What Is Urothelial Carcinoma? Causes, Stages & Treatment

Urothelial carcinoma is a cancer that starts in the urothelium, the specialized lining that coats the inside of the urinary tract. It accounts for the vast majority of bladder cancers and can also appear in the kidneys’ drainage system (the renal pelvis), the ureters, and the urethra.¹ Its behavior ranges from slow-growing tumors that stay on the surface to aggressive cancers that invade deep into muscle and spread to distant organs, and the treatment path looks dramatically different depending on which end of that spectrum you’re dealing with.

Where Urothelial Carcinoma Develops

The urothelium lines the entire urinary tract like wallpaper. Starting at the kidney, urine drains into a funnel-shaped space called the renal pelvis, then flows down a narrow tube (the ureter) into the bladder, and finally exits through the urethra. Cancer can form anywhere along this path, though the bladder is by far the most common site. When cancer arises in the renal pelvis or ureter, it’s referred to as upper tract urothelial carcinoma (UTUC), which behaves somewhat differently and is treated with its own set of strategies.

One striking feature of this cancer is its tendency to appear in more than one place at once, or to recur in a different spot after treatment. A tumor removed from the bladder, for instance, can later show up in the ureter. This “field effect” happens because the entire lining has been exposed to the same carcinogens in urine, so cells at multiple sites may undergo cancerous changes independently or nearly so.

What Causes It

Smoking is the single biggest risk factor. Tobacco smoke delivers carcinogens that get filtered through the kidneys and sit in concentrated urine against the bladder wall. The risk isn’t the same for everyone, though. People who carry a genetic variant that slows the body’s ability to break down tobacco chemicals (a slow-acting version of an enzyme called NAT2) face a much steeper increase in risk from smoking than people whose bodies clear those chemicals faster. In one large study, smokers with the slow-acting variant had roughly five times the risk of aggressive urothelial cancer, compared with about one and a half times the risk for smokers with faster-acting versions of the enzyme.² Even secondhand smoke has been investigated as a possible contributor, though the evidence on that front remains unclear.³

Certain occupational exposures also matter. Workers in chemical manufacturing, textile dyeing, and rubber production have historically faced elevated rates of bladder cancer due to long-term contact with aromatic amines, a family of industrial chemicals that includes compounds like benzidine and 2-naphthylamine.⁴ Regulations in many countries have reduced these exposures, but the lag time between exposure and cancer development can be decades, so occupational cases still appear.

A less widely known cause is aristolochic acid, a natural compound found in plants of the Aristolochia family. Some traditional herbal medicines contain this substance, and in certain regions of the world it has been linked to kidney damage and a striking increase in upper tract urothelial carcinoma. Roughly 30 to 45 percent of patients with aristolochic acid-related kidney disease go on to develop upper urinary tract cancer.⁵ In Taiwan, where certain Aristolochia-based remedies were historically prescribed, this is a recognized driver of the disease.⁶ In southeastern Europe, a condition called Balkan Endemic Nephropathy, traced to low-dose aristolochic acid from a weed that contaminates grain fields, causes the same pattern of kidney disease and cancer.

Who Gets It

Urothelial carcinoma is far more common in men than women. In a large U.S. analysis, about three-quarters of cases occurred in men, and females had roughly a third the risk of males overall.⁷ Rates also vary by race and ethnicity. White men carry the highest risk, followed by Black men and Hispanic men. The reasons involve a mix of differences in smoking rates, occupational exposures, and likely some biological factors that remain poorly understood. Age is another major factor: most diagnoses happen after age 55, and the disease grows more common with each decade.

How It Is Diagnosed

The most common first sign is blood in the urine, which may be visible or detectable only on a urine test. Cystoscopy, in which a thin camera is threaded into the bladder, is the standard diagnostic tool and allows doctors to see tumors directly. When a suspicious growth is spotted, it is biopsied or removed during a procedure called transurethral resection of a bladder tumor (TURBT), which serves double duty as both diagnosis and initial treatment.

Urine cytology, which examines shed cells under a microscope, has long been used alongside cystoscopy. The combination achieves very high accuracy, but cytology on its own can miss low-grade tumors.⁸ A growing list of urine-based biomarker tests aims to improve detection without a scope. In the setting of evaluating blood in the urine, these tests have shown sensitivities ranging broadly from about 66 to 100 percent depending on the specific assay, with specificities generally in the 60 to 94 percent range.⁹ None has replaced cystoscopy as the gold standard, but some are being used to space out the frequency of cystoscopies during surveillance. One commercially available genomic urine test, for example, was shown to accurately identify about 78 percent of patients who could safely be monitored with just one cystoscopy per year instead of the usual two or more, cutting the average number of annual procedures by roughly 39 percent.¹⁰

Staging and What It Means for Prognosis

Staging tells you how far the cancer has grown, and in urothelial carcinoma the key dividing line is whether or not the tumor has invaded the muscle wall of the bladder. Tumors that stay in the inner lining or the thin connective tissue just beneath it are called non-muscle-invasive bladder cancer (NMIBC). These make up the majority of new diagnoses and, while they recur frequently, they carry a much better prognosis than tumors that push into or through the muscle.

The TNM system is used to classify the extent of disease. “T” describes how deeply the primary tumor has grown, from Ta (confined to the innermost surface) through T1 (into the connective tissue below the lining) to T2, T3, and T4 (progressively deeper invasion through the muscle wall and into surrounding fat or adjacent organs). “N” captures spread to nearby lymph nodes, and “M” indicates distant metastasis. Higher TNM stages correlate with worse outcomes.¹¹ Grade matters too: low-grade tumors tend to grow slowly and recur without invading deeply, while high-grade tumors are more likely to become muscle-invasive and metastasize.

Treatment for Non-Muscle-Invasive Disease

For tumors that haven’t reached the muscle layer, treatment starts with TURBT to scrape or cut the visible tumor from the bladder wall. For low-risk tumors, a single dose of chemotherapy instilled directly into the bladder immediately after the procedure is the standard follow-up, designed to kill any floating cancer cells before they can reimplant.¹²

For intermediate- and high-risk NMIBC, the go-to treatment after resection is a series of BCG instillations. BCG (Bacillus Calmette-Guérin) is a weakened form of a tuberculosis-related bacterium that, when placed in the bladder, triggers a potent immune response against remaining cancer cells. It reduces both recurrence and the chance of progression to muscle-invasive disease.¹³ BCG was one of the earliest forms of cancer immunotherapy, and it remains one of the most effective for this purpose. A typical course involves weekly instillations for six weeks, sometimes followed by periodic maintenance doses over a year or more. Side effects are mostly local, such as bladder irritation and flu-like symptoms, and usually resolve quickly.

Because NMIBC recurs so often, surveillance is a defining feature of the experience. Patients typically undergo cystoscopies every few months initially, tapering off over years if no recurrence is found. The cumulative burden of repeated procedures is a real quality-of-life issue, which is why better urine-based tests that could safely reduce the frequency of scope exams are a high priority in the field.

Treatment for Muscle-Invasive Bladder Cancer

Once cancer has grown into the bladder’s muscle wall, the stakes change. The standard approach is radical cystectomy — removal of the entire bladder — typically preceded by several cycles of cisplatin-based chemotherapy. In a landmark trial, patients who received chemotherapy before surgery had a median survival of 77 months, compared with 46 months for surgery alone, and were far more likely to have no residual cancer in the removed bladder (38 percent versus 15 percent).¹⁴

After the bladder is removed, urine needs a new exit path. The most common options are an ileal conduit (a piece of intestine fashioned into a tube that drains into an external bag) or a continent diversion such as a neobladder (a pouch made from intestine that connects to the urethra, allowing relatively normal urination). Studies comparing quality of life across diversion types give mixed signals. Some find that patients with continent diversions report better psychological and social well-being.¹⁵ Others, including a large prospective study, found that body image returned to baseline levels faster with an ileal conduit, and that neobladder patients sometimes reported worse urinary function.¹⁶ Still other analyses found no significant difference in quality of life among diversion types after adjusting for age.¹⁷ The choice often comes down to anatomy, the patient’s physical condition, and personal preference.

Not everyone with muscle-invasive disease needs to lose their bladder. Trimodality therapy — an aggressive TURBT followed by a combination of chemotherapy and radiation — has emerged as a bladder-sparing alternative for carefully selected patients.¹⁸ Studies report five-year overall survival rates in the range of 36 to 74 percent and cancer-specific survival of 50 to 82 percent, which overlaps considerably with the outcomes for radical cystectomy.¹⁹ Candidates tend to be patients with a single tumor, no widespread carcinoma in situ, and good bladder function, who are motivated to keep their bladder.

Treatment for Advanced and Metastatic Disease

When urothelial carcinoma has spread beyond the bladder, platinum-based chemotherapy (usually cisplatin or carboplatin with gemcitabine) has been the backbone of first-line treatment for years. For patients whose cancer progresses on or after platinum chemotherapy, immune checkpoint inhibitors have transformed the landscape. These drugs block the interaction between the PD-1 receptor on immune cells and its partner PD-L1 on tumor cells, releasing the brakes on the body’s immune attack. Pembrolizumab is the most established of these, having demonstrated a survival advantage over standard chemotherapy in a randomized trial of previously treated patients.²⁰ It has become a standard of care both in the second-line setting and as a first-line option for patients who cannot tolerate cisplatin.²¹

Enfortumab vedotin, an antibody-drug conjugate, has been another major advance. This drug combines an antibody that homes in on a protein called Nectin-4 (found on most urothelial cancer cells) with a potent chemotherapy payload that gets delivered directly into the tumor cell. In a randomized trial comparing it to standard chemotherapy in patients who had already been treated with both platinum chemo and a checkpoint inhibitor, enfortumab vedotin improved median overall survival from about 9 months to roughly 13 months.²² More recently, enfortumab vedotin combined with pembrolizumab in the first-line setting has shown strong results, and the combination is increasingly being used upfront.

Targeted Therapy Based on Tumor Genetics

A subset of urothelial carcinomas carry specific genetic alterations that can be targeted with precision drugs. The best-developed example involves changes in the FGFR gene family. FGFR3 mutations are among the most common genetic changes in bladder cancer and were recognized early on as a driver of tumor development, particularly in lower-grade, surface-level disease.²³

Erdafitinib, a drug that blocks FGFR signaling, was the first FGFR inhibitor approved for metastatic urothelial carcinoma.²⁴ In a phase 3 trial, patients with FGFR-altered advanced or metastatic urothelial cancer who received erdafitinib lived a median of about 12 months, compared with roughly 8 months for those given standard chemotherapy.²⁵ This means that tumor genomic testing has become an important part of the workup for advanced disease. If a patient’s cancer harbors certain FGFR2 or FGFR3 alterations, erdafitinib offers a meaningful survival benefit that standard chemo does not match.²⁶

Beyond FGFR, researchers classify bladder tumors into molecular subtypes, most broadly luminal and basal. Luminal tumors share gene-expression patterns with the outer layers of normal bladder lining and are enriched for FGFR3 mutations, while basal tumors resemble the deepest cell layer and carry more TP53 and RB1 mutations. Muscle-invasive basal cancers tend to be more aggressive than luminal ones.²⁷ These subtypes can be identified with just a couple of tissue stains, and they may help guide decisions about who benefits most from chemotherapy versus immunotherapy versus targeted agents.²⁸ Routine clinical use of molecular subtyping is still evolving, but the research signals that treatment will become increasingly personalized.

Upper Tract Urothelial Carcinoma

Cancers in the renal pelvis or ureter make up a small fraction of all urothelial carcinomas, but they present unique challenges. The standard surgical treatment is radical nephroureterectomy — removing the entire kidney, ureter, and a cuff of bladder on the affected side. For patients with high-grade upper tract tumors, however, kidney-sparing surgery (removing the tumor endoscopically or through limited resection) is increasingly being studied. A recent comparison found that survival outcomes, including five-year overall survival and three-year recurrence-free survival, were similar between the two approaches for high-grade disease.²⁹ Patients who had kidney-sparing surgery needed more follow-up procedures on average but experienced fewer severe surgical complications and incurred lower overall cost.

Preserving kidney function matters, especially for patients with a solitary kidney, chronic kidney disease, or bilateral tumors. Aristolochic acid-related upper tract cancers are particularly prone to appearing on both sides or recurring in the bladder after surgery, which makes kidney preservation even more consequential for these patients.³⁰

Why Some Tumors Resist Immunotherapy

Despite the success of checkpoint inhibitors like pembrolizumab, a substantial fraction of patients with advanced urothelial carcinoma don’t respond to immunotherapy, and others respond initially but then relapse. Resistance can be present from the start — driven by the tumor’s genetic makeup or an immune environment that suppresses rather than supports an attack — or it can develop during treatment as the cancer adapts.³¹

Some of the specific resistance mechanisms identified in urothelial carcinoma involve mutations that interfere with how immune cells recognize and attack the tumor. For instance, certain genetic changes can dampen the recruitment and activity of T cells and natural killer cells through altered signaling pathways and shifts in the tumor’s metabolic environment. The tumor’s overall mutational burden and the chemical signals it secretes both influence whether immune cells can find and infiltrate it.³² Understanding these pathways is critical for designing combination strategies — pairing checkpoint inhibitors with drugs that target the tumor’s evasion tactics — and several such combinations are in clinical trials now.