [NS]), definitive intent treatment (UVA: HR, 1.70 versus adjuvant, P < .02; MVA: NS), bilateral neck treatment (UVA: HR, 2.07, P = .03; MVA: NS), and greater number of beams (5 beam UVA: HR, 5.55 versus 1 or 2 beams, P < .02; MVA: NS). Maximal weight change from baseline was associated with higher odds of a replan (_3 kg: OR, 1.97, P = .04; _ 5 kg: OR, 2.13, P = .02). Conclusions: Weekly verification CT-QA scans frequently influenced clinical decisionmaking to replan. Additional studies that evaluate the practice of monitoring IMPTtreated patients with weekly CT-QA scans and whether that improves clinical outcomes are warranted.

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