Risk Factors for Neovascular Glaucoma After Proton Beam Therapy of Uveal Melanoma: A Detailed Analysis of Tumor and Dose–Volume Parameters

Journal Article · Tue Oct 01 04:00:00 EDT 2013 · International Journal of Radiation Oncology, Biology and Physics

DOI:https://doi.org/10.1016/J.IJROBP.2013.05.051· OSTI ID:22267889

Daftari, Inder K.; Weinberg, Vivian ^[1]; Cole, Tia ^[2]; Quivey, Jeanne M.; Castro, Joseph R.; Phillips, Theodore L. ^[1]; Char, Devron H. ^[2]

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1. Department of Radiation Oncology, University of California, San Francisco, San Francisco, California (United States)
2. The Tumori Foundation, San Francisco, California (United States)

Purpose: To determine neovascular glaucoma (NVG) incidence and identify contributing tumor and dosing factors in uveal melanoma patients treated with proton beam radiation therapy (PBRT). Methods and Materials: A total of 704 PBRT patients treated by a single surgeon (DHC) for uveal melanoma (1996-2010) were reviewed for NVG in our prospectively maintained database. All patients received 56 GyE in 4 fractions. Median follow-up was 58.3 months. Analyses included the Kaplan-Meier method to estimate NVG distributions, univariate log–rank tests, and Cox's proportional hazards multivariate analysis using likelihood ratio tests to identify independent risk factors of NVG among patient, tumor, and dose–volume histogram parameters. Results: The 5-year PBRT NVG rate was 12.7% (95% confidence interval [CI] 10.2%-15.9%). The 5-year rate of enucleation due to NVG was 4.9% (95% CI 3.4%-7.2%). Univariately, the NVG rate increased significantly with larger tumor diameter (P<.0001), greater height (P<.0001), higher T stage (P<.0001), and closer proximity to the disc (P=.002). Dose–volume histogram analysis revealed that if >30% of the lens or ciliary body received ≥50% dose (≥28 GyE), there was a higher probability of NVG (P<.0001 for both). Furthermore, if 100% of the disc or macula received ≥28 GyE, the NVG rate was higher (P<.0001 and P=.03, respectively). If both anterior and posterior doses were above specified cut points, NVG risk was highest (P<.0001). Multivariate analysis confirmed significant independent risk factors to include tumor height (P<.0001), age (P<.0001), %disc treated to ≥50% Dose (<100% vs 100%) (P=.0007), larger tumor diameter (P=.01), %lens treated to ≥90% Dose (0 vs >0%-30% vs >30%) (P=.01), and optic nerve length treated to ≥90% Dose (≤1 mm vs >1 mm) (P=.02). Conclusions: Our current PBRT patients experience a low rate of NVG and resultant enucleation compared with historical data. The present analysis shows that tumor height, diameter, and anterior as well as posterior critical structure dose–volume parameters may be used to predict NVG risk.

• OSTI ID: 22267889
• Journal Information: International Journal of Radiation Oncology, Biology and Physics, Journal Name: International Journal of Radiation Oncology, Biology and Physics Journal Issue: 2 Vol. 87; ISSN IOBPD3; ISSN 0360-3016
• Country of Publication: United States
• Language: English

Related Subjects

62 RADIOLOGY AND NUCLEAR MEDICINE
EYES
MELANOMAS
MULTIVARIATE ANALYSIS
PATIENTS
PROTON BEAMS
RADIATION DOSES
RADIOTHERAPY