Identification of residual metabolic-active areas within individual NSCLC tumours using a pre-radiotherapy (18)Fluorodeoxyglucose-PET-CT scan.
OBJECTIVE
Non-small cell lung cancer (NSCLC) tumours are mostly heterogeneous. We hypothesized that areas within the tumour with a high pre-radiation (18)F-deoxyglucose (FDG) uptake, could identify residual metabolic-active areas, ultimately enabling selective-boosting of tumour sub-volumes.


METHODS
Fifty-five patients with inoperable stage I-III NSCLC treated with chemo-radiation or with radiotherapy alone were included. For each patient one pre-radiotherapy and one post-radiotherapy FDG-PET-CT scans were available. Twenty-two patients showing persistent FDG uptake in the primary tumour after radiotherapy were analyzed. Overlap fractions (OFs) were calculated between standardized uptake value (SUV) threshold-based auto-delineations on the pre- and post-radiotherapy scan.


RESULTS
Patients with residual metabolic-active areas within the tumour had a significantly worse survival compared to individuals with a complete metabolic response (p=0.002). The residual metabolic-active areas within the tumour largely corresponded (OF>70%) with the 50%SUV high FDG uptake area of the pre-radiotherapy scan. The hotspot within the residual area (90%SUV) was completely within the GTV (OF=100%), and had a high overlap with the pre-radiotherapy 50%SUV threshold (OF>84%).


CONCLUSIONS
The location of residual metabolic-active areas within the primary tumour after therapy corresponded with the original high FDG uptake areas pre-radiotherapy. Therefore, a single pre-treatment FDG-PET-CT scan allows for the identification of residual metabolic-active areas.
Aerts
Hugo J W L
HJ
Department of Radiation Oncology (MAASTRO), Grow-School for Oncology and Developmental Biology, Maastricht University, The Netherlands. Hugo.Aerts@maastro.nl
van Baardwijk
Angela A W
AA
Petit
Steven F
SF
Offermann
Claudia
C
Loon
Judith van
Jv
Houben
Ruud
R
Dingemans
Anne-Marie C
AM
Wanders
Rinus
R
Boersma
Liesbeth
L
Borger
Jacques
J
Bootsma
Gerben
G
Geraedts
Wiel
W
Pitz
Cordula
C
Simons
Jean
J
Wouters
Bradly G
BG
Oellers
Michel
M
Lambin
Philippe
P
Bosmans
Geert
G
Dekker
Andre L A J
AL
De Ruysscher
Dirk
D