背景：前列腺特异性膜抗原（PSMA）PET对于定位前列腺癌患者的原发肿瘤和转移瘤具有高特异性，但很难估计个体的总体生存率。 目的：利用PSMA PET得出的器官特异性总肿瘤体积开发一种预测前列腺癌患者总体生存率的预测风险评分。 材料和方法：回顾性评估2014年1月至2018年12月进行PSMA PET/CT检查的前列腺癌男性患者。所有来自A中心的患者被分为训练（80％）和内部验证（20％）组。从B中心随机选择的患者用于外部验证。通过神经网络自动量化PSMA PET扫描的器官特异性肿瘤体积。使用Akaike信息准则（AIC）指导的多变量Cox回归选择预测风险评分。将定于训练集上的最终预测风险评分应用于两个验证组。 结果：共包括1348名男性患者（平均年龄70岁±8 [标准差]），其中训练组918名患者，内部验证组230名患者，外部验证组200名患者。中位随访时间为55.7个月（IQR，46.7-65.1个月；>4年；429例死亡）。一个体重调整的预测风险评分整合了总体积，骨和内脏肿瘤体积，可以在内部（0.82）和外部（0.74）验证组以及去势抵抗性（0.75）和激素敏感性（0.68）疾病中获得高的C指数值。与仅包含总肿瘤体积的模型相比，预测分数的统计模型适合性得到了改善（AIC，3324 vs 3351;概率比检验，P< .001）。校准图表明模型适合良好。 结论：包括前列腺特异性膜抗原PET得出的器官特异性肿瘤体积的新开发的风险评分对于预测内部和外部验证组的总体生存率具有良好的模型适合性。本文以CC BY 4.0许可证发布。本文还提供了补充材料。此外，本期还发表了Civelek的社论。

Background Prostate-specific membrane antigen (PSMA) PET has high specificity in localizing primary tumors and metastases in patients with prostate cancer, but the individual overall survival probability is still difficult to estimate. Purpose To develop a prognostic risk score using PSMA PET-derived organ-specific total tumor volumes for predicting overall survival in patients with prostate cancer. Materials and Methods Men with prostate cancer who underwent PSMA PET/CT from January 2014 to December 2018 were evaluated retrospectively. All patients from center A were split into training (80%) and internal validation (20%) cohorts. Randomly selected patients from center B were used for external validation. Organ-specific tumor volumes were automatically quantified from PSMA PET scans by a neural network. A prognostic score was selected using multivariable Cox regression guided by the Akaike information criterion (AIC). The final prognostic risk score fitted on the training set was applied to both validation cohorts. Results A total of 1348 men (mean age, 70 years ± 8 [SD]) were included, with 918 patients in the training cohort, 230 in the internal validation cohort, and 200 in the external validation cohort. The median follow-up time was 55.7 months (IQR, 46.7-65.1 months; >4 years; 429 deaths occurred). A body weight-adjusted prognostic risk score integrating total, bone, and visceral tumor volumes obtained high C index values in the internal (0.82) and external (0.74) validation cohorts, as well as in patients with castration-resistant (0.75) and hormone-sensitive (0.68) disease. The fit of the statistical model for the prognostic score was improved compared with a model containing total tumor volume only (AIC, 3324 vs 3351; likelihood ratio test, P < .001). Calibration plots ascertained good model fit. Conclusion The newly developed risk score that included prostate-specific membrane antigen PET-derived organ-specific tumor volumes had good model fit for predicting overall survival in both internal and external validation cohorts. Published under a CC BY 4.0 license. Supplemental material is available for this article. See also the editorial by Civelek in this issue.