Table 2.

Univariate analysis of patient-level and voxel-level forecasting of mid-RT PET SUV

Univariate model
Patient/tumor variableβa (95% CI)P valuec
Female sex1.2 (−26.5, 39.5)0.94
Age, per 5-y increase4.3 (−9.6, 20.5)0.55
Adenocarcinoma (vs. squamous cell carcinoma)−6.0 (−40.8, 49.2)0.78
Stage IIIB (vs. other)33.4 (−2.9, 83.2)0.073
Proton beam therapy (vs. X-ray radiotherapy)−10.8 (−35.2, 22.8)0.47
Chemotherapy modality
 Carboplatin + paclitaxel(ref)
 Cisplatin + etoposide1.2 (−27.2, 40.9)0.94
Primary metabolic tumor volume (MTV)b, per 50% increase−0.4 (−4.8, 4.1)0.85
Primary SUVmaxb, per 50% increase18.1 (6.0, 31.7)0.004
Primary SUVmeanb, per 50% increase20.0 (6.9, 34.8)0.003
Primary total lesion glycolysis (TLG)b, per 50% increase1.3 (−2.5, 5.3)0.48
Ring/concave uptake pattern (vs. foci/convex)−1.9 (−28.5, 34.8)0.90
Time from pre-RT PET to mid-RT PET, per 1-wk increase−4.2 (−14.6, 7.5)0.45
Time from pre-RT PET to RT start, per 1-wk increase−4.3 (−14.8, 7.5)0.44
No. of RT fractions between pre-RT and mid-RT PET1.6 (−14.5, 20.7)0.85
Mean dose between pre-RT and mid-RT PET, per 1-Gy increase0.7 (−6.4, 8.3)0.84
Voxel variable
 Voxel pre-RT SUVb, per 50% increase34.6 (27.1, 42.6)<0.001
 Voxel RT dose, per 1-Gy increase−2.7 (−11.3, 6.9)0.56
 Voxel distance from tumor centroid, per 1-cm increase−7.4 (−23.5, 12.0)0.41
  • aPercent change in average SUV at the mid-RT PET scan.

  • bThe predictor was log-transformed prior to inclusion in the model to reduce right skewness.

  • cBoldfaced values indicate statistical significance (P < 0.05).