[960] High Intensity Focused Ultrasound (HIFU) in Prostatic Adenocarcinoma – Pathologic Features in Tumor and Non-Tumor Tissue in 45 Treated Cases

P Ryan, L Fahim, A Finelli, N Fleshner, M Robinette, S Radomski, T van der Kwast, A Evans. Mount Sinai Hospital, Toronto, Canada; University Health Network, Toronto, Canada

Background: High Intensity Focused Ultrasound (HIFU) is one of several alternative management options being offered to patients with prostate-confined low risk prostatic adenocarcinoma. Little data exists on the effects of treatment on tumor and non-tumorous prostate tissue. This study summarizes the pathologic features in biopsies of HIFU-treated prostatic adenocarcinoma.
Design: Pretreatment needle biopsies from 45 patients with prostate cancer who received HIFU were identified retrospectively. 30 patients also had post-HIFU biopsy either due to rising PSA interpreted clinically as biochemical failure (n = 22) or as per surgeon practice pattern (n = 8). The Gleason score, location, and extent of tumor were assessed along with (in post-HIFU biopsies) the presence of coagulative necrosis and stromal fibrosis.
Results: Pretreatment Gleason score was 6 or 7 in all cases, with mean tissue involvement of 7.5% and bilateral disease present in 18 cases. 23 patients experienced biochemical failure at a mean follow-up of 13.2 months with one patient commenced on anti-androgen therapy without further biopsy and 22 having repeat needle biopsy - 17 contained adenocarcinoma, 4 had higher Gleason score, 5 had newly diagnosed contralateral carcinoma, and 4 had increased percentage tissue involvement. Of 22 cases without evidence of treatment failure at 12.2 months mean follow-up, 8 had repeat biopsy with 2 containing carcinoma similar to the pre-treatment biopsy. In non-tumor prostate tissue coagulative necrosis was seen in 4 of 30 post-treatment cases (13.3%, mean interval since HIFU 8.5 months), stromal fibrosis in 17 cases (56.7%, 15.3 months), and in 5 cases viable tumour as well as treatment effects were found in the same core.
Conclusions: Notwithstanding that many patients successfully treated on the basis of outside biopsy reports would not be detected in this review the positive biopsy rate is low in cases with stable or undetectable post-HIFU PSA, compared with cases of biochemical failure where >75% have viable tumor on follow-up biopsy. Coagulative necrosis is present in a minority of biopsies and fibrosis may be seen in more than 50% of cases, features whose detection may be influenced by the interval since HIFU. However, in our experience HIFU does not affect ability to apply the modified Gleason scoring system to viable post-treatment tumour.
Category: Genitourinary (including renal tumors)

Monday, March 22, 2010 1:00 PM

Poster Session II # 106, Monday Afternoon

 

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