Can adaptive threshold-based metabolic tumor volume (MTV) and lean body mass corrected standard uptake value (SUL) predict prognosis in head and neck cancer patients treated with definitive radiotherapy/chemoradiotherapy?
OBJECTIVE
To evaluate the predictive value of adaptive threshold-based metabolic tumor volume (MTV), maximum standardized uptake value (SUVmax) and maximum lean body mass corrected SUV (SULmax) measured on pretreatment positron emission tomography and computed tomography (PET/CT) imaging in head and neck cancer patients treated with definitive radiotherapy/chemoradiotherapy.


METHODS
Pretreatment PET/CT of the 62 patients with locally advanced head and neck cancer who were treated consecutively between May 2010 and February 2013 were reviewed retrospectively. The maximum FDG uptake of the primary tumor was defined according to SUVmax and SULmax. Multiple threshold levels between 60% and 10% of the SUVmax and SULmax were tested with intervals of 5% to 10% in order to define the most suitable threshold value for the metabolic activity of each patient's tumor (adaptive threshold). MTV was calculated according to this value. We evaluated the relationship of mean values of MTV, SUVmax and SULmax with treatment response, local recurrence, distant metastasis and disease-related death. Receiver-operating characteristic (ROC) curve analysis was done to obtain optimal predictive cut-off values for MTV and SULmax which were found to have a predictive value. Local recurrence-free (LRFS), disease-free (DFS) and overall survival (OS) were examined according to these cut-offs.


RESULTS
Forty six patients had complete response, 15 had partial response, and 1 had stable disease 6 weeks after the completion of treatment. Median follow-up of the entire cohort was 18 months. Of 46 complete responders 10 had local recurrence, and of 16 partial or no responders 10 had local progression. Eighteen patients died. Adaptive threshold-based MTV had significant predictive value for treatment response (p=0.011), local recurrence/progression (p=0.050), and disease-related death (p=0.024). SULmax had a predictive value for local recurrence/progression (p=0.030). ROC curves analysis revealed a cut-off value of 14.00 mL for MTV and 10.15 for SULmax. Three-year LRFS and DFS rates were significantly lower in patients with MTV ≥ 14.00 mL (p=0.026, p=0.018 respectively), and SULmax≥10.15 (p=0.017, p=0.022 respectively). SULmax did not have a significant predictive value for OS whereas MTV had (p=0.025).


CONCLUSIONS
Adaptive threshold-based MTV and SULmax could have a role in predicting local control and survival in head and neck cancer patients.
Ege University Faculty of Medicine Department of Radiation Oncology, 35100, Bornova, Izmir, Turkey. Electronic address: o_akagunduz@yahoo.com.
Ozlem Ozkaya
OO
Akagunduz
Ege University Faculty of Medicine Department of Radiation Oncology, 35100, Bornova, Izmir, Turkey.
Recep
R
Savas
Ege University Faculty of Medicine Department of Radiation Oncology, 35100, Bornova, Izmir, Turkey.
Deniz
D
Yalman
Ege-Rad Imaging Center, Department of Nuclear Medicine, 35100, Ankara Cad. 243/A, Bornova, Izmir, Turkey.
Kenan
K
Kocacelebi
Ege University Faculty of Medicine Department of Radiation Oncology, 35100, Bornova, Izmir, Turkey.
Mustafa
M
Esassolak
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001692:Biological Transport; D015992:Body Mass Index; D059248:Chemoradiotherapy; D018572:Disease-Free Survival; D005260:Female; D006258:Head and Neck Neoplasms / Q000175:diagnosis* / Q000473:pathology / Q000532:radiotherapy / Q000628:therapy*; D006801:Humans; D008297:Male; D008875:Middle Aged; D049268:Positron-Emission Tomography; D011379:Prognosis; D014057:Tomography, X-Ray Computed; D047368:Tumor Burden; D055815:Young Adult
Adaptive threshold-based metabolic tumor volume (MTV); Chemoradiotherapy; Head and neck cancer; Lean body mass corrected standard uptake value (SUL); Radiotherapy