This review of the literature aims to summarise what is known in regards to outcomes in patients undergoing cryotherapy in a number of settings: whole gland, salvage and targeted focal therapy. It highlights that more prostate cancers are being diagnosed earlier and so the need for minimally invasive treatments is growing. It also describes how whole gland treatments e.g. radical prostatectomy or radiation, over-treat 30-50% of patients. In 2008 the American Urological Association (AUA) released a consensus that concluded that “cryotherapy is an established treatment option for men with newly diagnosed, or radio-recurrent, organ confined prostate cancer.” Newer generation cryotherapy machines using argon appear to have improved the morbidity from cryotherapy. It has also led to the development of smaller probes. Part of the problem with all meta-analyses is the variation in machines used and also the definition of recurrence and side-effects.
Currently there is no established definition of biochemical failure after cryotherapy but commonly used definitions are ASTRO (three consecutive PSA rises after treatment nadir) and Phoenix (nadir PSA +2). There are very few randomised trials looking at whole gland cryotherapy and none comparing it with active surveillance or surgery. The Cryotherapy Online Database (COLD) registry suggests that in patients who have undergone this treatment the five-year biochemical disease-free survival is 84% in low-risk, 73% in intermediate-risk and 75% in high-risk patients, using the ASTRO criteria, which is comparable to radiation mono therapy. Complication rates have improved with newer machines but the main one is erectile dysfunction (ED) in at least 86% of patients. Fistula rates now seem to be about 1%.
For salvage cryotherapy, the five-year survival rate is roughly 97% and the biochemical failure rate ranges between 44-59%. It is worth bearing in mind however, that many of these patients are also receiving androgen deprivation therapy. A recent retrospective analysis compared salvage cryotherapy with salvage prostatectomy. Salvage prostatectomy had a significantly superior biochemical disease-free survival but there was no difference between disease-specific survival at five years. Side-effects of the two treatments were not compared. Target focal therapy is now being explored and current data suggests a 76% biochemical disease-free survival at three years. Complications appear to be lower e.g. potency rate of 58%. This review suggests that although data on these techniques is growing their long-term ontological outcomes still need to be fully evaluated. To help obtain this data more rapidly, standardisation of machines used and recurrence definitions are required.
