Objective: 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).
Methods: 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.
Results: 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.
Conclusion: 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.
目的: 探讨68Ga标记的前列腺特异性膜抗原（PSMA）PET/CT原发灶肿瘤负荷在预测初诊前列腺癌（PCa）危险分层和转移风险中的价值。
方法: 回顾性纳入2018年6月~2019年7月行68Ga-PSMA-I&T PET/CT检查的36例初诊PCa患者，年龄56~89岁，平均年龄71.3±8.6岁。测量出PCa患者原发病灶最大标准化摄取值（SUVmax）和平均标准化摄取值，分析病灶组织对68GaPSMA-I&T的摄取程度。采用三维体积分割技术自动测量出所有PCa患者原发病灶PSMA肿瘤体积（PSMA-TV）并计算出病灶PSMA代谢（TL-PSMA），分析原发灶SUVmax、PSMA-TV、TL-PSMA与血清前列腺特异性抗原(PSA)、Gleason评分(GS)的相关性。所有患者分别根据PSA水平、GS、是否转移和危险程度进行分组，包括PSA≤20 ng/mL组（22例）和PSA>20 ng/mL组（14例），GS≤7组（18例）和GS≥8（18例），非转移组（23例）和转移组（13例）、低-中危组（16例）和高危组（20例），比较不同亚组间PCa的原发病灶SUVmax、PSMA-TV、TL-PSMA之间的差异。用spearman等级相关分析不符合正态分布的定量数据之间的相关性，用Pearson相关系数分析正态分布的定量数据之间的相关性。
结果: PCa原发灶SUVmax、PSMA-TV和TL-PSMA和PSA都有相关性（r分别为0.463，0.550和0.638，P均 < 0.05），SUVmax、PSMA-TV和TL-PSMA和GS都有相关性（r分别为0.467，0.437，0.540，P均 < 0.05）。PCa亚组分析显示：PSA>20 ng/mL组的SUVmax、PSMA-TV和TL-PSMA均显著高于PSA≤20 ng/mL组（z分别为-3.606，-4.035和-4.265，P均 < 0.001）。GS≥8组的SUVmax、PSMA-TV和TL-PSMA均显著高于GS≤7组（z分别为-3.512，-4.145和-3.987，P均 < 0.001）。转移组的PSMA-TV和TL-PSMA均显著高于非转移组（z分别为-2.734，-2.421，P均 < 0.001），而非转移组和转移组SUVmax的差异无统计学意义。高风险组的SUVmax、PSMA-TV和TL-PSMA均高于低-中风险组，差异有统计学意义（z分别为-3.273，-4.155和-4.298，P分别为0.002， < 0.001， < 0.001）。
结论: 68Ga-PSMA-I&T PET/CT肿瘤负荷体积参数PSMA-TV和TL-PSMA在预测初诊PCa危险分层和转移风险中具有一定的潜在优势。
Keywords: 68Ga-PSMA-I&T; metastasis risk; prostate cancer; prostate specific membrane antigen; risk stratification; tumor load.