According to results recently published in the journal Cancer, cryosurgery may be an effective treatment option for patients with high-risk, early prostate cancer who are unwilling to undergo surgery or radiation therapy.

Prostate cancer is the second most commonly diagnosed cancer in men in the United States. The prostate is a walnut sized gland that is located between the bladder and rectum. It is responsible for the formation of a liquid that is a component of semen. Early prostate cancer refers to cancer that has not spread from the prostate. Standard treatment options for early prostate cancer include the surgical removal of the prostate (prostatectomy) and/or radiation therapy to the area of the prostate or conservative management which includes no treatment until the progression of cancer. Some patients are unwilling to undergo a prostatectomy or radiation therapy due to associated side effects; however, they are at a high risk of developing a cancer recurrence. Researchers have been evaluating novel ways in which to effectively treat prostate cancer with a reduction in side effects associated with therapy.

Even though a patient may have early-stage prostate cancer, they are further categorized into those who are at a high-risk, intermediate-risk or low-risk of developing a cancer recurrence. Patients at higher risks of developing a recurrence are often encouraged to undergo more aggressive therapy than those with low-risk prostate cancer. Patients with early prostate cancer are often stratified into their risk groups through their prostate specific antigen (PSA) levels, and their Gleason score. Prostate specific antigens are proteins that are normally shed by the prostate and can be detected in circulating blood. Higher PSA levels may indicate the presence of prostate cancer, as well as progression of prostate cancer, response to therapy in patients with prostate cancer, or the risk of a recurrence. Gleason score refers to the aggressiveness of the cancer, and is determined through laboratory analysis. Patients with higher PSA levels and higher Gleason scores are considered to be high-risk, and those with low PSA levels and Gleason scores are considered to be low-risk for cancer progression or recurrence.

What is Cryosurgery?

Cryosurgery is a new treatment procedure that is still in investigative stages for prostate cancer. Cryosurgery is a technique that kills cancer cells by freezing them with sub-zero temperatures. During this procedure, hollow steel probes, guided by ultrasound, are placed inside and surrounding the cancer. Liquid nitrogen is then circulated through the probes, freezing the cancer cells and creating a ball of ice that surrounds the cancer. Once an adequate ice ball is formed, heated nitrogen is circulated through the probes. This process is then repeated. A heated probe is placed near the urethra throughout the freezing process so that the urethra is protected during the entire procedure. It is believed that cryosurgery creates cancer- killing effects through 3 distinct processes. First, ice crystals formed within cells are known to be lethal to nearly all cells. Second, when the ice forms around the cell, it draws water out of the cell which collapses many of the walls or membranes within the cell. Third, when the ice surrounding the cells melts through the heating process, the water rushes back into the shrunken cell and causes it to burst.

Researchers from the Columbia Presbyterian Medical Center recently reviewed data to evaluate cryosurgery in the treatment of men with early prostate cancer. Cryosurgery involves the placement of probes that reach freezing temperatures through the skin into the prostate under image guiding, such as ultrasound. The area of the prostate that contains the cancer then undergoes a few cycles of freezing and thawing. Cryosurgery is still being evaluated in clinical trials to determine its effectiveness in the treatment of various cancers such as prostate cancer. The data included 65 men who had early, high-risk prostate cancer and had not received prior therapy and underwent cryosurgery between 1998 and 2002. At nearly 3 years following treatment, all patients were still alive, and nearly 82% of patients are expected to survive 6 years. In addition, PSA levels had remained stable in over 83% of patients. Two patients (3.1%) experienced rectal pain and incontinence from the procedure.

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The researchers concluded that according to this data, cryosurgery appears to be an effective treatment option in patients with early, high-risk prostate cancer. Longer follow-up and direct comparison with other treatment modalities is necessary to truly define the clinical role of cryosurgery in this patient population. Patients with early, high-risk prostate cancer who do not with to undergo a prostatectomy or radiation therapy may wish to speak with their physician regarding the risks and benefits of cryosurgery or the participation in a clinical trial further evaluating cryosurgery or other therapeutic approaches. 

Cryosurgery for locally recurrent prostate cancer

Researchers from Canada conducted a clinical trial evaluating cryosurgery in 118 patients with prostate cancer who had a local recurrence of their cancer following radiation therapy. Approximately 1.5 years following cryosurgery, 87% of patients were free of cancer according to biopsy results, and 68% of patients had a PSA level of 4 or less. Variables attributing to an unfavorable outcome following cryosurgery included a Gleason score (aggressiveness of cancer) of 8 or greater prior to radiation and cancer that extended outside of the prostate upon diagnosis. Approximately 10% of patients experienced complications from the surgery, including rectourethral fistulas (a passage between the rectum and urethra) and severe incontinence.

These results indicate that cryosurgery may be an effective local treatment option for patients who have failed prior radiation therapy. However, patients that receive optimal benefit from this therapy must have localized, early stage prostate cancer and a low Gleason score. Patients with localized, recurrent prostate cancer may wish to speak with their physician about the risks and benefits of participation in a clinical trial further evaluating cryosurgery or other treatment options. 

References: 

  1. Prepelica K, Okeke Z, Murphy A, et al. Cryosurgical ablation of the prostate: High-risk patient outcomes. Cancer. 2005; 103: 1625-1630.
  2. Journal of Urology, Vol 165, No 6, pp 1937-1942, 2001

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