Development of a Screening Nomogram for Regional Lymph Node Metastasis Development in Muscle Invasive Bladder Cancer after Multiagent Systemic Therapy

PURPOSE/OBJECTIVE(S)

A reliable method of identifying clinically node negative bladder cancer patients at greater risk of developing lymph node metastasis and may require intensified therapy is needed. The purpose of this study was to create a nomogram to quantify the risk for regional lymphatic involvement in non-metastatic muscle invasive bladder cancer.

MATERIALS/METHODS

Usingthe National Cancer Database, patients with clinical T2-4N0M0 urothelial carcinoma of the bladder between the years of 2004 - 2020 were selected. All patients completed multiagent chemotherapy followed by surgery for pathologic nodal staging to determine presence or absence of nodal disease. No neoadjuvant radiation therapy was allowed and patients with history of prior malignancies were excluded. Following a 70:30 training to testing data split, baseline variables were assessed using univariate logistic regression. Variables were selected for inclusion in the multivariate logistic regression model using a combination of previously reported findings in the literature and/or if found to have a p-value < 0.05 on univariate analysis. A nomogram was constructed using this final model with assessment using calibration plots and the area under the receiver operating characteristics curve (AUC), respectively. An empiric cut point was chosen at 95% sensitivity to identify patients at "high" and "low" risk for pathologic nodal disease with overall assessment in both cohorts using chi-square.

RESULTS

A total of 6194patients were identified for study with a median age of 65 years (IQR = 58 - 71 years). Most patients were male (68.0%) with T2 disease (81.2%). The final multivariate model included age at time of diagnosis (OR = 0.99; 95% CI = 0.99 - 1.00; p = 0.172), time from diagnosis to initiation of chemotherapy (OR = 1.00; 95% CI = 1.00 - 1.01; p = 0.005), papillary histology (OR = 0.85; 95% CI = 0.72 - 1.01; p = 0.068), and clinical T stage (Table 1). Model calibration demonstrated excellent goodness-of-fit with good discrimination (AUC = 0.644). Within the training data, high risk patients were seen to have a twofold increase in pathologic nodal disease (N = 835/3924, 21.2%) when compared to those identified as low risk (N = 38/347, 9.9%) (p < 0.001). Validation within the testing data set demonstrated similar results with pathologic node rates of 22.8% and 7.8% for high- and low-risk patients, respectively (AUC = 0.645, p < 0.001).

CONCLUSION

This study demonstrates a clinically applicable risk stratification tool for identifying patients at risk for developing lymphadenopathy in T2-4 bladder cancer and may help guide future research in selecting patients eligible for escalation of therapy. Future studies should aim to externally validate this tool within prospective cohorts, and seek to determine if this nomogram may provide further prognostic utility.

Prognostication of Overall Survival in Muscle Invasive Bladder Cancer: An Application of a Lymph Node Metastasis Nomogram

PURPOSE/OBJECTIVE(S)

The purpose of this study was to determine if a previously developed nomogram predictive of developing pathologic lymph node metastasis after multiagent chemotherapy for clinical node-negative muscle invasive bladder cancer may also prognosticate overall survival (OS) in patients treated with definitive chemoradiotherapy (CRT).

MATERIALS/METHODS

Using the National Cancer Database, we identified all patients with cN0 muscle invasive urothelial carcinoma of the bladder treated with definitive CRT from 2004 to 2020. Patient probability of occult nodal disease was assessed using a previous nomogram developed from those treated with multiagent chemotherapy alone followed by pathologic nodal assessment. Following a 70:30 training and testing data split, variables were assessed for association with OS using the log-rank test, with those with p < 0.05 deemed eligible for inclusion within a multivariate Cox proportional hazards model. Patients were then stratified as high-, medium-, or low-risk for death using the hazard function's prognostic index. The proportional hazards assumption was checked using Schoenfeld residuals and discrimination assessed using dynamic area under the receiver operating characteristics curves (AUC). Validation was assessed within the testing and a retrospectively collected institutional cohort of 15 patients treated from 2014 - 2020 with CRT.

RESULTS

A total of 1047 patients were identified for this study with median age of 78 years (IQR = 70-83 years) and follow-up of 31.3 months (IQR = 16.0 - 56.6 months). Cox analysis revealed patient age (HR = 1.03; 95% CI = 1.02 - 1.04; p < 0.001), Charlson-Deyo Score, and predicted probability of developing future lymphadenopathy (HR = 4.47; 95% CI = 1.83 - 10.93; p = 0.001) were significantly associated with OS. Median OS for those identified as high, medium, and low risk for death on Cox analysis was 34.2 months (IQR = 21.3 - 40.6 months), 38.9 months (IQR = 31.4 - 47.2 months), and 77.8 months (IQR = 56.1 - 100.3 months), respectively (AUC range = 0.615 - 0.870) (p < 0.001). Similar discrimination was seen within the testing cohort as well with significant differences between median OS across each group (AUC range = 0.580 - 0.726) (p < 0.001). Notably, among patients within the institutional cohort, only one patient stratified as high (N = 1/2; 50.0%) or medium risk (N = 0/5; 0.0%) remained alive at time of final follow-up, whereas 88.9% (N = 7/8) of low-risk patients survived (p = 0.051). Similarly, significant differences in OS were again seen between risk groups, with a median OS of 51.3 months and 19.9 months for high- and medium-risk patients, respectively, while median OS for low-risk patients was not reached (p = 0.006).

CONCLUSION

This study demonstrates the prognostic utility of a previously reported nomogram in predictions of OS. Investigation is warranted to explore how radiation and chemotherapy may offset worse OS in those at high risk for occult nodal disease progression.