Radiation therapy target volume reduction in pediatric rhabdomyosarcoma

Implications for patterns of disease recurrence and overall survival

Authors

  • Bree R. Eaton MD,

    Corresponding author
    1. Department of Radiation Oncology, Winship Cancer Institute of Emory University, Atlanta Georgia
    • 1365 Clifton Road NE, Building A, Suite CT 104, Atlanta, GA 30322. Fax: (404) 778-3643

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  • Mark W. McDonald MD,

    1. Department of Radiation Oncology, Winship Cancer Institute of Emory University, Atlanta Georgia
    Current affiliation:
    1. Mark McDonald's current affiliation: Indiana University Health Proton Therapy Center, Bloomington, Indiana
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  • Sungjin Kim MS,

    1. Department of Biostatistics and Bioinformatics, Winship Cancer Institute of Emory University, Atlanta Georgia
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  • Robert B. Marcus Jr. MD,

    1. Department of Radiation Oncology, Winship Cancer Institute of Emory University, Atlanta Georgia
    Current affiliation:
    1. Robert Marcus' current affiliation: Gulf Region Radiation Oncology, Pensacola, Florida
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  • Anna L. Sutter MS,

    1. Department of Radiation Oncology, Winship Cancer Institute of Emory University, Atlanta Georgia
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  • Zhengjia Chen PhD,

    1. Department of Biostatistics and Bioinformatics, Winship Cancer Institute of Emory University, Atlanta Georgia
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  • Natia Esiashvili MD

    1. Department of Radiation Oncology, Winship Cancer Institute of Emory University, Atlanta Georgia
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Abstract

BACKGROUND:

The use of radiation therapy (RT) “cone-down” boost to reduce high-dose treatment volumes according to tumor response to induction chemotherapy in patients with pediatric rhabdomyosarcoma (RMS) may reduce treatment morbidity, yet the impact on tumor control is unknown.

METHODS:

Fifty-five children, including 18 (33%) with parameningeal (PM) RMS and 37 (67%) with non-PM RMS, who received definitive treatment with chemotherapy and RT from April 2000 through January 2010 were retrospectively reviewed.

RESULTS:

In total, 28 patients (51%) received a cone-down boost. The high-dose boost volume was reduced by a median of 56% of the initial target volume (range, 5%-91%). The median time to initiating RT was 3 weeks for patients with PM RMS and 16 weeks for patients with non-PM RMS (P < .001). After a median follow-up of 41 months, local failure occurred in 5 patients (9%), including 2 patients who received a cone-down boost, and there were no marginal failures. Twelve patients (67%) with PM RMS had intracranial tumor extension. In this subgroup, 4 patients (30%) who received a cone-down boost and had ≥ 3 weeks between chemotherapy and RT initiation experienced leptomeningeal failure as their first site of disease progression, and a delayed time to RT initiation was associated with decreased survival (P = .055)

CONCLUSIONS:

A cone-down boost allowed for significant reductions in high-dose RT treatment volume while maintaining excellent tumor control in most patients. However, in the subset of patients with PM RMS and intracranial tumor extension, early RT initiation and wider margin RT to cover adjacent areas at high risk for meningeal extension may be more important for adequate disease control. Cancer 2013. © 2012 American Cancer Society.

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