The First Affiliated Hospital of Xi'an Jiaotong University
Introduction: The prognosis of newly diagnosed metastatic hormone-sensitive prostate cancer (mHSPC) has been improved by docetaxel chemotherapy and new hormonal agents, especially for patients with high tumor volume or high risk. However, the discrimination criteria of tumor volume is based on the findings of conventional imaging (CI) according to the number and location of bone or visceral metastases. PSMA PET/CT has higher accuracy than CI to detect metastases, especially non-regional lymph-node metastases (M1a). Herein, this study will investigate the role of PSMA PET/CT on the assessment of tumor volume and the effects of early chemotherapy on the outcome of these patients. Methods: The medical records of 224 patients with newly diagnosed mHSPC who received CI and/or PSMA PET/CT before treatment were retrospectively reviewed. The concordance rate of PSMA PET/CT with CI for the identification of T, N, M1a, M1b, M1c and tumor volume disease was compared. The primary endpoint was progression-free survival (PFS) and the prognostic value of PSMA PET/CT was explored by Kaplan-Meier survival analysis. Results: 99 patients (44.2%) received both CI and PSMA PET/CT before treatment. Among them, the rate of concordance between PSMA PET/CT and CI were 89.90%, 84.85%, 82.83%, 86.87% and 90.91% for T, N, M1b, M1c and tumor volume diseases, respectively. However, the rate of concordance between PSMA PET/CT and CI was only 61.62% in patients with M1a, because PSMA PET/CT could detect more non-regional lymph-node metastases. Moreover, Kaplan-Meier analyses showed that patients with M1a had worse PFS than those without M1a (16.7 months vs. 22.0 months, P=0.001). For patients with low tumor volume, subgroup analysis showed that the PFS was significantly worse for patients with M1a than those without M1a (19.5 months vs. 27.4 months, P=0.001), which was similar to patients with high tumor volume (19.5 months vs. 16.9 months, P=0.55). Furthermore, compared to androgen deprivation therapy (ADT) alone, ADT combined with docetaxel chemotherapy could significantly prolong PFS for patients with low tumor volume and M1a (12.3 months vs. 20.7 months, P=0.008). Conclusions: PSMA PET/CT severs as a valuable tool to detect more stage M1a mHSPC. Furthermore, in patients with low tumor volume, the presence M1a is a poor prognostic characterstics, and may benefit more from ADT combined with docetaxel chemotherapy. SOURCE OF Funding: None
