Dose escalation with proton or photon radiation treatment for pancreatic cancer.
OBJECTIVE
The purpose was to determine the optimal radiation therapy modality (three-dimensional conformal photon-radiation therapy [3DCRT], intensity-modulated photon-radiation therapy [IMRT], or passive-scattering proton therapy [PT]) for safe dose escalation (72Gy) in pancreatic tumors in different positions relative to organs at risk (OAR) anatomy.


METHODS
A 3-cm pancreatic tumor was virtually translated every 5mm over 5cm laterally. We generated two plans for each of the three techniques (3DCRT, IMRT, and PT), one that adhered to target coverage objectives and another to meet OAR sparing constraints with best coverage. We evaluated distances between gross tumor volumes and isodoses and compared dose-volume histograms.


RESULTS
IMRT was more conformal in higher gradient dose regions circumferentially, but tumor positions with anteriorly located small bowel benefited more from PT. 3DCRT plans resulted in inadequate target coverage. The V(15Gy) (mean+/-SD) were as follows for the IMRT and PT plans, respectively: stomach, 48%+/-4% vs 5%+/-3% (p<0.0001); and small bowel, 61%+/-8% vs 9%+/-4% (p<0.0001).


CONCLUSIONS
Our study showed that the optimal radiation therapy modality for safe dose escalation depends on pancreatic tumor position in relation to OAR anatomy.
Bouchard
Myriam
M
Department of Radiation Physics, The University of Texas M.D. Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, TX 77030, USA.
Amos
Richard A
RA
Briere
Tina M
TM
Beddar
Sam
S
Crane
Christopher H
CH
D006801:Humans; D010190:Pancreatic Neoplasms / Q000532:radiotherapy*; D017785:Photons / Q000627:therapeutic use*; D061766:Proton Therapy; D011879:Radiotherapy Dosage; D020266:Radiotherapy, Conformal / Q000379:methods*; D011522:Protons
D011522:Protons