A Comparative Evaluation of Normal Tissue Doses for Patients Receiving Radiation Therapy for Hodgkin Lymphoma on the Childhood Cancer Survivor Study and Recent Children’s Oncology Group Trials

Publication date: Available online 4 February 2016
Source:International Journal of Radiation Oncology*Biology*Physics
Author(s): Rachel Zhou, Angela Ng, Louis S. Constine, Marilyn Stovall, Gregory T. Armstrong, Joseph P. Neglia, Debra L. Friedman, Kara Kelly, Thomas J. FitzGerald, David C. Hodgson
PurposeSurvivors of pediatric Hodgkin Lymphoma (HL) are recognized to be at increased risk for delayed adverse health outcomes related to radiation therapy (RT). However, the necessary latency required to observe these late effects means that the estimated risks apply to out-dated treatments. We sought to compare the normal tissue dose received by children treated for HL and enrolled in the Childhood Cancer Survivor Study (CCSS) (diagnosed 1970-1986) with patients treated on recent Children's Oncology Group (COG) trials (enrolled 2002-2012).MethodsRT treatment planning data were obtained for 50 HL survivors randomly sampled from the CCSS cohort and applied to CT planning datasets to reconstruct normal tissue dosimetry. For comparison, normal tissue dosimetry was obtained for all 191 patients with full CT-based volumetric RT planning on COG protocols AHOD0031 and AHOD0831.ResultsFor early stage patients, mean female breast dose in the COG patients was on average 83.5% lower than CCSS patients, with an absolute reduction of 15.5Gy; for advanced stage patients mean breast dose decreased on average by 70% (11.6Gy average absolute dose reduction). The mean heart dose decreased on average by 22.9Gy (68.6%), and 17.6Gy (56.8%) for early and advanced stage patients, respectively. All dose comparisons for breast, heart, lung, and thyroid were significantly lower for patients on COG trials than CCSS participants. Reduction in prescribed dose was a major contributor to this dose reduction.ConclusionsThese are the first data quantifying the significant reduction in normal tissue dose based on actual rather than hypothetical treatment plans for children with HL. The findings provide some useful information when counselling families regarding the risks of contemporary RT.

Teaser

The Childhood Cancer Survivors Study (CCSS) is a major source of information regarding late effects among pediatric Hodgkin lymphoma (HL) survivors. In this comparison of children with HL who received radiation therapy, patients treated from 2002-2012 on Children's Oncology Group trials had normal tissue doses typically 55%-80% lower than those registered 1970-1986 on the CCSS. This finding suggests contemporary treatment should significantly reduce RT-related late toxicity compared to treatments given to patients registered in CCSS.


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