Background: Real-world studies have shown that a majority of pts with la/mUC do not receive first-line (1L) systemic therapy (tx), despite guideline recommendations. This cross-sectional study assessed the criteria that Eu5 physicians consider when making decisions about 1L tx for pts with la/mUC. Methods: A quantitative online survey of Eu5 physicians was performed in Aug-Sep 2022. Respondents answered questions related to demographics, practice patterns, and criteria considered in 1L decision-making. Descriptive statistics were used to analyze demographics and responses. Logistic regression was used to analyze physician characteristics associated with reporting no age threshold vs any age threshold when defining platinum ineligibility. Results: 503 physicians (69% oncologists and 31% urologists) completed the quota-based survey. Most respondents had been in practice for >10 years (69%) and treated 5-19 pts with la/mUC per month (58%) in public teaching hospitals (40%), public nonteaching hospitals (24%), and private hospitals (20%). Physicians estimated that they do not prescribe 1L tx for ≈25% of their pts. The majority of physicians selected advanced age (62.0%) and poor performance status (PS; 54.7%) as their top reasons for not prescribing 1L tx, followed by pt refusal (45.9%) and poor renal function (43.1%). Most physicians (78.1%) reported having an age threshold above which they recommend against 1L systemic tx (mean, 74.7 years old [Table]). After adjusting for baseline characteristics, physicians were more likely to have an age threshold if they were from Italy vs Germany (odds ratio [OR] 0.22 [95% CI 0.06-0.73]), practiced in a public nonteaching hospital (OR 0.28 [95% CI 0.10-0.73]) or public/private office settings (OR 0.14 [95% CI 0.03-0.57]) vs private hospital, and if they treated <20 pts/month (2-10 pts: OR 0.36 [95% CI, 0.17-0.74]; 11-19 pts: OR 0.25 [95% CI 0.09-0.62]). Conclusions: 1L systemic tx rates self-reported by Eu5 physicians were higher than those previously published. Many physicians reported having an age threshold for not offering systemic tx, which was relatively low compared with the senior age profile of the la/mUC population. Physicians who reported an explicit age threshold may be inappropriately excluding pts from tx; this could be a driver for systemic tx underutilization in la/mUC.