Comparison of 5 and 6/8 probes technology in prostate cryoablation
Objective: This study describes and assesses the efficacy for increased glandular destruction by using 6-8 cryoprobes in place of the traditional 5 probes. Method In April 1996, a revised method for cryosurgery was begun using 6-8 cryoprobes and by July 1997, 81 men had been treated. This group is compared to our last 82 cases using our 5 probe method. All cases for this study are consecutive. To assure that the groups were similar, comparison was done by entrance PSA, clinical stage, gland volume and Gleason score. Six months following cryosurgery, PSA and residual benign epithelial acini were compared for the two groups.
Results: Prior to cryosurgery, the two groups were comparable for all the above parameters. The degree of overall glandular kill was greater for the 6-8 probe method. Complete glandular ablation for the 5 probe and 6-8 probe methods were 39% and 53% respectively. When one combines none to few residual acini, 67.5% for the 5 probe method and 88.9% for the 6-8 probe, a significant difference (P vol = 0.001). The odds of having none to few remaining acini versus having many residual acini were 3.5 times greater in the 6-8 probe group than for the 5 probe group. No difference was found in rates of tumor persistence or complications.
Conclusions: a revised method for cryosurgery using 6-8 cryoprobes was proven to be more effective for near-grandular ablation than the traditional 5 probe method. It was easily applied, had a wide margin of safety and even shortened our learning time. These innovations have allowed us to more closely approach our goal of complete glandular destruction without added complications.