Review question
How does freezing of the prostate gland (cryotherapy) compare to other treatments in men with prostate cancer who have not been treated before?
Background
Prostate cancer is commonly treated with surgery or radiation if it has not yet spread to other organs. These treatments can have serious side-effects. Freezing of the prostate is another way to treat prostate cancer. This can be done by freezing the whole prostate (whole gland cryotherapy) or only the part of the prostate where the main cancer is (focal cryotherapy). We do not understand well how freezing of the prostate compares to other treatments.
Study characteristics
We searched the medical literature for evidence from trials up to 6 March 2018. We found two randomised trials that compared freezing of the whole prostate to radiation treatment. These included 307 randomised men with prostate cancer (cryotherapy 154 men, radiation 153 men). Their average age was around 70 years. These studies followed men for eight to nine years after treatment. We did not find any studies that compared freezing the prostate to surgery. Also, we did not find randomised trials that compared freezing of parts of the prostate (focal cryotherapy) to radiation, surgery or no treatment.
Key results
We are uncertain of the effects of freezing of the whole prostate compared to radiation treatment on the time to death from prostate cancer, quality of life for urinary, bowel, and sexual function and serious unwanted treatment reactions.
Quality of the evidence
The quality of evidence was very low for all outcomes meaning that the real effect of whole gland cryotherapy may differ a lot from the findings in this review. Further research is very likely to change these findings.
Based on very low quality evidence, primary whole gland cryotherapy has uncertain effects on oncologic outcomes, QoL, and major adverse events compared to external beam radiotherapy. Reasons for downgrading the QoE included serious study limitations, indirectness due to the use of lower doses of radiation in the comparison group than currently recommended, and serious or very serious imprecision.
Traditionally, radical prostatectomy and radiotherapy with or without androgen deprivation therapy have been the main treatment options to attempt to cure men with localised or locally advanced prostate cancer. Cryotherapy is an alternative option for treatment of prostate cancer that involves freezing of the whole prostate (whole gland therapy) or only the cancer (focal therapy), but it is unclear how effective this is in comparison to other treatments.
To assess the effects of cryotherapy (whole gland or focal) compared with other interventions for primary treatment of clinically localised (cT1-T2) or locally-advanced (cT3) non-metastatic prostate cancer.
We updated a previously published Cochrane Review by performing a comprehensive search of multiple databases (CENTRAL, MEDLINE, EMBASE), clinical trial registries (ClinicalTrials.gov, World Health Organization International Clinical Trials Registry Platform) and a grey literature repository (Grey Literature Report) up to 6 March 2018. We also searched the reference lists of other relevant publications and conference proceedings. We applied no language restrictions.
We included randomised or quasi-randomised trials comparing cryotherapy to other interventions for the primary treatment of prostate cancer.
Two independent reviewers screened the literature, extracted data, and assessed risk of bias. We performed statistical analyses using a random-effects model and interpreted them according to the Cochrane Handbook for Systematic Reviews of Interventions. We rated the quality of evidence (QoE) according to the GRADE approach.
We included only one comparison of whole gland cryotherapy versus external beam radiotherapy, which was informed by two trials with a total of 307 randomised participants. The median age of the included studies was around 70 years. The median follow-up of included studies ranged from 100 to 105 months.
Primary outcomes: we are uncertain about the effect of whole gland cryotherapy compared to radiation therapy on time to death from prostate cancer; hazard ratio (HR) of 1.00 (95% confidence interval (CI) 0.11 to 9.45; 2 trials, 293 participants; very low QoE); this would correspond to zero fewer death from prostate cancer per 1000 men (95% CI 85 fewer to 520 more). We are equally uncertain about the effect of quality of life-related urinary function and bowel function (QoL) at 36 months using the UCLA-Prostate Cancer Index score for which higher values (range: 0 to 100) reflect better quality of life using minimal clinically important differences (MCID) of 8 and 7 points, respectively; mean difference (MD) of 4.4 (95% CI −6.5 to 15.3) and 4.0 (95% CI −73.96 to 81.96), respectively (1 trial, 195 participants; very low QoE). We are also uncertain about sexual function-related QoL using a MCID of 8 points; MD of −20.7 (95% CI −36.29 to −5.11; 1 trial, 195 participants; very low QoE). Lastly, we are uncertain of the risk for major adverse events; risk ratio (RR): 0.91 (95% CI 0.47 to 1.78; 2 trials, 293 participants; very low QoE); this corresponds to 10 fewer major adverse events per 1000 men (95% CI 58 fewer to 86 more).
Secondary outcomes: we are very uncertain about the effects of cryotherapy on time to death from any cause (HR 0.99, 95% CI 0.05 to 18.79; 2 trials, 293 participants; very low QoE), and time to biochemical failure (HR 2.15, 95% CI 0.07 to 62.12; 2 trials, 293 participants; very low QoE). Rates of secondary interventions for treatment failure and minor adverse events were either not reported in the trials, or the data could not be used for analyses.
We found no trials that compared whole gland cryotherapy or focal cryotherapy to other treatment forms such as radical surgery, active surveillance, watchful waiting or other forms of radiotherapy.