Predictive Value of the Log Odds of Negative Lymph Nodes/T Stage as a Novel Prognostic Factor in Bladder Cancer Patients After Radical Cystectomy

Abstract

Background: The effect of lymph node resection on the prognosis of bladder cancer (BLCA) patients receiving radical cystectomy should not be ignored. Our aim was to explore the prognostic value of the log odds of negative lymph nodes/T stage (LONT) and construct a more effective nomogram based on LONT to predict cancer-specific survival (CSS) in postoperative BLCA patients.

Methods: Patients diagnosed with BLCA after radical cystectomy between 2004 and 2015 in the Surveillance, Epidemiology, and End Results (SEER) database were enrolled. We randomly split (7:3) these patients into the primary cohort and internal validation cohort. 86 patients from the First Affiliated Hospital of Nanchang University were collected as the external validation set. Univariate and multivariate cox regression analyses were carried out to seek prognostic factors of postoperative BLCA patients. According to these significantly prognostic factors, a simple-to-use nomogram was established for predicting CSS. Their performances were evaluated by using calibration curves, the concordance index (C-index), the receiver operating characteristic (ROC) curves, and decision curve analysis (DCA). In addition, different risk groups were tested by Kaplan-Meier curves and log-rank tests.

Result: Whether in cancer-specific survival (CSS) or overall survival (OS), LONT was an independent and significant prognostic factor. Through further screening, the ultimate nomogram of CSS was composed of nine independent prognostic factors including LONT, age, race, tumor size, histologic type, T stage, N stage, summary stage and chemotherapy. The C-index of nomogram in the primary cohort, internal and external validation cohort were 0.734, 0.720 and 0.728, respectively. The AUC of predicting CSS at 3 and 5 years were 0.783 and 0.774 in the primary cohort and 0.781 and 0.781 in the validation cohort. The results of calibration and DCA showed good concordance and clinical applicability. Significant differences (P < 0.05) were displayed in CSS among different risk groups.

Conclusion: LONT was regarded as a novel and reliable prognostic factor. Compared with the AJCC staging system, the established nomogram based on LONT can more effectively predict the prognosis of BLCA patients after radical cystectomy.

Keywords: SEER; bladder cancer; log odds of negative lymph nodes/T stage; nomogram; prognosis.

Figure 1

Kaplan-Meier curves of OS (A) and CSS (B) stratified by the LONT stage.

Figure 2

Nomogram for predicting 3-, and 5-year cancer-specific survival rate of bladder cancer patients after radical cystectomy.

Figure 3

Time-dependent ROC curves of the nomogram predicting 3-years (A), and 5-years (C) CSS in the primary cohort. Comparison of the ROC curves between nomogram and other independent factors at the 3-years (B), and 5-years (D) CSS in the primary cohort.

Figure 4

The calibration curves of CSS nomogram at 3- (A), and 5-years (B) in the primary cohort, at 3- (C), and 5-years (D) in the internal validation cohort and at 3 (E), and 5-year (F) in the external validation cohort.

Figure 5

The decision curve analysis (DCA) of CSS nomogram at 3- (A), and 5-years (B) in the primary cohort, at 3- (C), and 5-years (D) in the internal validation cohort and at 3 (E), and 5-year (F) in the external validation cohort.

Figure 6

Kaplan-Meier curves of cancer-specific survival for patients in the low-, intermediate-, and high-risk groups in the primary cohort (A), the internal validation cohort (B) and the external validation cohort (C).