Introduction and Technique

Renal Cryotherapy Overview

In the year 2007, there were an estimated 51,190 new cases and 12,890 deaths from kidney cancer 1. Historically, a large percentage of new renal cancer cases was discovered with metastases; however, contemporary series show increased rates of the detection of small (<4cm) renal tumors primarily well before any apparent clinical signs or symptoms as a result of diagnostic testing (including the use of advanced cross-sectional imaging) for other conditions2,8. Traditionally, radical nephrectomy surgery has controlled renal cancer3, but as the transition to the early diagnosis of incidentally discovered small renal masses occurred, surgical treatment of renal masses also evolved. Nephron-sparing surgery, initially developed for patients with solitary kidneys or compromised renal function, emerged as the treatment of choice for renal masses smaller than 4 cm, even in patients with normal contralateral kidneys. Long term cancer control and renal function after partial nephrectomy has been equal to the results of radical nephrectomy4,5. Numerous nephron-sparing options now exist, including open partial nephrectomy, laparoscopic partial nephrectomy6, and minimally-invasive percutaneous techniques for tissue ablation such as cryotherapy.

Techniques for Nonpercutaneous Renal Cryoablation

Exposure for renal cryoablation may be obtained open and laparoscopically. Initially cryosurgery via an open approach was described for patients with single renal units7. As described, the technique requires a flank incision large enough for kidney mobilization and tumor exposure; ultrasound is used to identify tumor location and to guide and verify cryoprobe placement. One large open renal cryoablation series included 29 patients with localized renal tumors8. In this study, the selected open approach (subcostal incision, transperineal mobilization) maximizes mobilization and exposure of the kidney and facilitates ultrasound monitoring. Seventeen cases were on protocol for cryoablation of masses of 4 cm or less (avg. 2.2 cm); twelve more were treated off-protocol but included in the report, either having already undergone cryoablation treatment, or not meeting inclusion criteria. Using a thermosensor at the tumor margin, a double-freeze sequence was performed using a liquid nitrogen-based unit to cool each cryoprobe to -140°C to -180°C until margin temperatures were verified at -40°C. The average hospital stay was 3.4 days. At a median intermediate follow-up of 16 months, all patients except one were radiologically tumor free. The single patient who was found to have a solid renal lesion that was unchanged in size at the 3-month postoperative MRI was determined to have a microscopic focus of renal cell carcinoma. After 12 months of observation, the patient elected a repeat open cryosurgical procedure with subsequent complete radiographic resolution of the cancer. The open approach allows a renal-sparing treatment with excellent sonographic monitoring.

The laparascopic approach offers the renal sparing benefits of open exposure, but with less morbidity. The kidney is generally approached transperitoneally for anterior and anterolateral tumors, or retroperitoneally for posterior and lateral tumors. After kidney mobilization and adequate tumor exposure, cryoprobes are placed into the tumor through the laparoscopic trocars or transcutaneously; placement is monitored visually and via laparoscopic ultrasound probes. One study of 32 patients (maximum tumor size of 4 cm) reported average hospital stay of 1.8 days and median two week time to full recovery. Following the double-freeze laparoscopic cryoablation, 20 patients had follow-up MRI at one year; five had no incidence of disease, and 15 had lesions that decreased in size by an average of 66%. Overall, the average study follow-up was 16 months (range 7-23) with no recurrence. Twenty-three patients underwent post-procedure biopsies of the small residual mass, which were all negative. Two other noteworthy studies describe monitoring of probe placement with an end firing ultrasound in three patients9, and sonographic guidance during laparascopic renal cryoablation of 26 tumors in 25 patients10.

Tissue cracking is a small concern, but it is important to note that fewer incidents of this are observed when an array of smaller gauge cryoprobes are used rather than a single larger (>3.2mm) probe, and there is little to no movement of the cryoprobe during the thaw cycle.11

Studies that report follow-up results affirm the promise of laparoscopic renal cryoablation. In one published report, three-year cancer specific survival in 51 patients undergoing cryotherapy for a unilateral, sporadic renal tumor was 98%. Renal function was not compromised and surgical complications were minimal12.

Footnotes
  1. American Cancer Society. Cancer Facts & Figures 2007. Atlanta: American Cancer Society; 2007.
  2. Hollingworth JM, Miller DC, Daignault S, Hollenbeck BK. Rising incidence of small renal masses: a need to reassess treatment effect. J Natl Cancer Inst (2006) 98;18:1331-1334.
  3. Robson CJ, Churchill BM, Anderson W. The results of radical nephrectomy for renal cell carcinoma. J Urol 1969; 101:297-301.
  4. Uzzo RG, Novick AC. Nephron sparing surgery for renal tumors: indications, techniques and outcomes. J Urol 2001; 166:6-18.
  5. Fergany AF, Hafex KS, Novick AC. Long-term results of nephron sparing surgery for localized renal cell carcinoma: 10-year follow-up. J Urol 2000; 163:442-445.
  6. Janetschek G, Daffnet P, Pexchel R. Bartsch G. Laparoscopic nephron sparing surgery for small renal cell carcinoma. J Urol 1998; 155:1152-1155.

  7. Delworth MG, Pisters LL, Fomage BD, von Eschenback AC. Cryotherapy for renal cell carcinoma and angiomyolipoma. J Urol 1996; 155:252-255.
  8. Rukstalis DB, Khorsandi M, Garcia FU, et al. Clinical experience with open renal cryoablation. J Urol 2001; 56:748-753.
  9. Feld RI, McGinnis DE, Needlement L, et al. A novel application for the end-first sonographic probe: guidance during cryoablation of renal masses. Am J Roentgenol 1999; 173:652-654.
  10. Remer EM, Hale JC, O'Malley CM, et al. Sonographic guidance of laparoscopic renal cryoablation. Am J Roentgenol 2000; 174:1593-1596.
  11. Wyler S, Sulser T et al. Intermediate-term results of retroperineoscopy-assisted cryotherapy for small renal tumors using multiple ultrathin cryoprobes. European Urology 51; 4:971-979.
  12. Gill IS, Remer EM, Hasan WA et al. Renal cryoablation: outcome at 3 years. J Urol (2005) 173; 1903-1907.