The accuracy of target delineation in laryngeal and hypopharyngeal cancer.
OBJECTIVE
To determine the spatial correspondence between the gross tumor volume (GTV) delineated on computer tomography (CT) and the actual tumor on histopathology.


METHODS
Sixteen patients with T3 or T4 laryngeal or hypopharyngeal cancer underwent a CT scan before total laryngectomy. The GTV was delineated on CT by three independent observers and by consensus between the three observers. After surgery, whole-mount hematoxylin-eosin stained (H&E) sections were obtained. One pathologist delineated the tumor in the H&E sections (tumorH&E). The reconstructed specimen was registered to the CT scan in order to compare the GTV to the tumorH&E in three dimensions. The overlap between the GTV and the tumorH&E was calculated and the distance between the volumes was determined.


RESULTS
Tumor tissue was delineated in 203 of 516 H&E sections. For 14 patients a detailed analysis could be performed. The GTV volume was on average 1.7 times larger than the volume of the tumorH&E. The mean coverage of the tumorH&E by the consensus GTV was 88%. tumorH&E tissue was found at 1.6 mm to 12.9 mm distance outside the GTV depending on observer and patient.


CONCLUSIONS
GTVs delineated on CT for laryngeal and hypopharyngeal cancer were 1.7 times larger than the tumor. Complete coverage of the tumor by the GTV was, however, not obtained.
a Department of Radiotherapy , University Medical Center Utrecht , The Netherlands.
Joana
J
Caldas-Magalhaes
Nina
N
Kooij
Hans
H
Ligtenberg
Elise A
EA
Jager
Tim
T
Schakel
Nicolien
N
Kasperts
Frank A
FA
Pameijer
Chris H J
CH
Terhaard
Luuk M
LM
Janssen
Paul J
PJ
van Diest
Marielle E P
ME
Philippens
Cornelis P J
CP
Raaijmakers
D000368:Aged; D002294:Carcinoma, Squamous Cell / Q000000981:diagnostic imaging* / Q000473:pathology; D005260:Female; D006801:Humans; D007012:Hypopharyngeal Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology; D021621:Imaging, Three-Dimensional; D007822:Laryngeal Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology; D008297:Male; D008875:Middle Aged; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D014057:Tomography, X-Ray Computed; D047368:Tumor Burden