Cryotherapy for the Treatment of Prostate Cancer
Robert Donnell, MD, Associate Professor of Urology
John Schmidt, MD, Clinical Professor of Urology
The clinical departments of the Medical College of Wisconsin endeavor to provide a complete array of treatment choices for all forms of cancer in all age groups. The department of Urology has long offered conventional curative and palliative forms of therapy. Cryotherapy had its beginnings in the 19th century using salt and ice mixtures in contact with breast and cervical cancers. In the 20th century, the availability of liquid nitrogen led to applications for prostate cancer. These early therapies were fraught with complications, because of the inability to control collateral damage to adjacent tissues. In the 1990’s, improvements in the administration and control of cryotherapy brought complication rates down and improved effectiveness. This latter era developed advances such as: ultrasound control of therapy and the extent of freezing; pinpoint thermocouple devices to monitor the health of the sphincter and rectal wall; urethral warming procedures during treatment to prevent slough; multiprobe, percutaneous treatment systems; the substitution of argon gas for cooling and helium for warming; and use of smaller probes to allow computer- generated
individualized brachytherapy – such as treatment templates and computer software to generate isotherm maps based on needle placement.
Cryotherapy offers the advantage of single modality ablative therapy with only a short overnight hospital stay. It offers prostate cancer ablation for patients with newly diagnosed prostate cancer and those who have disease relapse following radiation therapy. Very few options exist for patients who have cancers that recur following radiation therapy. Cryotherapy is a well established salvage therapy for prostate cancer patients who have failed primary radiation therapy. More recently, research has focused on focal or targeted cryotherapy in very select patients.
Treatment outcomes are stratified by pre-treatment risk factors predictive of treatment failure. Patients are segregated into three groups. Low risk patients have PSA<10, T2a or less, and Gleason’s Score =<6. Intermediate risk patients have PSA 10-20, T2b and Gleason’s Score = 7. High risk patients have PSA=> 20, T2c and Gleason’s Score =>7. Treatment effectiveness is measured by early (<25 months) and late (>24 months) biochemical failure rates. The definition of failure is any one of three generally used criterion: Failure of post-treatment PSA to go below 0.8, three
consecutive PSA rises in follow up (Astro), or PSA nadir m+2 (Phoenix). When biochemical failure occurred, it usually met two or more criterion. National statistics suggest patients at low risk for biochemical failure typically have 4 percent early failure and 15 percent late failure. Intermediate risk patients had 25 percent early failure and 15 percent late failure. High risk patients had 25 percent early failure and 25 percent late failure. The current series using modern technology is ongoing. Published rates for five year, disease free survival are: low risk - 65 percent to 92 percent;
intermediate risk - 60 percent to 89 percent; high risk - 48 percent to 91 percent.
Treatment with cryotherapy is not without morbidity. Potential complications include: incontinence, slough of prostatic urethral tissue, urinary retention requiring surgical intervention, and stricture and or bladder neck contracture. The complication rate is on the order of 1 percent to 6
percent with slightly higher rates for patients treated for salvage. Severe complications such as ureteral obstruction, fistula and false passages are rare. Approximately 15 percent of patients treated as primary therapy will have more than one complication, as will 35 percent treated for salvage.
At Froedtert & The Medical College of Wisconsin, cryotherapy offers effective primary or salvage treatment for a subset of our prostate cancer patients. Outcomes are comparable with other treatments and have acceptable attendant morbidity rates. The experience of the Department of Urology with this treatment method has been extensive. Robert Donnell, MD, has one of the largest series in the country. The experience in Milwaukee has recapitulated the national experience with cryotherapy.