What is the best treatment approach for a solitary enhancing renal mass?

From the Guidelines

The best approach to treating a solitary enhancing kidney mass is partial nephrectomy for masses ≤7 cm, as it preserves kidney function while removing the tumor, as recommended by the most recent guidelines 1. When considering treatment options, several factors come into play, including the size of the mass, the patient's overall health, and the characteristics of the tumor.

• For small masses (less than 4 cm), partial nephrectomy is generally preferred as it preserves kidney function while removing the tumor, and this can be done through open surgery, laparoscopically, or with robotic assistance 1.
• For patients who are poor surgical candidates, ablative therapies such as radiofrequency ablation or cryoablation may be appropriate alternatives, with studies suggesting that ablation of small renal masses produces oncologic outcomes that approach those of surgical excision but with a significantly lower overall complication rate and a significantly lower decline in renal function 1.
• Larger masses (greater than 7 cm) typically require radical nephrectomy, removing the entire kidney, as minimally invasive radical nephrectomy is the preferred option for T2 tumors (>7 cm) 1.
• For masses between 4-7 cm, treatment decisions should be individualized based on tumor location and patient factors, and active surveillance might be considered for very small masses (less than 2 cm) in elderly patients with comorbidities 1. Before any treatment, a comprehensive evaluation including imaging (CT or MRI with contrast), assessment of kidney function, and sometimes biopsy is essential to characterize the mass, as up to 30% of small renal masses may be benign and may not require intervention 1. Treatment decisions should balance oncologic control with preservation of renal function, as chronic kidney disease can significantly impact long-term health outcomes, and a multidisciplinary discussion involving urologists, radiologists, and oncologists often provides the most comprehensive approach to these complex cases. Key considerations include:
• The role of surgery and local therapy, with partial nephrectomy being the preferred option for organ-confined tumors measuring ≤7 cm 1.
• The use of non-surgical options, such as radiofrequency ablation, stereotactic body radiotherapy, microwave ablation, and cryoablation, particularly in patients with small cortical tumors or those who are poor surgical candidates 1.
• The importance of active surveillance for small renal masses, with guidelines recommending repeat imaging in 3-6 months to assess for interval growth and consideration of renal mass biopsy for additional risk stratification 1.

From the Research

Treatment Options for Solitary Enhancing Kidney Mass

• Partial nephrectomy (PN) is a commonly used treatment for solitary enhancing kidney masses, with studies showing it to be a feasible and successful approach in most cases 2, 3, 4.
• Radical nephrectomy (RN) may be required in some cases, such as those with severe pre-existing chronic kidney disease (CKD) or overriding oncologic concerns 2, 5.
• Cryoablation (CA) and active surveillance (AS) are also options, although they are less commonly used 2.
• The use of tyrosine kinase inhibitors (TKIs) may facilitate PN in some cases, particularly those with clear-cell renal cell carcinoma and a high RENAL score 2.

Outcomes and Complications

• Studies have shown that PN can be performed safely in patients with a solitary kidney, with an acceptable decline in renal function and low likelihood of requiring temporary or permanent hemodialysis 3, 4.
• Perioperative complications, such as acute renal failure and urinary fistula, can occur, but are relatively rare 3, 4.
• The 5-year recurrence-free survival rates for PN, CA, and RN have been reported to be 83%, 80%, and 72%, respectively 2.

Considerations for Treatment

• The decision to perform PN or RN should be based on individual patient factors, such as tumor size, location, and complexity, as well as the patient's overall health and kidney function 5.
• Patients with a solitary kidney require regular and lifetime monitoring to detect any potential renal injury and to implement timely nephroprotective measures 6.