Purpose: As controversy remains regarding the role of metastasis-directed therapy in patients with oligometastatic prostate cancer, we sought to characterize outcomes of metastasis-directed therapy without concomitant androgen deprivation therapy in the specific subset of patients with a solitary metastatic lesion on C-11 choline positron emission tomography imaging whose primary tumor has already been treated.
Materials and methods: We identified 124 consecutive prostate cancer patients from 2008 to 2018 with a solitary oligorecurrent metastatic lesion on positron emission tomography imaging who were treated with metastasis-directed therapy without androgen deprivation therapy from the Mayo Clinic C-11 choline registry. Metastasis-directed therapy consisted of either stereotactic body radiation therapy or surgical excision.
Results: Of these 124 patients, 67 were treated with surgery (median follow-up 54 months) and 57 patients were treated with stereotactic body radiation therapy (median follow-up 53 months). Of patients treated with surgery, 80.5% had >50% decline in prostate specific antigen at first follow-up, and the 3-year radiographic progression-free survival was 29%. Median time to initiation of systemic therapy in this cohort was 18.5 months (interquartile range 8.4-44.7 months). Meanwhile, for patients treated with stereotactic body radiation therapy, 40.3% had >50% decline in prostate specific antigen at first follow-up, and the 3-year radiographic progression-free survival was 17%. Similarly, median time to initiation of systemic therapy was 17.8 months (interquartile range 7.1-42.3 months).
Conclusions: This study represents the first reported series of metastasis-directed therapy without androgen deprivation therapy in patients with solitary oligorecurrent metastatic prostate cancer. These results suggest that metastasis-directed therapy without androgen deprivation therapy can delay initiation of systemic therapy and highlight the need for further prospective study for select patients with solitary metastatic recurrences of prostate cancer.
Keywords: neoplasm metastasis; prostatic neoplasms; radiosurgery.