 Introduction/Background The American Cancer Society estimates that in 2023, there will be 82,290 new cases of bladder cancer and 16,710 deaths from the disease in the United States [1]. Bladder cancer has a high tendency toward multifocality at presentation and recurrence after treatment [2]. Urothelial carcinoma (UC) (previously known as transitional cell carcinoma) of the bladder is overwhelmingly the most common histologic type of bladder cancer in industrialized nations, accounting for >90% of all cases [3]. The median age of patients at diagnosis with bladder cancer in the United States is 73 years. Almost 85% of patients with bladder cancer present with hematuria, which is either gross or microscopic and is usually painless and intermittent [4]. UC is a very common tumor, quoted as overall the sixth most common tumor (fourth in male individuals), with the majority of cases arising in the bladder. Primary lesions arising in the upper tract are relatively uncommon at approximately 5% to 10% [1]. The hallmark of UC is multiplicity and recurrence, with nearly 2% to 4% of patients with bladder cancer developing upper tract UC (UTUC). In addition, 40% of patients with UTUC develop UC of the bladder [5]. UTUC has often been grouped with other renal cancers in the literature, making the true incidence of UTUC difficult to evaluate. Pelvicalyceal location is twice as common for UTUC as ureteral location, with estimates suggesting that approximately 15% of renal tumors are actually UC [5]. The incidence of UTUC has been increasing recently, which may be related to overall improved survival of patients with UC of the bladder and the associated risk of developing metachronous UTUC in those patients [5]. UC of the bladder spreads by local extension from the urothelium, through the lamina propria, into the muscularis propria or detrusor muscle layer, then to the perivesical fat.
Pretreatment Staging of Urothelial Cancer.  Introduction/Background The American Cancer Society estimates that in 2023, there will be 82,290 new cases of bladder cancer and 16,710 deaths from the disease in the United States [1]. Bladder cancer has a high tendency toward multifocality at presentation and recurrence after treatment [2]. Urothelial carcinoma (UC) (previously known as transitional cell carcinoma) of the bladder is overwhelmingly the most common histologic type of bladder cancer in industrialized nations, accounting for >90% of all cases [3]. The median age of patients at diagnosis with bladder cancer in the United States is 73 years. Almost 85% of patients with bladder cancer present with hematuria, which is either gross or microscopic and is usually painless and intermittent [4]. UC is a very common tumor, quoted as overall the sixth most common tumor (fourth in male individuals), with the majority of cases arising in the bladder. Primary lesions arising in the upper tract are relatively uncommon at approximately 5% to 10% [1]. The hallmark of UC is multiplicity and recurrence, with nearly 2% to 4% of patients with bladder cancer developing upper tract UC (UTUC). In addition, 40% of patients with UTUC develop UC of the bladder [5]. UTUC has often been grouped with other renal cancers in the literature, making the true incidence of UTUC difficult to evaluate. Pelvicalyceal location is twice as common for UTUC as ureteral location, with estimates suggesting that approximately 15% of renal tumors are actually UC [5]. The incidence of UTUC has been increasing recently, which may be related to overall improved survival of patients with UC of the bladder and the associated risk of developing metachronous UTUC in those patients [5]. UC of the bladder spreads by local extension from the urothelium, through the lamina propria, into the muscularis propria or detrusor muscle layer, then to the perivesical fat.