Short summary

CT-guided percutaneous cryoablation (PCA) is a minimally invasive of renal cancer proved to be efficient with outcome comparable to surgery. The aim of this study is to evaluate the outcome of patients treated with minimally invasive, nephron sparing treatments of small renal cell carcinomas (RCC) at Odense University Hospital (OUH). We expect to include 80 patients treated with PCA and 80 patients treated with partial nephrectomy. 

Rationale

Over the last 20 years, the annual detection of presumably treatable benign and malignant small renal tumors ? 4 cm has increased continuously worldwide. More than 50% of renal cancer are reported as incidental findings. In 2015, 900 new renal cancer were diagnosed in Denmark, accounting for 3-4% of all newly diagnosed malignancies in adults with approximately 300 deaths per year. Presently, it is not possible to predict which renal tumors have a fatal or indolent course. Worldwide, rates of surgery for renal tumors have increased in the last decades with no reduction in mortality rates despite early tumor detection (1).

Traditionally, surgical management has been the preferred treatment for solid renal masses. Nephron-sparing ablative techniques were introduced 10-15 years ago, initially reserved for fragile patients. However, indications for thermal ablations have expanded, now including younger and otherwise healthy patients. Thus, nephron sparing treatment, e.g. percutaneous cryoablation (PCA) and partial nephrectomy (PN) are prioritized. During PCA, the patient is placed in a prone position in a Computed Tomography (CT) scanner for monitoring of the procedure. The cryoprobes create an expanding ice ball that surrounds the tumor and destroy the cancer cells. Residual tumor, also termed incomplete ablation, is defined as unsuccessful treatment detected ? 3 months after the treatment and is seen in 2-8% in the literature. Residual tumors re-treated with cryoablation have an almost 100% success rate. 

Three-year cancer free survival for patients with T1a tumors treated with PCA versus PN has proved to be similar (98-100%). Long-time outcome after PCA is not yet scientifically determined. However, PCA has several advantages, including shorter recovery time, less pain and lower frequency of medically significant complications. Furthermore, no general anesthesia is required allowing inclusion of comorbid patients, and the possibility of performing the procedure in an outpatient setting. This leads to PCA being approximately 50% cheaper than ordinary surgery. The changes in renal function and volume following PCA remain poorly studied. 

Preservation of renal function is crucial in the management of patients diagnosed with renal cancer. Impaired renal function is associated with an increased risk of cardiovascular disease, hospitalization and mortality. Nephron sparing treatments are believed to have minimal influence on renal function. The advantage of PCA regarding renal function still remains unclear. In literature, results after laparoscopic and percutaneous cryoablation are not differentiated, which could be considered a significant bias.

Preservation of renal function is one of many reasons why nephron sparing treatments are becoming increasingly preferred in treating renal cancer, although this claim has yet to be scientifically confirmed.

Purpose: 

To evaluate the effect of nephron sparing treatment of renal cancer, regarding: 

• Renal function
• Oncological outcome

Description of the cohort

The population consists of patients with biopsy verified renal cancer. Otherwise, included patients can be otherwise healthy, comorbid, or with renal impairment. 

Data and biological material

Journal data, results from standard laboratory tests and imaging details are collected. The patients will undergo renal functional examinations (renal clearance and renography) in the Department of Nuclear Medicine.  

Collaborating researchers and departments

Department of Radiology, Odense University Hospital

• Associate professor Ole Graumann, MD, PhD 
• Benjamin Rasmussen, MD, PhD

Department of Urology, Odense University Hospital

• Professor Lars Lund

Department of Nuclear Medicine, Odense Universtity Hospital

Comparative Medicine Lab, Institute of Clinical Medicine, Skejby Hospital

• Professor Michael Pedersen