Danish pediatric cancer patients treated at MD Anderson: What was the actual benefit?

Reporting Author: Abigail T. Berman, MD
OncoLink
Last Modified: June 10, 2013

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Presenting Author: P. Brodin, MD
Presenting Author Affiliation: Rigshospitalet, Radiation Medicine Research Center, Department of Radiation Oncology, Copenhagen

Background

  • Every year the Rigshospitalet Hospital in Denmark refers approximately 10 pediatric patients to receive proton therapy at MD Anderson Cancer Center.
  • While it is felt that superiority of proton beam therapy to spare organs at risk makes this decision worthwhile, it is also very expensive, costing approximately 1 million DKK (or $170,000, €130,000)
  • The purpose of this study was to estimate the clinical benefit for 15 pediatric patients referred to MD Anderson (Houston, Texas) for proton therapy (in 2010-2012), compared to the state-of-the-art photon therapy available at Rigshospitalet (Copenhagen, Denmark).
    Materials and Methods:
  • 15 consecutive children (median age 7 years) were included, 6 received craniospinal irradiation (CSI) and 9 were treated with focal proton therapy.
  • Photon plans were generated for each patient using an intensity-modulated arc technique. The calculated doses of proton therapy were received from MD Anderson. The photon plans were generated in a blinded fashion, without looking at the proton plans.
  • The risk of impaired task efficiency, blindness and hearing loss was estimated using published dose-response models for pediatric data (Brodin Acta Oncol 2011, Blomstrand Neuro Oncol 2012).
  • Dosimetric differences for the heart, lungs, hippocampi, brainstem, cochleae, eyes, temporal lobes and whole brain were compared along with the estimated risks between the proton and photon plans using a Wilcoxon signed rank test.

Results

  • For the 6 CSI patients proton therapy resulted in lower doses for all risk organs except the eyes (no difference) with significantly lower mean doses (p<0.05) for the heart, lungs and temporal lobes.
    o The median of the mean doses (range) for the heart and lungs were 0.3 Gy (0.0-1.4 Gy) vs.?19.2 Gy (13.5-21.9 Gy) and 3.4 Gy (1.8-4.1 Gy) vs. 5.1 Gy (4.1-6.5 Gy) for protons vs. photons respectively.
  • The median of mean doses to all risk organs were lower with protons for the 9 focally treated patients, statistically significant for the cochleae, temporal lobes, hippocampus, and whole brain.
  • The median brainstem D1% was higher with protons.
  • In the focal irradiation group, the median (range) estimated risks of impaired task efficiency, blindness and hearing loss were 27% (24-86%) vs. 41% (25-70%) p=0.63, 0.5% (0.5-9%) vs. 1% (0.5-5%) p=1.0 and 0.1% (0.01-6%) vs. 0.5% (0.01-5%) p=0.07 for protons vs. photons respectively.

Author's Conclusions

  • Proton therapy clearly benefitted the 6 CSI patients dosimetrically.
  • For the 9 focally treated patients protons yielded lower doses to the cochleae, hippocampae, temporal lobes and whole brain for all but one patient, for which proton therapy showed no benefit.

Clinical Implications

  • This is a well-performed dosimetric comparison study showing a benefit in proton beam therapy in both craniospinal and focal irradiation. This has been shown in prior dosimetric studies from the Massachusetts General Hospital (Tarbell IJROBP 2008). Its strengths include that both plans used the same target volumes with both plans. In addition, the planners were blinded to the proton plan when completing the intensity modulated arc plan.
  • To fully answer the authors' study question of whether it beneficial from a cost perspective to send these patients to MD Anderson versus open a proton center in Denmark, a full cost effectiveness analysis must be performed.
  • The authors found that the median brainstem D1% was higher with protons. These patients were treated with double scattering proton therapy, and due to its physical properties and the proximity of many target volumes to the brainstem, this is not a surprising finding. Likely pencil beam scanning would show a decreased brainstem D1% compared to photon therapy.


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