Table 3.
Cox regression analyses assessing the effect of PET/CT metrics on OS (N=138)
| Variable | Unit/Cutpoint categories | HR (95%CI) | P | AIC | IAUC | |
|---|---|---|---|---|---|---|
| Univariable models | ||||||
| SUVmax | 1-unit increase | 1.019 (1.003, 1.034) | 0.016 | 808.6 | 0.605 | |
| Log2 MTV | 1-unit increase | 1.36 (1.24, 1.49) | <.0001 | 764.8 | 0.836 | |
| Log2 TLG | 1-unit increase | 1.30 (1.19, 1.41) | <.0001 | 769.9 | 0.822 | |
| SDmax (N=106) | 1-unit increase | 1.002 (1.001, 1.004) | 0.003 | 585.9 | 0.645 | |
| SDmax bulk (N=106) | 1-unit increase | 1.002 (1.001, 1.004) | 0.008 | 587.4 | 0.631 | |
| Age | 1-unit increase | 1.00 (0.99, 1.02) | 0.972 | 814.0 | 0.498 | |
| IMPI | 1-unit increase | 3.16 (2.23, 4.47) | <.0001 | 774.8 | 0.799 | |
| SUVmax | ≥18 vs <18 | 1.72 (1.10, 2.69) | 0.017 | 807.9 | 0.613 | |
| MTV | ≥96 vs <96 | 3.56 (2.26, 5.60) | <.0001 | 780.7 | 0.732 | |
| TLG | ≥926 vs <926 | 3.34 (2.14, 5.21) | <.0001 | 783.3 | 0.728 | |
| SDmax (N=106) | ≥225 vs <225 | 1.87 (1.18, 2.98) | 0.008 | 587.1 | 0.608 | |
| SDmax bulk (N=106) | ≥206 vs <206 | 1.93 (1.21, 3.07) | 0.006 | 586.4 | 0.611 | |
| LDH | High vs normal | 2.98 (1.81, 4.91) | <.0001 | 792.2 | 0.667 | |
| Stage | III-IV vs I-II | 1.32 (0.81, 2.14) | 0.268 | 812.7 | 0.542 | |
| Age | ≥60 vs <60 | 1.05 (0.68, 1.60) | 0.837 | 813.9 | 0.504 | |
| IMPI | ≥1.25 vs <1.25 | 3.53 (2.29, 5.43) | <.0001 | 779.9 | 0.746 | |
| Multivariable models: | P | AIC | IAUC | IAUC change | ||
| Model 1: | ||||||
| MTV | ≥96 vs <96 | 3.09 (1.84, 5.17) | <.0001 | 777.1 | 0.773 | 0.041 |
| LDH | High vs normal | 2.10 (1.24, 3.56) | 0.006 | -- | -- | -- |
| Stage | III-IV vs I-II | 0.81 (0.47, 1.38) | 0.428 | -- | -- | -- |
| Age | ≥60 vs <60 | 1.14 (0.74, 1.76) | 0.555 | -- | -- | -- |
| Model 2: | ||||||
| MTV | ≥96 vs <96 | 3.75 (1.90, 7.40) | 0.0001 | 558.2 | 0.796 | 0.090* |
| SDmax (N=106) | ≥225 vs <225 | 1.48 (0.88, 2.48) | 0.142 | -- | -- | -- |
| LDH | High vs normal | 2.40 (1.27, 4.55) | 0.007 | -- | -- | -- |
| Stage | III-IV vs I-II | 0.64 (0.31, 1.35) | 0.242 | -- | -- | -- |
| Age | ≥60 vs <60 | 0.88 (0.53, 1.45) | 0.608 | -- | -- | -- |
| Model 3: | ||||||
| MTV | ≥96 vs <96 | 3.29 (1.90, 5.67) | <.0001 | 776.5 | 0.764 | 0.032 |
| SUVmax | ≥18 vs <18 | 0.74 (0.44, 1.25) | 0.266 | -- | -- | -- |
| LDH | High vs normal | 2.21 (1.30, 3.77) | 0.003 | -- | -- | -- |
| Age | ≥60 vs <60 | 1.13 (0.73, 1.73) | 0.585 | -- | -- | -- |
HR: Hazard ratio of death for 1-unit increase, and for comparing groups variable ≥cutpoint versus <cutpoint (ref). The cutpoints for PFS were used for OS. CI: confidence interval. P: p-value testing HR=1 from Wald test.
AIC: Akaike information criterion (smaller is better model fit). IAUC: Integrated area under the ROC curve, computed as a weighted average of the AUC values at all the event times (higher is better model prediction). IAUC change: change in IAUC between multivariable and univariable model using dichotomized MTV in N=138 or N=106 (*).
Abbreviations; SUVmax, maximum standardized uptake value; MTV, metabolic tumor volume, TLG, tumor lesion glycolysis; SDmax, largest distance between two lesions that are farthest apart; IMPI, International Metabolic Prognostic Index; LDH, lactate dehydrogenase