Safety and Efficacy of CT-Guided Percutaneous Biopsy of Suspicious Subcentimeter Pelvic and Retroperitoneal Lymph Nodes Detected by 11C-Choline PET in Patients With Prostate Cancer.

Background: In patients with prostate cancer, PET using targeted radiotracers can identify increased activity in small morphologically normal lymph nodes, facilitating earlier detection of metastatic disease. Objective: To assess the efficacy and safety of CT-guided biopsy of suspicious pelvic and retroperitoneal lymph nodes measuring <1 cm detected by 11C-choline PET in patients with prostate cancer, with comparison to nodes measuring ≥1 cm. Methods: This retrospective study included patients with prostate cancer who underwent CT-guided percutaneous biopsy of suspicious pelvic or retroperitoneal lymph nodes detected by 11C-choline PET/CT or PET/MRI (performed due to rising or elevated PSA, or known recurrent or metastatic disease) between June 1, 2012 and March 20, 2020. Patient, lymph node, and procedural characteristics, as well as biopsy outcomes and complications, were recorded. Biopsies of lymph nodes measuring <1 cm and of lymph nodes measuring ≥1 cm were compared. Results: A total of 269 patients (mean age 68.7±6.8 years) were included. A total of 156 patients underwent biopsy of lymph nodes measuring <1 cm (range, 3-9 mm); 113 patients underwent biopsy of lymph nodes measuring ≥1 cm (range, 10-35 mm). Lymph nodes <1 cm and lymph nodes ≥1 cm showed no significant difference in diagnostic yield (89.7% vs 92.9%; p=.40). Diagnostic yield was not significantly different between nodes <1 cm and nodes ≥1 cm for any individual anatomic location within the pelvis or retroperitoneum (all p>.05). Malignant yield was lower for nodes <1 cm than for nodes ≥1 cm (44.9% vs 63.7%; p=.003). The single biopsied 3-mm node had a non-diagnostic specimen. Diagnostic yield and malignant yield were 100.0% and 40.0%, respectively, for 4-mm nodes, and 95.5% and 45.5%, respectively, for 5-mm nodes. Patients with nodes <1 cm and nodes ≥1 cm showed no significant difference in minor (12.8% vs 7.1%; p=.16) or major (0.6% vs 2.7%; p=.31) complication rate. Conclusion: The findings support the safety and efficacy of CT-guided biopsy of suspicious subcentimeter pelvic and retroperitoneal lymph nodes detected on 11C-choline PET in patients with prostate cancer. Clinical Impact: Earlier diagnosis of metastatic lymphadenopathy will impact prognostic assessment and management decisions in patients with recurrent prostate cancer.

AJR. American journal of roentgenology. 2022 Dec 07 [Epub ahead of print]

Jamie D Kapplinger, Livia M Frota Lima, Annie T Packard, Mark A Nathan, Jason R Young, Bradley J Stish, David M Hough

Department of Radiology, Mayo Clinic, Rochester, MN., Department of Radiology, Mayo Clinic, Jacksonville, FL., Department of Radiation Oncology, Mayo Clinic, Rochester MN.