Incidental diagnosis of bladder cancer in a national observational study in Spain

Introduction: Bladder cancer (BC) is a common malignancy in Spain. The aims of this study were: to identify the proportion of patients diagnosed with BC incidentally or after symptomatic presentation in a contemporary period in Spain; to compare demographic, clinical, and pathologic characteristics between these groups. Methods: This was a retrospective analysis of a multi-centre observational study of 26 hospitals in the Spanish National Health System of all BCs newly diagnosed in 2011. The study represented 21.5% of the Spanish population and hospitals were selected in proportion to Spain's regions to ensure a representative sample. Patients were categorized by whether the cancer was diagnosed incidentally or after symptomatic presentation and baseline demographic, pathologic, and clinical characteristics were analyzed. Results: 2472 were newly diagnosed with BC at the 26 participating Spanish hospitals with 308 (12.5%) of cases diagnosed incidentally and 2164 (87.5%) diagnosed after symptomatic presentation. No differences were observed between patients diagnosed incidentally vs. symptomatically in terms of demographics or measured co-morbidities. Compared to symptomatically diagnosed bladder tumours, those diagnosed incidentally were more likely to have a papillary appearance, to be significantly smaller, and less likely to have positive/suspicious cytology. Additionally, incidentally diagnosed bladder tumours were less likely to be muscle-invasive (11.7% vs. 25.0%, P < .01) nor aggressive at pathology, with 33.6% Grade 3 compared to 50.1%, (P < .01). Conclusions: We identified a significant percentage (12.5%) of new bladder cancer diagnosis made incidentally in a representative sample of the Spanish population. These tumours exhibited less aggressive pathologic characteristics than their symptomatic counterparts.