A Multi-Institutional Analysis on the Use of Stereotactic Body Radiotherapy (SBRT) for the Treatment of Lymph Node Oligometastases in Prostate Cancer Patients

Abstract

for patients with oligometastatic/oligorecurrent/oligoprogressive lymph node metastases from PCa, metastases-directed therapy is an emerging strategy. The aim of this retrospective study was to evaluate the oncological outcome and pattern of recurrence of patients treated with stereotactic body radiation therapy (SBRT) on lymph node metastases. in this multi-institutional analysis, patients with maximum 5 lymph node metastases from PCa treated with SBRT were included. Primary end-points of the analysis were local control (LC), out-of-field nodal progression-free survival (NPFS), overall progression-free survival (PFS) and overall survival (OS). 109 patients and 155 lymph node metastases were evaluated. Patients’ median age was 70.8 years (range, 51-84) and median PSA before SBRT was 1.88 ng/ml (range, 0.3-45.5 ng/ml). The dose delivered to the target ranged from 25 to 48 Gy in 4-7 fractions; median BED1.5Gy was 198 Gy (range 108.3 – 432 Gy). With a median follow-up of 16 months, LC rates at 1- and 3-years were 93% and 86%, respectively. In-field progression of disease was observed in 11 (7%) lesions. One and 3-years NPFS was 59% and 29% and median NPFS was 15 months. Rates of OS at 1- and 3-years were 100% and 95%. The median time to the administration of a systemic treatment after SBRT was 7.8 months (1.7-54.8). SBRT is an effective and well tolerated treatment option in the management of lymph node metastases from PCa. Prospective trials are necessary to better select patients who benefit the most from this ablative focal treatment, and better define the recurrence patterns.