Feasibility of using intensity-modulated radiotherapy to improve lung sparing in treatment planning for distal esophageal cancer.
OBJECTIVE
To evaluate the feasibility whether intensity-modulated radiotherapy (IMRT) can be used to reduce doses to normal lung than three-dimensional conformal radiotherapy (3 DCRT) in treating distal esophageal malignancies.


METHODS
Ten patient cases with cancer of the distal esophagus were selected for a retrospective treatment-planning study. IMRT plans using four, seven, and nine beams (4B, 7B, and 9B) were developed for each patient and compared with the 3 DCRT plan used clinically. IMRT and 3 DCRT plans were evaluated with respect to PTV coverage and dose-volumes to irradiated normal structures, with statistical comparison made between the two types of plans using the Wilcoxon matched-pair signed-rank test.


RESULTS
IMRT plans (4B, 7B, 9B) reduced total lung volume treated above 10 Gy (V(10)), 20 Gy (V(20)), mean lung dose (MLD), biological effective volume (V(eff)), and lung integral dose (P<0.05). The median absolute improvement with IMRT over 3DCRT was approximately 10% for V(10), 5% for V(20), and 2.5 Gy for MLD. IMRT improved the PTV heterogeneity (P<0.05), yet conformity was better with 7B-9B IMRT plans. No clinically meaningful differences were observed with respect to the irradiated volumes of spinal cord, heart, liver, or total body integral doses.


CONCLUSIONS
Dose-volume of exposed normal lung can be reduced with IMRT, though clinical investigations are warranted to assess IMRT treatment outcome of esophagus cancers.
Chandra
Anurag
A
Department of Radiation Oncology, University of Texas, M.D. Anderson Cancer Center, Houston, USA.
Guerrero
Thomas M
TM
Liu
H Helen
HH
Tucker
Susan L
SL
Liao
Zhongxing
Z
Wang
Xiaochun
X
Murshed
Hasan
H
Bonnen
Mark D
MD
Garg
Amit K
AK
Stevens
Craig W
CW
Chang
Joe Y
JY
Jeter
Melinda D
MD
Mohan
Radhe
R
Cox
James D
JD
Komaki
Ritsuko
R
D004307:Dose-Response Relationship, Radiation; D004938:Esophageal Neoplasms / Q000532:radiotherapy*; D006801:Humans; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods*; D016896:Treatment Outcome