Use of surveillance imaging following treatment of small renal masses

Abstract

Purpose: With the increasing incidence of small renal masses, there is greater use of ablation, nephron sparing surgery and surveillance compared to radical nephrectomy. However, patterns of care in the use of posttreatment imaging remain uncharacterized. The purpose of this study is to determine the rate of posttreatment imaging after various treatments for small renal mass.

Materials and methods: Using SEER (Surveillance, Epidemiology and End Results)-Medicare data during 2005 to 2009, we identified 1,682 subjects diagnosed with small renal mass and treated with open partial nephrectomy (330), minimally invasive partial nephrectomy (160), open radical nephrectomy (404), minimally invasive radical nephrectomy (535), thermal ablation (212) and surveillance (42). Use of imaging was compared within 24 months of treatment and multivariate regression models were constructed to identify factors associated with increased imaging use.

Results: On adjusted analyses thermal ablation was associated with almost eightfold greater odds of surveillance imaging compared with open radical nephrectomy (OR 7.7, 95% CI 1.01-59.4). Specifically, thermal ablation was associated with increased computerized tomography (OR 5.28) and magnetic resonance imaging (OR 2.19) use and decreased ultrasound use (OR 0.59). Minimally invasive partial nephrectomy (OR 3.28) and open partial nephrectomy (OR 3.19) were also associated with increased computerized tomography use to a lesser extent.

Conclusions: Subjects undergoing nephron sparing surgery undergo more posttreatment imaging compared to open radical nephrectomy. Although possibly associated with lower morbidity, thermal ablation is associated with significantly greater use of imaging compared to other small renal mass treatments. This may increase costs and radiation exposure, although further study is needed for confirmation.

Keywords: CT; MIPN; MIRN; MRI; NSS; OPN; ORN; PN; RCC; RFA; RN; SRM; TA; UCLA Integrated Scoring System; UISS; ablation techniques; computerized tomography; kidney neoplasms; magnetic resonance imaging; minimally invasive partial nephrectomy; minimally invasive radical nephrectomy; nephron sparing surgery; open partial nephrectomy; open radical nephrectomy; partial nephrectomy; radical nephrectomy; radio frequency ablation; renal cell carcinoma; small renal mass; thermal ablation.