Table 3.

Prediction of progression-free survival (PFS), overall survival (OS), and clinical benefit (PFS > 6 months on endocrine therapy) by a 3-level classifier based on FDG and FES PET results (“Group”). This classifier was selected by recursive partitioning with fivefold internal cross-validation as the best predictor of PFS among patient (age) and clinical variables (PgR, number of lesions, visceral disease, number of prior chemotherapy regimens for metastatic disease), and imaging parameters (FES SULmean3, FES/FDG ratio, qualitative FES, and alternate summaries such as FES SUVmax3).

Group	N (PFS)	Median months PFS (95% confidence interval)	N (OS)	Median months OS (95% confidence interval)	PFS >6 months (95% confidence interval)
FDG SULmax3 < 2.2	24	26.1 (11.2 – 49.7)	24	69.5 (55.1 – NE)	18/21 = 86% (65%, 95%)
FDG SULmax3 ≥ 2.2 FES SULmean3 ≥ 0.85	50	7.9 (5.6 – 11.8)	53	41.9 (36.3 – 64.7)	27/46 = 59% (44%, 72%)
FDG SULmax3 ≥ 2.2 FES SULmean3 < 0.85	10	3.3 (1.4 - NE)	11	36.8 (22.1 – NE)	1/9 = 11% (1%, 43%)

N=88 for OS excludes 2 without FDG SULmax quantified

N=84 for PFS also excludes 4 without follow-up for progression

N=76 for clinical benefit also excludes 8 censored for progression before 6 months

FDG SULmax3 = geometric mean of FDG SULmax for 3 lesions in torso sweep with highest FDG SUVmax

FES SULmean = geometric mean of FES SULmean for 3 lesions in torso sweep with highest FDG SUVmax (see Table 1 footnotes)

NE = not evaluable