Incidental Diagnosis of Urothelial Bladder Cancer: Associations with Overall Survival

Abstract

Background: We investigated whether an incidental diagnosis (ID) of bladder cancer (BC) was associated with improved survival.

Methods: We retrospectively reviewed data of consecutive patients with no prior diagnosis of urothelial cancer who underwent a primary transurethral resection of bladder tumor (pTURBT) between January 2013 and February 2021 and were subsequently diagnosed with urothelial BC. The type of diagnosis (incidental or non-incidental) was identified. Overall, relative, recurrence-free, and progression-free survival rates (OS, RS, RFS, and PFS) after pTURBT were evaluated using the Kaplan-Meier curves and long-rank tests. A multivariable Cox regression model for the overall mortality was developed.

Results: A total of 435 patients were enrolled. The median follow-up was 2.7 years. ID cases were more likely to be low-grade (LG) and non-muscle-invasive. ID vs. non-ID was associated with a trend toward an improved 7-year OS (66% vs. 49%, p = 0.092) and a significantly improved 7-year OS, if incidental cases were limited to ultrasound-detected tumors (75% vs. 49%, p = 0.013). ID was associated with improved survival among muscle-invasive BC (MIBC) patients (3-year RS: 97% vs. 23%, p < 0.001), but not among other subgroups stratified according to disease stage or grade. In multivariable analysis, only age, MIBC, and high-grade (HG) cancer demonstrated an association with mortality. PFS and RFS among non-MIBC patients did not differ in regard to the type of diagnosis.

Conclusions: Incidental diagnosis may contribute to an improved survival in BC patients, most probably in the mechanism of the relative downgrading of the disease, including the possible overdiagnosis of LG tumors. Nevertheless, in the subgroup analyses, we noted marked survival benefits in MIBC cases. Further prospective studies are warranted to gain a deeper understanding of the observed associations.

Keywords: bladder cancer; incidental diagnosis; screening; survival.

Figure 1

(A) 7-year overall survival (OS), stratified according to type of diagnosis (incidental vs. non-incidental); (B) 7-year relative survival (RS); (C) 2-year OS; and (D) 2-year RS.

Figure 2

(A) 7-year overall survival (OS), stratified according to type of diagnosis: incidental diagnosis performed with ultrasound vs. non-incidental diagnosis; and (B) 7-year relative survival (RS).

Figure 3

(A) 7-year overall survival (OS) stratified according to cancer grade (low-grade (LG) vs. high-grade (HG)); (B) 7-year relative survival (RS) stratified according to cancer grade; (C) 7-year OS in non-metastatic HG patients stratified according to disease stage (non-muscle-invasive bladder cancer (NMIBC) vs. muscle-invasive-bladder cancer (MIBC)); and (D) 7-year RS according to disease stage.

Figure 4

(A) 7-year overall survival (OS) in high-grade (HG) patients stratified by type of diagnosis (incidental vs. non-incidental); and (B) 7-year RS.

Figure 5

(A) 7-year overall survival (OS) in non-metastatic high-grade (HG) non-muscle-invasive bladder cancer (NMIBC) patients stratified by type of diagnosis (incidental vs. non-incidental); (B) 7-year relative survival (RS); (C) 3-year OS in non-metastatic MIBC patients stratified by type of diagnosis; and (D) 7-year RS.

Figure 6

(A) 3-year recurrence-free survival (RFS) in non-muscle-invasive bladder cancer (NMIBC) patients stratified by type of diagnosis (incidental vs. non-incidental); and (B) 3-year progression-free survival (PFS).