Incidental Diagnosis of Urothelial Bladder Cancer: Associations with Overall Survival

Simple Summary Bladder cancer prognosis is strictly related to the disease stage at diagnosis, suggesting that early detection could lead to improved treatment results. We retrospectively investigated for a possible association between incidental bladder tumor diagnosis and survival. We managed to demonstrate that patients who had been diagnosed incidentally, compared to non-incidentally diagnosed cases, tended to have improved survival, especially if the bladder lesion was first visualized with an ultrasound. However, although we did note marked survival benefit with incidental diagnosis in the subgroup of patients with a muscle-invasive disease, our results show that improved survival in the overall group of patients might have been caused by low-grade cancer overdiagnosis. This study serves as important evidence in the discussion on the possible role of screening for bladder cancer. 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.

Automated summary

Bladder cancer patients diagnosed incidentally tend to have improved survival, especially if the bladder lesion was first visualized with an ultrasound. However, the improved survival might be caused by overdiagnosis of low-grade cancer. This study provides important evidence for the discussion on the role of screening for bladder cancer.