Is there utility for fluorine-18-fluorodeoxyglucose positron-emission tomography scan before surgery in breast cancer? A 15-year overall survival analysis

Table 4 Multivariate models, original model with 5 years follow-up, vs current models with 15 yr follow-up

	Disease-free survival 5 yr of follow-up[6]		Disease-free survival 15 yr of follow-up, present study			Overall survival 15 yr of follow-up, present study
Variable	HR (95%CI)	R2N	HR (95%CI)	R2N	R2D	HR (95%CI)	R2N	R2D
PET axillary/sternal (positive vs negative)	2.81 (1.17, 6.74)	0.059	1.74 (0.96, 3.14)	0.030	0.053	3.08 (1.42, 6.69)	0.077	0.159
Age at diagnosis (yr)	1.05 (1.01, 1.09)	0.046	1.03 (1.00, 1.06)	0.047	0.075	1.06 (1.02, 1.10)	0.109	0.227
Adjuvant hormone therapy (yes vs no)	0.43 (0.16, 1.13)	0.030	0.51 (0.24, 1.08)	0.025	0.049	0.46 (0.18, 1.18)	0.020	0.083
Full model		NA		0.091	0.142		0.189	0.396

R2N and R2D values shown are the differences between the full model (computed with all three PET, age, adjuvant hormone therapy variables together) and the same full model without the variable. Higher values indicate higher importance of the variable in the model. Hazard ratios > 1 indicate increased risk of mortality. CI: Confidence interval; NA: Not available; HR: Hazard ratio; R2D: Royston-Sauerbrei index of prognostic separation; R2N: Nagelkerke proportion of explained variation.