Cryosurgery for Prostate Cancer

Prostate cancer patients have a new therapy alternative — cryosurgery, also called cryoablation or cryotherapy. Urology Centers of Alabama has been offering this treatment for about a year and a half, and the UAB Division of Urology started offering it last month. Cryoablation uses controlled freezing of the prostate gland to destroy cancerous cells. In addition to freezing the cancerous cells, the process also damages connecting tissue and capillaries, limiting the blood supply to the tumor to slow the growth of cancer. It is an option for many patients who are averse to surgical removal of the prostate or who are not good candidates for prostatectomy. “Cryosurgery is just one more option in the treatment of prostate cancer, which is minimally invasive, says Dr. Lee Hammontree with Urology Centers of Alabama. Its use as a salvage treatment for patients for whom radiation has failed is the main reason Dr. Erik Busby, assistant professor with the UAB Division of Urology, Department of Surgery, and his colleague, Dr. Christopher Amling, professor of urology and director of the division, started offering cryosurgery in mid-December. “One of the categories of patients [among] whom it has shown to be better accepted are those who have had recurrences of their disease after radiation at a local level,” Busby says. “This is the patient population we are most interested in applying this to.” Cryosurgery is typically appropriate for patients who also might be good candidates for radiation, who have local disease that has not spread outside the prostate. It is not appropriate for patients with metastatic disease, or patients who have had a prior radical prostatectomy. Busby says he recommends it for patients in the low- to intermediate-risk category and doesn’t feel it is appropriate for patients that have obvious intermediate or high-risk disease. Hammontree, however, says patients with high-grade disease may also benefit, because many are resistant to radiation therapy. Erectile dysfunction is another important consideration in determining which patients are candidates for cryotherapy. “Because it almost invariably causes impotence, candidates would be those that may already be impotent or don’t care about having erections,” Busby says. Hammontree says other side effects he has seen in his practice are irritative voiding and overactive bladder, but those are temporary. The incidence of rectal injury with the newer equipment is very low, he says, less than 1 percent, and he has had no rectal complications in the approximately 100 patients he has treated. A small percentage of patients may develop permanent urinary problems. The procedure is done in the hospital; patients either go home later that day or stay overnight. With the patient under local or general anesthesia, the doctor uses ultrasound guidance to insert six to eight slender cryoprobes through the skin into precise locations within the prostate. A warming catheter protects the urethra from freezing. Thermal sensors track temperatures in and around the prostate to avoid damaging the bladder and rectum and to ensure effective freezing. Liquid argon gas is circulated within the probes, freezing the prostate tissue to minus 40 degrees. Then helium gas replaces the argon to thaw the tissue. The freeze/thaw cycle is usually repeated once more. Patients usually can return to a normal routine within a few days. The dead tissue is re-absorbed or is converted by the body to scar tissue. Cryoablation for prostate cancer has been around since the early 1990s, but until the last few years, only a very small number of urologists offered it. Today, however, cryotherapy is starting to play in increased role in the management of prostate cancer. “It’s been around for years in one form or another,” Hammontree says. “Most recently, technology has led to it being safer and more effective. The equipment we use sort of represents the third generation in terms of cryotechnology.” Earlier versions of the surgery, he said, had a high incidence of injury to surrounding organs, such as the rectum. The newest machines use temperature sensors so physicians can make sure the cancerous areas are treated effectively while ensuring other areas do not freeze. The new generation of cryotherapy also uses argon gas instead of nitrous, which is safer. “Sometimes with the nitrous machines, the ice would continue to progress after you stopped the freezing process,” Hammontree explains. “With the argon machines, you can be more accurate in stopping the ice formation.” In addition to technology improvements, there is now more research data available showing the therapy is effective and safe. However, long-term effectiveness is still under study. As the National Cancer Institute notes in its face sheet on the topic, “The major disadvantage of cryosurgery is the uncertainty surrounding its long-term effectiveness. While cryosurgery may be effective in treating tumors the physician can see by using imaging tests, it can miss microscopic cancer spread. Furthermore, because the effectiveness of the technique is still being assessed, insurance coverage issues may arise.” January 2008