Renal mass biopsy to guide treatment decisions for small incidental renal tumors: a cost-effectiveness analysis

Abstract

Purpose: To evaluate the effectiveness, cost, and cost-effectiveness of using renal mass biopsy to guide treatment decisions for small incidentally detected renal tumors.

Materials and methods: A decision-analytic Markov model was developed to estimate life expectancy and lifetime costs for patients with small (< or = 4-cm) renal tumors. Two strategies were compared: renal mass biopsy to triage patients to surgery or imaging surveillance and empiric nephron-sparing surgery. The model incorporated biopsy performance, the probability of track seeding with malignant cells, the prevalence and growth of benign and malignant tumors, treatment effectiveness and costs, and patient outcomes. An incremental cost-effectiveness analysis was performed to identify strategy preference under a willingness-to-pay threshold of $75,000 per quality-adjusted life-year (QALY). Effects of changes in key parameters on strategy preference were evaluated in sensitivity analysis.

Results: Under base-case assumptions, the biopsy strategy yielded a minimally greater quality-adjusted life expectancy (4 days) than did empiric surgery at a lower lifetime cost ($3466), dominating surgery from a cost-effectiveness perspective. Over the majority of parameter ranges tested in one-way sensitivity analysis, the biopsy strategy dominated surgery or was cost-effective relative to surgery based on a $75,000-per-QALY willingness-to-pay threshold. In two-way sensitivity analysis, surgery yielded greater life expectancy when the prevalence of malignancy and propensity for biopsy-negative cancers to metastasize were both higher than expected or when the sensitivity and specificity of biopsy were both lower than expected.

Conclusion: The use of biopsy to guide treatment decisions for small incidentally detected renal tumors is cost-effective and can prevent unnecessary surgery in many cases.

Figure 1:

Simplified schematic of decision model. Two management strategies were considered for initial management of an imaging-detected tumor: renal mass biopsy or empiric NSS. This schematic demonstrates how the consequences of opting for one strategy over another were modeled in our analysis. CT = computed tomography.

Figure 2:

Plot of two-way sensitivity analysis of biopsy sensitivity and specificity. When biopsy sensitivity and specificity are high, as is typical (BCE: sensitivity, 90%; specificity, 100%), the biopsy strategy provides greater life expectancy (green). Blue = empiric NSS provides greater life expenctancy.

Figure 3:

Plot of two-way sensitivity analysis of parameters that determine tumor aggressiveness. Biopsy yields a greater life expectancy (green) over most of the parameter space tested. When tumors are assigned more aggressive features (ie, higher prevalence of malignancy and propensity to metastasize) than would be typically expected (BCE: yearly probability of metastasis for a biopsy-negative RCC, 0.012; prevalence of RCC among tumors, 0.77), then empiric NSS yields a greater life expectancy (blue).