Esophageal cancer dose escalation using a simultaneous integrated boost technique.
OBJECTIVE
We previously showed that 75% of radiation therapy (RT) failures in patients with unresectable esophageal cancer are in the gross tumor volume (GTV). We performed a planning study to evaluate if a simultaneous integrated boost (SIB) technique could selectively deliver a boost dose of radiation to the GTV in patients with esophageal cancer.


METHODS
Treatment plans were generated using four different approaches (two-dimensional conformal radiotherapy [2D-CRT] to 50.4 Gy, 2D-CRT to 64.8 Gy, intensity-modulated RT [IMRT] to 50.4 Gy, and SIB-IMRT to 64.8 Gy) and optimized for 10 patients with distal esophageal cancer. All plans were constructed to deliver the target dose in 28 fractions using heterogeneity corrections. Isodose distributions were evaluated for target coverage and normal tissue exposure.


RESULTS
The 50.4 Gy IMRT plan was associated with significant reductions in mean cardiac, pulmonary, and hepatic doses relative to the 50.4 Gy 2D-CRT plan. The 64.8 Gy SIB-IMRT plan produced a 28% increase in GTV dose and comparable normal tissue doses as the 50.4 Gy IMRT plan; compared with the 50.4 Gy 2D-CRT plan, the 64.8 Gy SIB-IMRT produced significant dose reductions to all critical structures (heart, lung, liver, and spinal cord).


CONCLUSIONS
The use of SIB-IMRT allowed us to selectively increase the dose to the GTV, the area at highest risk of failure, while simultaneously reducing the dose to the normal heart, lung, and liver. Clinical implications warrant systematic evaluation.
Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA. jwelsh@mdanderson.org
James
J
Welsh
Matthew B
MB
Palmer
Jaffer A
JA
Ajani
Zhongxing
Z
Liao
Steven G
SG
Swisher
Wayne L
WL
Hofstetter
Pamela K
PK
Allen
Steven H
SH
Settle
Daniel
D
Gomez
Anna
A
Likhacheva
James D
JD
Cox
Ritsuko
R
Komaki
D000230:Adenocarcinoma / Q000000981:diagnostic imaging / Q000473:pathology / Q000532:radiotherapy*; D019583:Dose Fractionation, Radiation; D004938:Esophageal Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology / Q000532:radiotherapy*; D006321:Heart / Q000000981:diagnostic imaging / Q000528:radiation effects; D006801:Humans; D008099:Liver / Q000000981:diagnostic imaging / Q000528:radiation effects; D008168:Lung / Q000000981:diagnostic imaging / Q000528:radiation effects; D058958:Organs at Risk / Q000000981:diagnostic imaging / Q000528:radiation effects*; D011832:Radiation Injuries / Q000517:prevention & control; D011859:Radiography; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D020266:Radiotherapy, Conformal / Q000379:methods; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods*; D012189:Retrospective Studies; D013116:Spinal Cord / Q000000981:diagnostic imaging / Q000528:radiation effects; D047368:Tumor Burden / Q000528:radiation effects*