Percutaneous radiofrequency ablation for renal cancer

There are few symptoms in the early stages of renal cancer. Typically, symptoms develop as the disease progresses. The first symptom is often blood in the urine; pain and flank mass are other classic symptoms.

Renal cancer may be diagnosed incidentally on imaging studies or patients may present with symptoms. Conventional treatment for renal cancer is total or partial nephrectomy (open or laparoscopic). One of a range of non-resectional ablative procedures such as cryoablation and radiofrequency ablation (RFA) may be selected for some smaller tumours.

Percutaneous RFA for renal cancer is carried out with the patient under either local anaesthesia and sedation or general anaesthesia. Hydrodisplacement may be used to displace the bowel away from the tumour. One or more radiofrequency electrodes are inserted percutaneously into the tumour under imaging guidance. Radiofrequency energy is delivered via the electrode(s) to coagulate and destroy the tumour tissue in the target area. The procedure can be repeated if necessary.

A meta-analysis of 47 studies (non-randomised comparative studies and case series) including a total of 1,375 tumours treated by RFA (n=775) or cryoablation (n=600) reported local tumour progression (defined as radiographic or pathological evidence of residual disease after initial treatment, regardless of time to recurrence) in 13% (100 of 775) and 5% (31 of 600) of tumours respectively at a mean 19-month follow-up (p<0.001). The meta-analysis reported progression to metastatic disease in 2% (19 of 775) of tumours treated by RFA and 1% (6 of 600) of tumours treated by cryoablation (p=not significant).

In a non-randomised comparative study of 233 patients (260 tumours), residual or recurrent tumour on follow-up MRI was reported in 11% (9 of 81) of tumours treated by percutaneous RFA and 2% (3 of 179) of tumours treated by laparoscopic cryotherapy (1-year and 3-year median follow-up respectively).

A non-randomised comparative study of 264 patients (301 tumours) reported radiographic success (defined as no evidence of central or nodular enhancement after treatment) in 85% (62 of 73) of patients treated by percutaneous RFA and 90% (125 of 139) of patients treated by laparoscopic cryoablation at 6-month follow-up.

The case series of 151 patients reported a 3-year recurrence-free survival probability of 92% for all patients and 87% for the 84 patients with confirmed renal cell carcinoma. The case series of 31 patients reported disease-specific survival of 100%, recurrence-free survival of 89% and overall survival of 63% (all at 80 months).

The specialist advisers listed key efficacy outcomes as radiological confirmation of tumour devascularisation, imaging follow-up to confirm tumour involution at 2 and 5 years, and overall and disease-free survival. They indicated that there is uncertainty about the procedure's efficacy in tumours 4 cm or greater in diameter.

Haemorrhage was reported in 6% (5 of 85) of patients in a case series of 85 patients. Life-threatening haematuria approximately 42 hours after RFA treatment which required transcatheter embolisation was described in a case report.

Haematoma requiring blood transfusion was reported in 1% (1 of 104) of patients in a case series and 1% (1 of 82) of RFA procedures in the non-randomised comparative study of 233 patients. Haematoma not requiring blood transfusion was reported in 5% (4 of 82), including 3 perirenal requiring no treatment and 1 retroperitoneal, of RFA procedures in the non-randomised comparative study of 233 patients. Asymptomatic perirenal haematoma development was reported in 12% (4 of 34; managed conservatively with no sequelae) of RFA procedures in the case series of 31 patients.

Ureteric stricture development was reported after 1% (1 of 120) of treatments and in 1% (1 of 85) and 2% (2 of 104) of patients in case series of 97, 85 and 104 patients respectively.

Urinoma (a collection of fluid resulting from a urine leak) was reported in 1 patient each in the case series of 97 and 85 patients. Ureteropelvic junction obstruction requiring nephrectomy was described in a case report.

Thermal injury to the duodenum requiring laparotomy was reported in 1 patient in the case series of 97 patients.

Renoduodenal fistula was diagnosed 5 days after the procedure in 1 patient in a case report. A CT scan at 6 months showed that the tumour (a clear cell carcinoma) was growing again and an open nephrectomy was performed.

Neuromuscular complications after RFA treatment were reported in 3 of 48 patients in one series. One patient developed persistent laxity of flank muscles. The other 2 developed sensory loss and paraesthesia of the lateral abdominal wall (resolved after 3 months).

The specialist advisers stated that theoretical adverse events include bowel perforation, perirenal haematoma, pelvicalyceal injury, and pain due to intercostal nerve damage.