68Ga-PSMA-I&T PET/CT for assessment of tumor burden in primary lesions of treatmentnaïve prostate cancer

Abstract

To investigate the value of 68Ga-labeled prostate specific membrane antigen (PSMA) PET/CT for assessing tumor load in primary lesions for risk stratification and predicting metastasis of newly diagnosed prostate cancer (PCa). We retrospectively analyzed the data of 36 patients (mean age 71.3 ± 8.6 years, range 56 to 89 years) with newly diagnosed PCa undergoing 68Ga-PSMA-I&T PET/CT from June 2018 to July 2019. SUVmax and SUVmean of the primary lesions were measured, and the primary PSMA tumor volume (PSMA-TV) and total lesion PSMA (TL-PSMA) were automatically measured and calculated in all the patients. The correlations of primary SUVmax, PSMA-TV, and TL-PSMA with PSA and Gleason score (GS) were analyzed, and SUVmax, PSMA-TV and TL-PSMA of the primary lesions were compared among different PCa subgroups. SUVmax, PSMA-TV and TL-PSMA of the primary lesions were all correlated with PSA and GS (P < 0.05). PCa subgroup analysis showed that SUVmax, PSMA-TV and TL-PSMA were all significantly higher in patients with PSA >20 ng/mL than in those with PSA ≤20 ng/mL (P < 0.001), and were higher in patients with a GS ≥8 than in those with a GS ≤7 (P < 0.001). PSMA-TV and TL-PSMA were significantly higher in patients with tumor metastasis than in those without metastasis (P < 0.001), while SUVmax did not differ significantly with tumor metastasis. SUVmax (P=0.002), PSMA-TV (P < 0.001), and TL-PSMA (P < 0.001) were all significantly higher in high-risk group than in low-to moderate-risk group. PSMA-TV and TL-PSMA of 68Ga-PSMA-I&T PET/CT have potential value in predicting risk stratification and metastasis of newly diagnosed PCa.