3.2 The effect of body composition parameters on survival outcomes
The measured median PFS and OS times of all 108 patients with metastatic RCC were 11 (95% CI: 8-14) months and 46 (95% CI: 42.9-49.1) months, respectively. Among the obese (BMI≥30 kg/m2) and non-obese (BMI<30 kg/m2) patients, Kaplan–Meier analysis revealed a significant difference in the PFS (median 14 and 8 months, respectively, P= 0,039) while no significant difference was found in OS (median, 46 and 47 months, respectively, P=0,921) . The median PFS times for each IMDC risk groups were 21 months (favorable-risk group; 95% CI: 16.8–25.2), 14.0 months (intermediate-risk group; 95% CI: 11.9-16.1) and 6 months (poor-risk group; 95% CI 4.9-7.1). The median OS times for each risk group were 48 months (favorable-risk group; 95% CI: 46-50), and 46 months (intermediate-risk group; 95% CI: 43-49) and 28 months (poor risk; 95% CI: 25-32).
Using univariate Cox regression analyses as presented in Table 3, none of the body composition variables and their changes after 3-4 months of treatment initiation were associated with OS while SMI (HR: 0.979, 95% CI: 0.961–0.997, P=0.021) and psoas index (HR: 0.871, 95% CI: 0.776–0.978, P=0.020) were identified as the factors predicting better PFS. Multivariate Cox regression models have identified the independent prognostic factors for PFS and OS (Table 4). When adjusted by significant and potential variables in univariate analyses, only SMI was determined as an independent prognostic factor for PFS (HR: 0.975; 95% CI: 0.955–0.995, P=0.015). However, SMI was not found as a significant factor for OS. Although we found no association between VBC parameters or change in their values and OS according to univariate analyses; applying multivariate analyses, VATI (HR: 1.005; 95% CI: 1.001-1.009, P=0.024), SATI (HR: 0.976, 95% CI: 0.957-0.996, P=0.019) and TATI (HR: 0.982, 95% CI: 0.966-0.999, P=0.035) were determined as independent predictors for OS in addition to IMDC scoring system.