Small renal masses (SRMs) are common incidental findings on imaging.¹ There are many considerations in the evaluation and management of SRMs which include mass characteristics (size, location, appearance on imaging), patient characteristics (age/life expectancy, comorbidities such as suitability for surgery, and renal function) and patient preferences.^2,3 The AUA guidelines offer broad recommendations covering use of cross-sectional imaging, role of biopsy, and consideration of different approaches to management which include active surveillance (AS), ablation, partial nephrectomy (PN), and radical nephrectomy (RN). On the other hand, the guidelines do not directly consider the financial implications of these decisions on the patient or health care system. Each step of evaluation and management and surveillance is associated with different financial impacts.

In terms of evaluation, it is important to recognize that approximately 25% of SRMs are benign.⁴ The guidelines recommend counseling patients on utility of renal mass biopsy (RMB) and a meta-analysis found that RMB has a high sensitivity (97%), specificity (94%), and positive predictive value (99%), but a nondiagnostic rate of 14% affects the frequency of clinical utilization.⁵ Furthermore, there are risks of complications such as gross hematuria (1.0%), pneumothorax (0.6%), and hemorrhage requiring transfusion (0.4%). In one study, the total costs of RMB including facility costs, pathology fees, and professional fees ranged from $2,129 for office-based approaches to $4,598 for hospital biopsies⁶; however, these costs need to be balanced against the cost savings of avoiding treatment and lower intensity surveillance for those patients with negative biopsies and possibly low-grade tumors. There is also an evolving role for use of the clear cell likelihood score (ccLS) to classify clear cell renal carcinoma noninvasively by using multiparametric MRI.¹ In a retrospective multicenter cross-sectional study with 241 patients, the sensitivity, specificity, and positive predictive value for the diagnosis of clear cell renal carcinoma when ccLS was 4 or higher were 75% (95% CI: 68, 81), 78% (72, 84), and 76% (69, 81), respectively. The negative predictive value of a ccLS of 2 or lower was 88% (95% CI: 81, 93). This approach may save costs by avoiding unnecessary treatment, but further data will be needed to assess the cost of possible progression in patients with false-negative findings.

Decisions regarding treatment as compared with AS have the greatest implications on cost. The guidelines recommend AS/expectant management when the anticipated risk of intervention or competing risks of death outweigh the potential oncologic benefits of active treatment, and treatment when risk of cancer outweighs risk of death from other causes.³ The challenge is in patients with equivocal benefit where the guidelines recommend considering an RMB and close imaging. The cost implications are primarily based on how frequently imaging is utilized, whether RMB is used to make this decision, and what percent of patients subsequently undergo treatment or potentially progress with the ensuing costs associated with metastatic disease. Interestingly, one of the guideline recommendations for future directions of developing markers to identify patients for AS may actually increase the cost of managing tumors based on added cost of the markers.

In patients where treatment is recommended, there are multiple options including ablation (radiofrequency, cryotherapy) and surgery, which can be done open, laparoscopic, or robotic-assisted and include PN and RN. The guidelines recommend that clinicians should prioritize PN for the management of SRMs in order to preserve nephrons and due to equivalent cancer outcomes compared with RN.² However, PN is associated with higher short-term complication rates, with potential cost implications, and PN is not always feasible based on tumor size and location. The guidelines support the use of ablation as an alternative approach for managing SRMs ≤3 cm. A meta-analysis evaluating AS, thermal ablation, and RN or PN found that cancer-specific survival was excellent for all approaches (median 5-year survival 95%); however, local recurrence-free survival was inferior for ablation with 1 treatment but reached equivalence if repeat ablation was included.⁷ Overall survival rates did not differ among treatments. While RN resulted in the greatest decrease in glomerular filtration rate and higher rate of chronic kidney disease, end-stage renal disease rates were low for all strategies (0.4% to 2.8%). Ablation had the best perioperative outcomes while PN showed the highest rates of urological complications.

Evaluating the cost implications can be challenging since there are no randomized trials and there is considerable selection bias in selecting approaches such as AS when compared to treatment. There are significant cost implications unrelated to the renal mass when considering patient comorbidities and other cause mortality. Patients with significant comorbidities are also more likely to have complications with treatment, which can significantly increase cost. Biopsy and surveillance could help avoid cost of treatment-related complications in these patients. Patients who undergo AS and ablation are often older and sicker than those who undergo active treatment. If one performs direct comparisons of similar treatments like open, laparoscopic, and robotic approaches, factors such as inflation need to be considered since laparoscopic series are typically older than robotic series. A meta-analysis comparing cost of robotic, laparoscopic, and open PN found that the laparoscopic approach was the most cost-effective at a mean direct cost of $10,311, with a cost advantage of $1,116 and $1,652 over open ($11,427) and robotic assisted ($11,962), respectively.⁸ A practical question is how well current urologists are trained in laparoscopic approaches and whether reduced operative times would mitigate some of the added costs of using a robot in contemporary practice. Patients with significant comorbidities are also more likely to have complications with treatment, which can significantly increase cost. Biopsy and surveillance could help avoid cost of treatment-related complications in these patients.

There are conflicting analyses on the most cost-effective method for approaching SRMs. One group used a Markov model to estimate optimal management of a SRM in a healthy 65-year-old patient.⁹ They found that observation was least costly but immediate laparoscopic PN was most cost-effective in terms of quality adjusted life-years gained compared to surveillance with possible delayed percutaneous ablation. Not surprisingly, the results depended on age, health status, and tumor size since observation was favored in poor surgical candidates or those with limited life expectancy. A different study found that immediate ablation was preferred to nephron-sparing surgery but depended on a low probability of post-ablation recurrence.¹⁰

A more recent Markov model estimated the health outcomes and costs of 4 management strategies for 65-year-old patients with an incidental SRM.¹¹ Their model found a 10-year all-cause mortality of 21.9% for immediate PN, 22.4% for immediate RN, 22.6% for AS, and 23.7% for immediate thermal ablation. Surveillance was the most cost-effective management strategy since annual probability of metastatic progression from AS was low (under 0.35%-0.45% for most ages at baseline) and had the highest quality of life.

Currently, cost is not a criterion used in the guidelines to make treatment recommendations. However, with an aging population and improved imaging, the rate of SRMs is likely to increase. As such, the economic burden of managing these masses will likely increase. It is important to continue to consider the financial impact of treatment decisions with the goal of optimizing not only patient care but also reducing health care costs. Financial toxicity can apply to both the health system as well as the patient and can be particularly impactful if there are treatments being done for benign or indolent disease, especially in patients with comorbidities who are at increased risk of complications.