Impact of non-regional lymph node metastases accurately revealed on 18 F-PSMA-1007 PET/CT in the clinical management of metastatic hormone-sensitive prostate cancer

Background Non-regional lymph node (NRLN) metastases has shown increasing importance in the prognosis evaluation and clinical management of primary metastatic hormone-sensitive prostate cancer (mHSPC). Hence, this study aimed to investigate the concordance rates between 18 F-PSMA-1007 PET/CT and conventional imaging (CI) in revealing NRLN metastases, and explore the impact of NRLN metastases on the management of primary mHSPC. Methods The medical records of 224 patients with primary mHSPC were retrospectively reviewed, including 101 patients (45.1%) only received CI for TNM classification, 24 patients (10.7%) only received 18 F-PSMA-1007 PET/CT, and 99 patients (44.2%) received both 18 F-PSMA-1007 PET/CT and CI. Among patients who received 18 F-PSMA-1007 PET/CT and CI before initial treatment, the concordance rates between 18 F-PSMA-1007 PET/CT and CI were analyzed. The high-volume disease was defined as the presence of visceral metastases and/or ≥ 4 bone metastases (≥ 1 beyond the vertebral bodies or the pelvis) based on the findings of 18 F-PSMA-1007 PET/CT and/or CI. The primary endpoint was progression-free survival (PFS), and Cox regression analyses were performed to explore independent predictors of PFS. Results A total of 99 patients (44.2%) received both 18 F-PSMA-1007 PET/CT and CI, the concordance rate in revealing NRLN metastases between 18 F-PSMA-1007 PET/CT and CI was only 61.62%, and Cohen’s kappa coefficient was as low as 0.092. Moreover, 18 F-PSMA-1007 PET/CT detected an additional 37 of 94 (39.4%) patients with positive NRLNs who were negative on CI. Cox regression revealed that androgen deprivation therapy (ADT), N1, high-volume, NRLN and visceral metastases were associated with worse PFS (all P < 0.05) in 224 patients. Furthermore, in patients with low-volume disease, the median PFS of patients with NRLN metastases was significantly shorter than that of patients without NRLN metastases (19.5 vs. 27.5 months, P = 0.01), while the difference between patients with low-volume plus NRLN metastases and high-volume disease was not significant (19.5 vs. 16.9 months, P = 0.55). Moreover, early docetaxel chemotherapy significantly prolonged the PFS of these patients compared with ADT alone (20.7 vs. 12.3 months, P = 0.008). Conclusion NRLN metastases could be accurately revealed by 18 F-PSMA-1007 PET/CT, which should be considered a high-volume feature, especially concomitant with bone metastases. Furthermore, patients with low-volume plus NRLN metastases may be suitable for more intensive treatment, such as early docetaxel chemotherapy.