Introduction

Approximately 15-20% of incidental renal masses ≤4cm are benign including oncocytomas and lipid poor angiomyolipomas (AML), which can be managed non-surgically. Increasing utilization of small renal mass biopsy (SRMB) may decrease upfront costs and preserving renal function in untreated patients. The objective of this study is to evaluate if increasing biopsy utilization reduces surgical treatment and upfront (30 day) costs for patients with small renal masses (SRM).

Methods

Clinical and pathologic data were reviewed from patients with incidental SRM who were treated surgically and/or received SRMB from 2003-2015. Patients not considering surgery were excluded. Patients were divided into 2 cohorts (2003-2009 and 2010-2015) for analysis based on increased SRMB utilization at our institution. 2015 Medicare costs were used to calculate comprehensive costs of surgery and biopsy for 30 days following surgery.

Results

Of 437 patients with renal masses ≤4cm, SRMB was performed in 6% of 199 patients treated from 2003-2009 and 54% of 238 patients from 2010-2015. The rate of surgery for benign tumors from 2003-2009 was higher than 2010-2015, 19.7% vs. 12.3%, p=0.04. _x000D_ _x000D_ In patients treated without biopsy from 2010-2015, benign surgery rate was 21.8%. From 2010-2015, 42 patients with benign tumors were identified using SRMB and avoided surgery (10 AML, 32 oncocytoma). _x000D_ _x000D_ Given the upfront cost of $2,020.44 USD for ultrasound guided biopsy and $12,153.01 USD for partial nephrectomy, cost of care per patient were calculated each two cohorts. _x000D_ _x000D_ The cost per patient in the 2003-2009 vs. 2010-2015 cohort was $12,274.85 USD vs. $11,094.98 USD. Increased biopsy utilization was associated with $1,179.86 (9.6%) cost savings per patient. For 2010-2015, increased use of biopsy saved $280,840 USD in estimated upfront treatment costs. _x000D_

Conclusions

Pretreatment biopsy for renal masses ≤ 4cm reduces surgery for benign tumors and subsequently decreases the upfront cost of care per SRM patient by $1,179.86 USD.

Funding

NIH T35DK062709-11