*4.2. Urine Collection*

Urine samples were obtained from the Urological Research Institute (URI) of San Raffaele Hospital (Milan, Italy). Caucasian patients aged between 32 and 90 years were recruited. The dataset comprised 46 samples: 31 bladder cancer (BC) patients, nine healthy controls, and six with chronic cystitis. BC patients with concomitant or previous prostate, renal, or upper excretory tract cancer; urinary tract infections; or kidney failure were excluded. Urine samples were collected before the surgical intervention and processed soon after. The samples were centrifuged at 300 g for 5 min, aliquoted, and stored at –80 ◦C until use.

## *4.3. UHPLC–High Resolution Mass Spectrometry Analysis*
