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  O14 - Radiotherapy - Toxicity and Clinical Trials (ID 105)

  • Event: WCLC 2013
  • Type: Oral Abstract Session
  • Track: Radiation Oncology + Radiotherapy
  • Presentations: 1
  • Moderators:G. Pratt, S.K. Vinod
  • Coordinates: 10/29/2013, 10:30 - 12:00, Parkside Ballroom A, Level 1

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    O14.01 - Memory preservation with conformal avoidance of the hippocampus during whole-brain radiotherapy for patients with brain metastases: Preliminary results of RTOG 0933 (ID 2262)

    10:30 - 10:40  |  Author(s): W.A. Tome
    • Abstract
    • Presentation
    • Slides

    Background
    Preclinical and clinical evidence suggests that hippocampal dose during whole-brain radiotherapy (WBRT) plays a role in cognitive decline. This may be preventable by conformally avoiding the hippocampus during WBRT (HA-WBRT). RTOG 0933 was a single-arm phase II study of HA-WBRT for brain metastases with cognitive function assessments and pre-specified comparison to a historical control of WBRT without hippocampal avoidance.

    Methods
    Eligible adult patients with brain metastases received HA-WBRT to 30 Gy in 10 fractions. Standardized cognitive function assessments were performed at baseline, 2, 4, and 6 months. The primary endpoint was change in the Hopkins Verbal Learning Test-Revised Delayed Recall (HVLT-DR) at 4 months. The historical control consisted of brain metastases patients treated with WBRT on the PCI-P-120-9801 phase III trial, which demonstrated a 30% mean relative loss in HVLT-DR from baseline to 4 months. To detect a minimum relative 50% improvement in this end-point, leading to an absolute 15% or less mean relative loss in HVLT-DR following HA-WBRT, 51 analyzable patients were required to ensure 80% statistical power with a one-sided alpha=0.05.

    Results
    113 patients were accrued from April 2011-November 2012; 56 out of 100 eligible patients had non-small cell lung cancer (NSCLC). One grade 3 toxicity of cerebral edema and no grade 4 or higher toxicities were reported. Median survival was 6.9 months (95% confidence interval (95% CI) 4.8-15.2 months). 41 patients were analyzable at 4 months. Mean relative change in HVLT-DR from baseline to 4 months was +3.3% (95%CI: -8.0% to +14.6%), which was significant in comparison to the historical control (p<0.0001) and substantially exceeded the hypothesized -15% value. 28 patients were analyzable at 6 months with a mean relative change in HVLT-DR from baseline to 6 months of +4.6% (95%CI: -8.6% to +17.8%), a finding in dramatic contrast to expected continued deterioration in HVLT-DR scores from other WBRT trials. In terms of patients with NSCLC, 21 patients were analyzable at 4 months, with a mean relative change in HVLT-DR from baseline to 4 months of +10.0% (95%CI: -9.5% to +27.1%). At 6 months, 14 patients with NSCLC were analyzable, with a mean relative change in HVLT-DR from baseline to 6 months of 0.0% (95%CI: -18.5% to +18.5%).

    Conclusion
    Conformal avoidance of the hippocampus during WBRT is associated with memory preservation at 4 and 6 months follow-up in NSCLC patients, who comprised the majority of accrued and analyzable patients on this trial. These promising phase II results warrant further validation in a phase III trial, currently under development in the RTOG.

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