3228 - Outcomes of Stereotactic Body Radiotherapy (SBRT) for Supraclavicular Lymph Node Metastasis (SCLN) among Patients with Metastatic Prostate Cancer

12:45pm - 02:00pm PT

Hall F

Screen: 12

POSTER

Presenter(s)

Andres Frias, MD - Mayo Clinic College of Medicine and Science Rochester, Rochester, MN

A. L. Frias¹, B. J. Stish¹, R. Phillips¹, S. S. Park¹, K. W. Merrell¹, J. M. Wilson¹, M. R. Waddle¹, D. Childs², J. Orme², F. J. Quevedo², G. B. Johnson³, R. J. Karnes⁴, E. D. Kwon⁴, and B. J. Davis¹; ¹Department of Radiation Oncology, Mayo Clinic, Rochester, MN, ²Department of Medical Oncology, Mayo Clinic, Rochester, MN, ³Mayo Clinic, Division of Nuclear Medicine, Rochester, MN, ⁴Department of Urology, Mayo Clinic, Rochester, MN

Purpose/Objective(s): Metastasis directed therapy (MDT) including stereotactic body radiotherapy (SBRT) has demonstrated clinical benefit among select patients (pts) with oligometastatic prostate cancer (PCa). Metastasis to the left SCLNs is a common and early site of distant isolated metastases. Despite evidence supporting the use of radiotherapy to treat pelvic nodal metastases, there are few reports on the use of MDT for SCLN metastases.

Materials/Methods: Sixteen pts with metastatic prostate cancer underwent SBRT/IMRT MDT targeting SCLN metastases. Patient characteristics, treatment information, treatment-related toxicities, and oncologic outcomes were assessed using the Kaplan-Meier method including local recurrence-free survival (LRFS), distant progression-free survival (DPFS), prostate cancer-specific survival (PCSS), and overall survival (OS).

Results: At time of initial PCa diagnosis, patient median age was 58.4 years with a median PSA of 6.7 ng/mL (range: 2.1 – 315). 14 (87.5%) underwent prostatectomy and the remainder primary radiotherapy. The most common Gleason score at diagnosis was 8 - 10 (50%). Thereafter, pts underwent a mean of 2.7 (range: 0-6) additional locoregional treatments prior to SCLN MDT.

At the time of SCLN development, pts had a median age of 67.9 years. 11 (68.8%) pts had castrate resistant disease (mCRPC) at time of SBRT. The mean time from initial diagnosis to development of SCLN metastasis was 10.4 years (range: 4.6 – 19) with median PSA of 2.0 ng/mL (range: <0.1 – 11.2). The median number of SCLN metastatic lymph nodes at time of SBRT was 1 (range: 1-6), six pts (37.5%) had additional sites of disease including nodal (25.0%) or osseous (12.5%) sites. The most common fractionation scheme was 35 Gy in 5 fractions daily (43.8%) with 81.3% of pts receiving concurrent hormonal therapy. 7 pts (43.8%) reported grade 1 treatment-related toxicities including fatigue (n=5) and pain (n=2) with no reported grade = 2 toxicities. Local recurrence occurred in 1 pt at 12.7 months and 5-year LRFS was 90.9%. Distant progression occurred in 10 pts (77.0%) with the most common site being nodal metastases (40%). Mean DPFS was 16.7 months (95% CI: 7.9 – 25.5). Mean PCSS and OS were 4.6 years (95% CI: 3.6 – 5.6) and 4.0 years (95% CI: 2.8 – 5.1), respectively. Pts with castrate sensitive disease had 100% 5-year PCSS, and 58.3% for those with mCRPC.

Conclusion: Among this cohort of men with metastatic PCa who underwent SBRT for SCLN metastases, SBRT was well tolerated with no significant toxicity and demonstrated durable local control in nearly all pts. Despite the prevalence of metastatic progression pts with SCLN metastases demonstrated favorable DPFS and OS. SBRT for SCLN metastases is well-tolerated but the presence of SCLN is usually a harbinger of additional metastatic progression which suggests pts require close monitoring coupled with more intensive systemic approaches.