Objective

The objective of this study was to develop a clinical nomogram to predict gallium-68 prostate-specific membrane antigen positron emission tomography/computed tomography (⁶⁸Ga-PSMA-11-PET/CT) positivity in different clinical settings of PSA failure.

Materials and methods

Seven hundred three (n = 703) prostate cancer (PCa) patients with confirmed PSA failure after radical therapy were enrolled. Patients were stratified according to different clinical settings (first-time biochemical recurrence [BCR]: group 1; BCR after salvage therapy: group 2; biochemical persistence after radical prostatectomy [BCP]: group 3; advanced-stage PCa before second-line systemic therapies: group 4).

First, we assessed ⁶⁸Ga-PSMA-11-PET/CT positivity rate. Second, multivariable logistic regression analyses were used to determine predictors of positive scan. Third, regression-based coefficients were used to develop a nomogram predicting positive ⁶⁸Ga-PSMA-11-PET/CT result and 200 bootstrap resamples were used for internal validation. Fourth, receiver operating characteristic (ROC) analysis was used to identify the most informative nomogram’s derived cutoff. Decision curve analysis (DCA) was implemented to quantify nomogram’s clinical benefit.

Results

⁶⁸Ga-PSMA-11-PET/CT overall positivity rate was 51.2%, while it was 40.3% in group 1, 54% in group 2, 60.5% in group 3, and 86.9% in group 4 (p < 0.001). At multivariable analyses, ISUP grade, PSA, PSA doubling time, and clinical setting were independent predictors of a positive scan (all p ≤ 0.04). A nomogram based on covariates included in the multivariate model demonstrated a bootstrap-corrected accuracy of 82%. The nomogram-derived best cutoff value was 40%. In DCA, the nomogram revealed clinical net benefit of > 10%.

Conclusions

This novel nomogram proved its good accuracy in predicting a positive scan, with values ≥ 40% providing the most informative cutoff in counselling patients to ⁶⁸Ga-PSMA-11-PET/CT. This tool might be important as a guide to clinicians in the best use of PSMA-based PET imaging.

客观的

这项研究的目的是开发一种临床诺模图，以预测在不同的PSA衰竭临床环境中，镓68前列腺特异性膜抗原正电子发射断层扫描/计算机断层扫描（⁶⁸ Ga-PSMA-11-PET / CT）阳性。

材料和方法

 招募了730例（n = 703）根治性治疗后确诊PSA失败的前列腺癌（PCa）患者。根据不同的临床情况对患者进行分层（首次生化复发[BCR]：第1组；抢救治疗后BCR：第2组；根治性前列腺切除术[BCP]后的生化持续性[BCP]：第3组；二线全身用药前的晚期PCa）疗法：第4组）。

首先，我们评估了⁶⁸ Ga-PSMA-11-PET / CT阳性率。其次，使用多变量logistic回归分析来确定阳性扫描的预测因子。第三，使用基于回归的系数来开发诺模图，以预测⁶⁸ Ga-PSMA-11-PET / CT的阳性结果，并使用200个bootstrap重采样进行内部验证。第四，使用接收器工作特性（ROC）分析来识别信息最丰富的列线图得出的截止值。实施决策曲线分析（DCA）来量化诺模图的临床益处。

结果

⁶⁸ Ga-PSMA-11-PET / CT总体阳性率为51.2％，而第1组为40.3％，第2组为54％，第3组为60.5％，第4组为86.9％（p  <0.001）。在多变量分析中，ISUP级，PSA，PSA倍增时间，和临床环境中是一个正扫描（所有的独立预测因子p  ≤0.04）。基于包含在多元模型中的协变量的列线图显示自举校正的准确性为82％。列线图得出的最佳截止值为40％。在DCA中，列线图显示临床净获益> 10％。

结论

这种新颖的列线图证明了其在预测阳性扫描中的良好准确性，其值≥40％提供了在向患者提供⁶⁸ Ga-PSMA-11-PET / CT咨询服务时提供的最多信息。该工具可能对指导临床医生充分利用基于PSMA的PET成像非常重要。