TRANSCUTANEOUS HIGH-INTENSITY FOCUSED ULTRASOUND AND IRRADIATION - ANORGAN-PRESERVING TREATMENT OF CANCER IN A SOLITARY TESTIS

Objectives: The aim of this study was to determine the feasibility and safety of transcutaneous ablation of human testicular tissue by high- intensity focused ultrasound (HIFU). Methods: Transcutaneous ablation of human testicular tissue by HIFU was performed with equipment previo usly developed for transrectal prostate ablation. This device utilizes a piezoceramic transducer operating at 4.0 MHz with a site-intensity of 1,600-2,000 W/cm(2) To study the histological impact of transcutane ous HIFU, testes of 4 patients with prostate cancer were subjected to transcutaneous HIFU-therapy prior to scrotal orchiectomy in a phase I trial. In a phase II clinical trial, 4 patients with the typical sonog raphic pattern of a tumor in a solitary testis were treated with trans cutaneous HIFU as a minimally invasive organ-preserving approach follo wed by a 6 weeks' course of prophylactic irradiation of the testis wit h 20 Gy. In all 4 patients, the contralateral testis had been previous ly removed for testis cancer. Results: Histologically, HIFU-treated ar eas exhibited signs of cellular necrosis in all cases (n = 4). The bor der between viable and necrotic tissue was extremely sharp comprising only 5-7 cell layers. In the phase II clinical study, we aimed to abla te the entire cancer in a single therapeutic HIFU session. HIFU treatm ent was performed under general anesthesia. As negative side effects w e observed a cutaneous thermolesion in 1 individual. One patient refus ed to undergo postoperative irradiation and developed a local failure. This patient underwent radical orchiectomy. Another patient received two cycles of chemotherapy for a single suspicious retroperitoneal lym ph node diagnosed 6 months after HIFU therapy. Three patients are tumo r-free with a follow-up of 16, 23 and 31 months, respectively. Conclus ions: This study demonstrates the feasibility and safety of transcutan eous testicular tissue ablation by HIFU. Despite the major drawback of this technique, i.e. that no tumor histology is obtained, we believe that transcutaneous HIFU followed by irradiation has the potential to be established as a minimally invasive treatment alternative to organ- preserving surgery for tumors in a solitary testis.