Stereotactic radiotherapy for isolated nodal recurrence of prostate cancer

To report a clinical experience in stereotactic body radiation therapy (SBRT) for isolated nodal metastases from prostate cancer. Between November 2011 and December 2013, 30 patients (39 lesions) were treated with SBRT, delivered using Cyberknife, for recurrent prostate cancer with isolated nodal metastases. Prescribed doses and schedules of fractionation varied, ranging from 24 Gy in 1 fraction to 36 Gy in 3 fractions. Most commonly used schedules were 30 Gy in 3 fractions and 36 in Gy in 3 fractions on alternating days. Biochemical response, acute and late toxicity were analyzed. At a median follow-up of 12 months (range 2-24.9), a significant reduction of PSA was observed in 24 cases, while PSA was stable in 1 case and raised in 9 cases. At the time of analysis, among the 30 patients treated, two were dead for systemic disease; 12 patients experienced a relapse of disease in other sites. Sixteen patients were still free of disease. In 24 cases, imaging evaluation 3 months after treatment was available. No in-field recurrence was detected. SBRT was well tolerated: One patient experienced G2 acute genitourinary toxicity. Late toxicity was evaluated in patients with more than 6 months of follow-up, and only one complained G1 proctitis. We did not observe any acute or late severe toxicity (a parts per thousand yenG3). Our experience shows that SBRT for isolated nodal relapse from prostate cancer is a safe treatment, with promising results in terms of efficacy.