Prognostic utility of (18)F-FDG PET-CT performed prior to and during primary radiotherapy for nasopharyngeal carcinoma: Index node is a useful prognostic imaging biomarker site.
To evaluate the prognostic value of (18)F-FDG-PET-CT performed prior to (prePET) and during the third week (iPET) of radiation therapy (RT) in nasopharyngeal carcinoma (NPC).



Thirty-patients with newly diagnosed loco-regionally advanced NPC treated with radical RT underwent prePET and iPET. The median follow-up was 26months (8-66.9). The maximum-standardised-uptake-value (SUVmax), metabolic-tumour-volume (MTV) and total-lesional-glycolysis (TLG) of the primary tumour (PT), index-node (IN) (lymph node with highest TLG), total-lymph-nodes (TN) and combined primary-tumour and nodal (PTN), and their % reductions in iPET were analysed, and results were correlated with 2-year Kaplan-Meier loco-recurrence-free-survival (LRFS), regional-failure-free-survival (RFFS), distant-metastatic-failure-free-survival (DMFFS), disease-free-survival (DFS), and overall-survival (OS). Optimal-cutoffs (OC) were derived from Receiver-Operating-Characteristic curves.



For LRFS, the only predictor was reduction in PT MTV by >50%: 95.2% vs. 75.0%, p=0.024. For other treatment outcomes, only nodal or PTN predicted outcomes. The IN SUVmax (pre-PET-OC=10.45g/mL and iPET-OC=8.15) and TLG (prePET-OC=90g and iPET-OC=33.4) were the best predictors of outcome: RFFS (iPET SUVmax/TLG): 100% vs. 50%, p<0.001 and 100% vs. 44%, p=0.032; DMFFS (prePET SUVmax/TLG); 100% vs. 51.9%, p=0.004 and 100% vs. 47.6%, p=0.002; DFS (prePET TLG and iPET SUVmax): 87.5% vs. 33%, p=0.045 and 78.7% vs. 20%, p=0.01; and OS (prePET TLG): 100% vs 66.3%, p=0.036.



We have demonstrated IN of prePET and iPET to be a feasible and potentially useful novel imaging biomarker to predict for patients with NPC who have a high risk of regional or distant metastatic failure. Future work is required to validate our findings in a well-powered, prospective study with a standardised treatment protocol, and their potential use to guide individualised therapy for NPC.
Department of Nuclear Medicine and PET, Liverpool Hospital, Australia; South Western Sydney Clinical School, University of New South Wales, Australia; University of Western Sydney, Australia. Electronic address: peter.lin@sswahs.nsw.gov.au.
Peter
P
Lin
South Western Sydney Clinical School, University of New South Wales, Australia; Cancer Therapy Centre, Liverpool Hospital, Australia; Ingham Institute of Applied Medical Research, Liverpool, Australia.
Myo
M
Min
South Western Sydney Clinical School, University of New South Wales, Australia; Cancer Therapy Centre, Liverpool Hospital, Australia.
Mark
M
Lee
South Western Sydney Clinical School, University of New South Wales, Australia; University of Western Sydney, Australia; Cancer Therapy Centre, Liverpool Hospital, Australia; Ingham Institute of Applied Medical Research, Liverpool, Australia.
Lois
L
Holloway
South Western Sydney Clinical School, University of New South Wales, Australia; Cancer Therapy Centre, Liverpool Hospital, Australia; Ingham Institute of Applied Medical Research, Liverpool, Australia.
Dion
D
Forstner
Cancer Therapy Centre, Liverpool Hospital, Australia.
Victoria
V
Bray
Ingham Institute of Applied Medical Research, Liverpool, Australia.
Wei
W
Xuan
Department of Nuclear Medicine and PET, Liverpool Hospital, Australia.
Andrew
A
Chicco
Cancer Therapy Centre, Liverpool Hospital, Australia.
Allan
A
Fowler
D000328:Adult; D000368:Aged; D015415:Biomarkers / Q000378:metabolism; D002277:Carcinoma / Q000000981:diagnostic imaging / Q000401:mortality / Q000532:radiotherapy*; D018572:Disease-Free Survival; D005260:Female; D019788:Fluorodeoxyglucose F18; D006019:Glycolysis; D006801:Humans; D008297:Male; D008875:Middle Aged; D000077274:Nasopharyngeal Carcinoma; D009303:Nasopharyngeal Neoplasms / Q000000981:diagnostic imaging / Q000401:mortality / Q000532:radiotherapy*; D000072078:Positron Emission Tomography Computed Tomography / Q000379:methods*; D011379:Prognosis; D019275:Radiopharmaceuticals
D015415:Biomarkers; D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18
Adaptive radiotherapy; FDG; Imaging biomarker; Nasopharyngeal carcinoma; PET CT; Positron emission tomography; Prognostic value