In this study, authors from multiple international centers address the question of AS vs. nephron-sparing surgery (NSS) for small renal masses and specifically look at competing risks of death. A purpose built a multi-institutional international database (REnal SURGery in the Elderly - RESURGE project) was used for this retrospective analysis.
Patients older than 75 years and presenting with a renal mass were treated between 2000 and 2016 at participating centers by NSS (i.e. partial nephrectomy or kidney ablation). A prospective registry of patients under AS for small renal mass (captured through the DISSRM study) was also included in the analysis and used as a comparative study group. A 1 to 2.2 matching was performed, which resulted in a total of 83 patients on AS and 186 on NSS. The variables included for matching were tumor size, clinical stage, Charlson Comorbidity Index, the presence of diabetes mellitus, hypertension and BMI and age. Cumulative incidence and competing for risk regression were used to estimate overall (OM) and other-cause mortality (OCM) rates.
Patient demographics are captured below:
The median follow-up was 34 months. Briefly, 50% of patients had tumors below 2 cm, 43% were older than 80 years old at diagnosis and over 70% had hypertension.
On multivariate Cox Regression Analysis, patients undergoing NSS were associated with lower rates of OCM (HR = 0.32; 95% CI (0.15-0.71); p = 0.045) and OM (HR = 0.41; 95% CI 0.21-0.83; p = 0.01). However, when you look at the KM curve below, you see that OM curves for AS and NSS essentially overlap until much later in the course – at 3-4 years is when the curve splits, barely. More importantly, based on patient censoring, the number of patients at risk that far out is relative. So, these results must be taken with caution.
On the cumulative incidence plot (seen below), a trend towards death by other cause was observed in both study groups.
The authors conclude that elderly patients with small renal masses undergoing NSS have better overall survival (though as we discussed earlier, this is a somewhat flawed statement based on patient data being censored), but this may be driven due to patient selection (as this is a retrospective study) and lower-rates of OCM (as cancer-specific mortality appeared to be equal).
Therefore, AS and NSS are both viable options and must be discussed with the patients.
Presented by: Maria C. Mir Maresma, MD, University of Miami Hospital, Miami, FL
Written by: Thenappan Chandrasekar, MD, Clinical Instructor, Thomas Jefferson University, @tchandra_uromd, @TjuUrology, at the 34th European Association of Urology (EAU 2019) #EAU19, conference in Barcelona, Spain, March 15-19, 2019.