Objective: To evaluate the predictive value of FDG-PET/CT parameters on outcome of
oropharyngeal squamocellular cancer (OSCC) patients undergoing helical tomotherapy (HTT),
with dose escalation to FDG-PET/CT positive tumour volumes using the simultaneous integrated
boost (SIB) technique.
Materials and Methods: We analysed 41 patients studied by FDG-PET/CT and treated with radical
intent between 2005 and 2014 for OSCC. HTT-SIB was delivered in 30 fractions concomitantly:
69 Gy, as SIB, to the PET-positive volume (biological target volume – BTV-PET), both to
the primary tumour (T) and lymph nodes (N), 66 Gy to the T and positive N, 54 Gy to the laterocervical
nodes at risk. Selected PET parameters were recovered: maximum and mean standardized
uptake values (SUVmax and SUVmean, respectively), metabolic tumour volume (MTV) and total
lesion glycolysis (TLG) obtained with different thresholds (40-50-60% of the SUVmax) for T and
N. The correlation between these parameters and the 3-year overall (OS), cancer specific (CSS),
disease free (DFS), local relapse free for T and N (LRFS-T and LRFS-N) and distant metastasis
free (DMFS) survivals was investigated.
Results: The median follow-up was 37 months (range: 3-125). The 3-year OS, CSS, DFS, LRFST,
LRFS-N and DMFS were 86%, 88%, 76%, 83%, 88% and 91%, respectively. BTVT+
N>30.9cc and BTV-T>22.4cc were correlated with CSS (p=0.02) and OS (p=0.006) respectively;
TLG-T-60>34.6cc was correlated with CSS (p=0.04) and OS (p=0.01). MTV-T-60>4.4cc
could predict a higher risk of relapse/death (CSS: p=0.033; hazard ratio (HR) =10.92; OS: p=0.01;
HR=16.4; LRFS-T: p=0.02; HR=13.90; LRFS-T+N: p=0.03; HR=6.50).
Conclusion: PET parameters predicted survival outcomes and may be considered in the future in
the implementation of more personalized treatment schedules in patients affected by OSCC undergoing
radiotherapy. FDG-PET/CT dose escalated HTT-SIB allowed very promising 3-year disease
control rates in OSCC patients.