After a diagnosis of urothelial cancer, doctors will assign a stage to the disease -- determining how deep the tumor has invaded into the bladder and whether there is any spread to the lymph nodes and other sites in the body. Staging is performed to help develop a recommended treatment plan.
The evaluation will include a urogram, which is a type of computed tomography (CT) scan of the abdomen and pelvis. Staging also relies on a procedure called cystoscopy, where a urologist examines the bladder internally, often accompanied by shaving of the bladder tumor in a procedure called transurethral resection of bladder tumor (TURBT).
Cystoscopy, the most sensitive and specific method for identifying bladder cancer, allows the doctor to examine the lining of the bladder and urethra through the use of a cystoscope, a thin camera. Additional evaluation may include a chest x-ray to see if the disease has spread to the lungs.
The most commonly used staging system is the Tumor-Nodes-Metastasis (TNM) classification, which relies on the results of physical examination, biopsy, imaging tests, and surgery, and is considered to be more accurate than clinical staging, which is based only on tests done before surgery. Combinations of the T, N, and M classification are grouped to describe the true stage of disease.
Cancer is also graded as low-grade or high-grade, depending on the appearance of the cells under the microscope, and the grade can also be used to predict the likelihood of recurrence after treatment. This also has implications for the extent of staging studies a patient will need.
When a cystoscopic biopsy reveals a low-grade urothelial tumor, CT scan of the chest is usually not necessary. But if the tumor is high grade, extending its roots into the muscular wall of the urinary bladder, physicians will want to get a CT scan of the chest, which is much more sensitive than an x-ray in ruling out metastases.
If an abnormality is found on staging studies, additional work-up may be pursued. For example, in patients in whom the CT urogram reveals ambiguous enlargement of a single lymph node, a positron emission tomography (PET) scan may be obtained to see whether the enlargement is due to the cancer itself or to inflammation around the cancer.
An emerging area of interest is using magnetic resonance imaging (MRI) of the pelvis for staging urothelial cancer. While the gold standards for staging remain the CT urogram, TURBT, and chest imaging, ongoing studies are evaluating MRI of the pelvis to specifically gauge the tumor's depth of invasion into the bladder wall. A five-point MRI-based scoring system known as VI-RADS (Vesical Imaging Reporting and Data System) has been developed specifically to stage bladder cancer. The main goal of VI-RADS is to overcome the risks and limitations of TURBT (i.e., bladder perforation and under- or over-staging) using noninvasive imaging.
An ongoing trial called BladderPath is assessing whether MRI can substitute for TURBT after a small bladder biopsy has confirmed the presence of bladder cancer, to determine if conservative treatment is possible rather than more radical surgical procedures to complete staging.
Read Part 1 of this series: For Your Patients: Urothelial Cancer 101
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