Development and Validation of a Predictive Model to Evaluate the Risk of Bone Metastasis in Kidney Cancer

Background

Bone is a common target of metastasis in kidney cancer, and accurately predicting the risk of bone metastases (BMs) facilitates risk stratification and precision medicine in kidney cancer.

Methods

Patients diagnosed with kidney cancer were extracted from the Surveillance, Epidemiology, and End Results (SEER) database to comprise the training group from 2010 to 2017, and the validation group was drawn from our academic medical center. Univariate and multivariate logistic regression analyses explored the statistical relationships between the included variables and BM. Statistically significant risk factors were applied to develop a nomogram. Calibration plots, receiver operating characteristic (ROC) curves, probability density functions (PDF), and clinical utility curves (CUC) were used to verify the predictive performance. Kaplan-Meier (KM) curves demonstrated survival differences between two subgroups of kidney cancer with and without BMs. A convenient web calculator was provided for users via “shiny” package.

Results

A total of 43,503 patients were recruited in this study, of which 42,650 were training group cases and 853 validation group cases. The variables included in the nomogram were sex, pathological grade, T-stage, N-stage, sequence number, brain metastases, liver metastasis, pulmonary metastasis, histological type, primary site, and laterality. The calibration plots confirmed good agreement between the prediction model and the actual results. The area under the curve (AUC) values in the training and validation groups were 0.952 (95% CI, 0.950–0.954) and 0.836 (95% CI, 0.809–0.860), respectively. Based on CUC, we recommend a threshold probability of 5% to guide the diagnosis of BMs.

Conclusions

The comprehensive predictive tool consisting of nomogram and web calculator contributes to risk stratification which helped clinicians identify high-risk cases and provide personalized treatment options.

Comparative Diagnostic Performance of Contrast-Enhanced ultrasound versus Baseline Ultrasound for Renal Pelvis Lesions

The aim of this study was to assess the relative efficacy of contrast-enhanced ultrasound (CEUS) and baseline ultrasound (B-US) in diagnosing renal pelvic lesions. B-US findings on 58 suspected renal pelvis lesions were examined. The B-US and CEUS results were classified into five grades. Receiver operating characteristic curve analysis was used to compare the diagnostic efficacy of the two imaging modalities. CEUS characteristics of renal pelvis malignancies at different tumor stages and pathologic grades were examined. In the final diagnosis, 29 patients had malignant lesions (27 transitional cell carcinomas, 1 squamous cell carcinoma and 1 renal cell carcinoma) and 29 had benign lesions. On B-US, echogenicity and renal pelvis separation pattern in patients with malignant renal lesions overlapped those of patients with benign lesions. CEUS significantly increased the diagnostic grade of malignant lesions and decreased the grade of benign lesions (p = 0.000). The area under the receiver operating characteristic curve of CEUS was larger than that of B-US (p = 0.030). Enhancement shape and intensity in the wash-in phase markedly differed in lesions of higher tumor stage and higher pathologic grade, compared with lesions of lower stage and grade. In this study, compared with B-US, CEUS had significantly higher diagnostic efficacy in patients with renal pelvis lesions.