Protons Offer Reduced Normal-Tissue Exposure for Patients Receiving Postoperative Radiotherapy for Resected Pancreatic Head Cancer

Journal Article · Tue May 01 04:00:00 EDT 2012 · International Journal of Radiation Oncology, Biology and Physics

DOI:https://doi.org/10.1016/J.IJROBP.2011.05.045· OSTI ID:22056320

Huh, Soon N ^[1]; Prado, Karl L; Yi, Byong Y; Sharma, Navesh K ^[2]; Ho, Meng W; Hoppe, Bradford S; Mendenhall, Nancy P; Li, Zuofeng ^[1]; Regine, William F ^[2]

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1. University of Florida Proton Therapy Institute, Jacksonsville, FL (United States)
2. Department of Radiation Oncology, University of Maryland, Baltimore, MD (United States)

Purpose: To determine the potential role for adjuvant proton-based radiotherapy (PT) for resected pancreatic head cancer. Methods and Materials: Between June 2008 and November 2008, 8 consecutive patients with resected pancreatic head cancers underwent optimized intensity-modulated radiotherapy (IMRT) treatment planning. IMRT plans used between 10 and 18 fields and delivered 45 Gy to the initial planning target volume (PTV) and a 5.4 Gy boost to a reduced PTV. PTVs were defined according to the Radiation Therapy Oncology Group 9704 radiotherapy guidelines. Ninety-five percent of PTVs received 100% of the target dose and 100% of the PTVs received 95% of the target dose. Normal tissue constraints were as follows: right kidney V18 Gy to <70%; left kidney V18 Gy to <30%; small bowel/stomach V20 Gy to <50%, V45 Gy to <15%, V50 Gy to <10%, and V54 Gy to <5%; liver V30 Gy to <60%; and spinal cord maximum to 46 Gy. Optimized two- to three-field three-dimensional conformal proton plans were retrospectively generated on the same patients. The team generating the proton plans was blinded to the dose distributions achieved by the IMRT plans. The IMRT and proton plans were then compared. A Wilcoxon paired t-test was performed to compare various dosimetric points between the two plans for each patient. Results: All proton plans met all normal tissue constraints and were isoeffective with the corresponding IMRT plans in terms of PTV coverage. The proton plans offered significantly reduced normal-tissue exposure over the IMRT plans with respect to the following: median small bowel V20 Gy, 15.4% with protons versus 47.0% with IMRT (p = 0.0156); median gastric V20 Gy, 2.3% with protons versus 20.0% with IMRT (p = 0.0313); and median right kidney V18 Gy, 27.3% with protons versus 50.5% with IMRT (p = 0.0156). Conclusions: By reducing small bowel and stomach exposure, protons have the potential to reduce the acute and late toxicities of postoperative chemoradiation in this setting.

• OSTI ID: 22056320
• Journal Information: International Journal of Radiation Oncology, Biology and Physics, Journal Name: International Journal of Radiation Oncology, Biology and Physics Journal Issue: 1 Vol. 83; ISSN IOBPD3; ISSN 0360-3016
• Country of Publication: United States
• Language: English

Related Subjects

62 RADIOLOGY AND NUCLEAR MEDICINE
DOSIMETRY
HEAD
KIDNEYS
LIVER
NEOPLASMS
PANCREAS
PATIENTS
PLANNING
PROTONS
RADIATION DOSE DISTRIBUTIONS
RADIATION DOSES
RADIOTHERAPY
RECOMMENDATIONS
SPINAL CORD
STOMACH
TOXICITY