HIFU dose escalation leads to fewer recurrences in following focal HIFU in prostate cancer
To determine if delivering greater amounts of focused Ultrasound heat energy when treating non-metastatic prostate cancer using focal HIFU leads to lower recurrence rates.
Based on the prospectively maintained HIFU (Sonablate 500) registry cases were identified who underwent a focal HIFU (03/2007 to 12/2016) with standard HIFU delivery or dose-escalated HIFU. In-field treamtent failure was defined by any secondary treatment (ADT/chemotherapy, cryotherapy, EBRT, RRP, or re-HIFU), metastasis from prostate cancer without further treatment, tumour recurrence with Gleason score ≥7 on prostate biopsy, or death from prostate cancer, respectively. 131 cases were treated with two, and 59 cases with three ablative zones respectively and could be used for a matched-pair analysis. Two major criteria were used for mandatory exact matching (baseline Gleason score and mpMRI-defined tumour volume). Other criteria (biopsy maximum cancer core length (MCCL), duration of clinical follow-up, and time to proof of recurrence) were also used and nearest matching accepted. 37 matched pairs were identified. Statistics by R-language.
In the standard HIFU and dose-escalated groups, respectively, PSA (IQR) was 7.18ng/ml (4.6-10.3) and 6.7ng/ml (5.37-8.5), mean prostate volume (range) was 46ml (17-103) and 52ml (19-121), mean tumour volume (range) in both groups were identical at 0.6ml (0.05-2.5). For the two groups, respectively, median biopsy results (IQR) for number of positive cores, MCCL (in cm), and maximal percentage of core were 6 (3-8) vs. 4 (3-5), 6 (4-9) vs. 5 (4-8), and 65 (40-80) vs. 50 (30-67). Gleason score (% of cases) was 3+3=6 in 2/37 (5%), 3+4 in 31/37 (84%), and 4+3 in 4/37 (11%). Median time elapsed until in-field failure was proven (IQR) was 13 month (11.5-24) compared to 11.5 month (9.5-13). Overall, in-field recurrence (%) was found in 11/37 (29.7%) in standard HIFU and 6/37 (16.2%) in dose-escalated HIFU (p=0.002).
Significantly higher rate of in-field treatment failure in focal HIFU using the standard HIFU protocol on the Sonablate 500 compared to a dose-escalation by delivering more energy.