Cryotherapy for localised prostate cancer

Prostate cancer is a common cancer in elderly men and in some will prove fatal. Standard treatments for localised disease include surgery ( radical prostatectomy), radiotherapy and active monitoring. New emerging therapies are being evaluated with the aim of reducing the complication rate associated with standard therapies, as well as developing an effective treatment. One such modality is cryotherapy, a procedure that introduces probes directly into the prostate tumour and kills the malignant cells by a freezing process.

This review aims to evaluate the relative clinical and economic benefits of cryotherapy compared to standard therapies for the primary treatment of localised prostate cancer.

Our search strategy included an electronic search of MEDLINE from 1996 to December 2006, plus EMBASE (Excerpta Medica Database), the Cochrane library, ISI Science Citation Index, Database of Abstracts and Reviews of Effectiveness (DARE), and LILACS to identify all relevant published randomised trials of cryotherapy for localised prostate cancer. Cancerlit and HealthSTAR databases were searched to their final date. Handsearching of relevant journals was undertaken.

Only published randomised trials comparing the effectiveness of cryotherapy with radical prostatectomy, radiotherapy or active monitoring for the primary treatment of men with localised prostate cancer were eligible for inclusion in this review.

Data were extracted from eligible studies, and included study design, participants, interventions and outcomes. Primary outcome measures were biochemical disease-free survival, disease-free survival and treatment-induced complications. Secondary outcomes included disease-specific survival, overall survival, quality-of-life outcome measures and economic impact measures.

There were no randomised trials found comparing cryotherapy with other therapies for the primary treatment of localised prostate cancer. All studies identified were case series. To indicate the level of the available evidence, studies that evaluated cryotherapy as a primary therapy, using transrectal ultrasound guidance and urethral warming in at least 50 patients with localised prostate cancer, and a minimum of one year follow up, were reviewed. Eight case series were identified that complied with these criteria; two were retrospective. The patients recruited (n = 1483) had an age range from 41 to 84 years, stages T1 = 0 to 43%, T2 = 24 to 88%, T3 = 1 to 41%, and T4 = 0 to 14%. The mean preoperative PSA level ranged from 9.7 to 39 ng/mL, with Gleason scores < 7 and ranging from 6 to 37%. One additional study that compared cryotherapy (total cryotherapy and standard cryotherapy with urethral preservation) with radical prostatectomy was also identified and reviewed. In this study the success rates, defined as a post-treatment PSA of 0.2 ng/mL or less, were reported as 96% for total cryotherapy, 49% for standard cryotherapy and 73% for radical prostatectomy. Four studies did not monitor the temperature of the cyro-procedure and reported 17 to 28% of patients had a positive biopsy following cryotherapy with a mean PSA nadir of 0.55 to 1.75 ng/mL (median 0.4 to 1.85 ng/mL). The other four studies used thermocouples to monitor the temperature of the cryo-procedure and reported progression-free survival rates of 71 to 89% with 1.4 to 13% of patients having a positive biopsy post-cryotherapy. At 5 years, overall survival was reported as 89 to 92% in two studies, and disease-specific survival as 94% in one study. The major complications observed in all studies included impotence (47 to 100%), incontinence (1.3 to 19%), and urethral sloughing (3.9 to 85%), with less common complications of fistula (0 to 2%), bladder-neck obstruction (2 to 55%), stricture (2.2 to 17%) and pain (0.4 to 3.1%). Most patients were sent home the following day (range 1 to 4 days).

Cryotherapy offers a potential alternative to standard therapies for the primary treatment of localised prostate cancer. However, the poor quality of the available studies makes it difficult to determine the relative benefits of this modality. Randomised trials are needed to fully evaluate the full potential of cryotherapy in men with this disease. Patients selecting cryotherapy as their therapeutic option should be made fully aware of the reported efficacy, complications and the low-grade evidence from which these data are derived.