Performance of 68Ga-PSMA PET/CT in Metastatic Prostate Cancers at the Time of Diagnosis and Correlation with Obesity.

Abstract

Objective: The aim of this study was to evaluate the relationship between Galium-68 prostate-specific membrane antigen positron emission tomography combined with computed tomography (⁶⁸Ga-PSMA PET/CT) quantitative parameters and patient obesity, prostate-specific antigen (PSA) levels, and metastasis type in prostate cancer.

Methods: In the present study, we included 112 patients diagnosed with prostate cancer between 2020 and 2024. These patients underwent ⁶⁸8Ga-PSMA PET/CT imaging for staging purposes, with locoregional or distant metastasis detected in the imaging results.

Results: No significant correlation was observed between body mass index (BMI) classification and prostate gland maximum standard uptake values (SUV_max), metabolic tumor volume (MTV), total lesion glycolysis (TLG), standardized uptake value lean (SUL), or SUV_mean values. A weak inverse correlation was found between BMI and PSA levels (p=0.08, r=-0.248), with PSA values decreasing as patient weight increased. The presence of locoregional disease or distant metastasis was not significantly associated with prostate gland SUV_max, MTV, TLG, SUV_mean, or SUL values (p=0.25; 0.667; 0.667; 0.244; 0.126, respectively). However, a significant association was detected between PSA levels and distant metastases or locoregional disease (p=0.02), with higher PSA values observed in patients with distant metastases compared to those with locoregional disease. Additionally, significant correlations were found between the D'Amico risk classification and the prostate gland SUV_max, TLG, SUL, and SUV_mean values (p=0.035, 0.037, 0.012, 0.028, respectively).

Conclusion: PSA levels may assist in estimating whether metastases are local or distant. However, due to the weak inverse correlation between BMI and PSA, it is important that low PSA levels may not necessarily indicate localized disease during clinical evaluation.