Abstract: PD59-10
Sources of Funding: none

Introduction

Surgical intervention is the standard of care for large renal masses; however patients with competing risks may not be suitable candidates for immediate intervention. This study illustrates our experience with active surveillance (AS) and expectant management of large renal masses (LRM) ≥ 4cm. We describe the growth rate of LRM under surveillance, factors associated with growth rate, and overall outcomes.

Methods

Our institutional database identified 101 patients with renal masses ≥ 4.0cm between 1993 and 2016. Inclusion criteria were those followed with serial imaging for at least 6 months without surgical intervention. Bosniak 1-2 cysts and clinically benign renal masses such as angiomyolipomas were excluded from analysis. We used ordinal least squares regression to calculate LRM growth rate (cm/year) for each patient based on maximal diameter. Univariate linear regression was used to assess whether clinical factors were associated with growth rate and competing risk methods were used to estimate the probability of developing RCC metastasis in the setting of death from other causes.

Results

The median age at diagnosis was 73 (IQR 64, 80) with a median LRM size of 4.9cm (IQR 4.0, 6.7). Median follow up was 4 years (IQR 2.2, 7.3). Charlson comorbidity index was ≥2 in 59% of patients, and 32% had other non-renal malignancies. 19% of patients had or developed non-RCC metastasis from another malignancy. Median LRM growth rate was 0.4 cm/year (IQR 0.1, 0.8). We did not find a significant association between clinical factors and LRM growth. AS was discontinued in 34 patients who underwent surgical intervention after a median follow up of 1.9 years, 88% had malignant disease. Among 56 patients who underwent surgery or biopsy during AS, 82% had malignant histology. Median follow up for patients who did not undergo surgery was 3.3 years (IQR 1.9, 5.0). In total, 10 patients developed metastatic RCC (3 of whom died from RCC), and 29 patients died from other causes. Four treated patients progressed to RCC metastases, and 3 RCC-related mortality. Median follow up for metastasis free survivors was 4 years (IQR 2.2, 6.8). The 5-year probability of non-RCC related death and RCC metastasis was 26% and 7%, respectively.

Conclusions

In highly comorbid patients, such as those with other advanced malignancies, active surveillance and expectant management of LRM has a low likelihood for RCC progression which is overshadowed by the risk of non-RCC related death. This data supports the use of surveillance of LRM as an acceptable strategy for selected patients with competing risks from other serious illnesses.

Funding

none