Though fascinating, delving into the history and biology of cryotherapy is not part of this review. Recently, the AUA released its best practice statement on cryosurgery for the treatment of localized prostate cancer [
19]. A cornerstone of this report was the large, retrospective series reported by Cohen with a median follow-up of greater than 12 years. In this report, 370 patients with T1 to T3 prostate cancer treated consecutively from 1991 to 1996 with cryosurgery as primary monotherapy was analyzed. Kaplan-Meier analysis demonstrated a biochemical disease-free survival rate at 10 years of 80.56%, 74.16%, and 45.54% for low, moderate, and high-risk groups, respectively. The 10-year negative biopsy rate was 76.96% [
20]. Another large, retrospective series was reported by Bahn and colleagues. In this report, the charts of 590 consecutive patients who underwent primary cryosurgical ablation for definitive management were reviewed. The mean follow-up of the cohort was 5.4 years. The percentages of patients with low-, medium-, and high-risk prostate cancer were 15.9%, 30.3%, and 53.7%, respectively. Using a PSA-based definition of biochemical failure of 0.5 ng/mL, results were as follows: the 7-year actuarial bDFS for low-, medium-, and high-risk patients were 61%, 68%, and 61%, respectively. The rate of positive biopsy was 13%. Hormonal therapy was given to 91.5% of the subjects before treatment to downsize the gland and consisted of luteinizing hormone-releasing hormone, combined with an antiandrogen agent 3 months to 1 year before cryoablation. Though hormonal therapy was not continued on any patient after cryoablation, it is still difficult to interpret early serum PSA results in this cohort. Lastly it was noted that 4.3% of subjects reported post-operative incontinence, 94.9%of subjects reported post-operative erectile dysfunction and < 0.1% of subjects developed a post-operative fistula. Thus, the rates of morbidity were modest, and no serious complications were observed [
21]. These encouraging results with whole gland treatment have sparked an interest in utilizing this treatment modality for the focal treatment of prostate cancer.
Focal cryoablation was planned to encompass the area of known tumor based on staging biopsies. Forty-eight patients with at least 2-year follow-up had focal cryoablation. Mean follow-up was 4.5 years. Ninety-four percent of the patients treated had stable PSAs according to American Society of Therapeutic Radiology and Oncology (ASTRO) criteria. Of the 24 patients with stable PSAs who were routinely biopsied (n = 24) all were negative. No local recurrences were noted in areas treated. Potency was maintained to the satisfaction of the patient in of 36 of 40 patients who were potent preoperatively. Of the 48, all were continent [
22]. It is the limited morbidity that makes this treatment option quite attractive. These encouraging results have prompted the initiation of two large, multicenter trials assessing the feasibility and efficacy of performing focal cryotherapy in subjects with localized, low-risk prostate cancer.
The use of hormone therapy must be accounted for when interpreting the results from the above studies. In the study by Onik, patients on combined hormone therapy had therapy stopped immediately after treatment in all cases. Nonetheless, the 3-month data should be cautiously interpreted due to potential residual effects of neoadjuvant hormone therapy [
22]. A 2005 study evaluating men with high-risk features for prostate carcinoma, the majority of study participants (67.7%) received neoadjuvant hormones. Despite this, no significant difference was seen in biochemical recurrence-free survival between those who received hormones and those who did not [
23]. Regardless, use of hormones must be taken into consideration when interpreting PSA-recurrence or biopsy results in these patients.