Salvage Stereotactic Body Radiotherapy for Patients With Prostate Cancer With Isolated Lymph Node Metastasis: A Single-Center Experience

Objective The study objective was to evaluate the efficacy of salvage stereotactic body radiation therapy (SBRT) as a treatment modality in patients with oligometastatic prostate cancer. Methods A total of 16 patients with 18 isolated lymph nodes with recurrent prostate cancer were treated between 2008 and 2013. All patients underwent [11C] choline-positron emission tomography/computed tomography before SBRT. Two patients were treated in different sessions for metachronous metastases. Ten patients received androgen deprivation therapy concomitant to SBRT (total dose range, 12-35 Gy, delivered in 1-5 daily fractions). Results The mean and median follow-up periods were 29.35 and 29.38 months, respectively (range, 6.3-68.8 months). Local disease control and a decrease in serum prostate-specific antigen were obtained in 15 of 16 patients (94%); only 1 patient had an in-field progression. In the 6 patients without androgen deprivation therapy at the time of SBRT, the mean time of deferment of palliative androgen deprivation therapy was 23.7 months (range, 2.5-51 months). At last follow-up, 8 patients had active prostate cancer disease; biochemical progression was observed after a mean time of 7.9 months from the completion of SBRT. One patient died of disease. Overall survival was 94%. The 2-year biochemical relapse-free survival was 44%. Late toxicity (gastrointestinal) was observed in 1 patient who had a G3 toxicity. Conclusions SBRT seems to be safe, effective, and minimally invasive in the eradication of limited nodal recurrence from oligometastatic prostate cancer. SBRT is well tolerated by patients with low toxicity and yielded a local control of the disease.