Transitional Cell Cancer: A Comprehensive Guide to Urothelial Carcinoma
Updated: 3 days ago
Medically reviewed by Dr. Baraa Alnahhal, MD · Last reviewed: October 17, 2026
Quick Answer
Transitional cell cancer (urothelial carcinoma) is cancer that starts in the transitional cells lining the urinary tract, with about 90% of cases in the bladder and others in the renal pelvis and ureters. Blood in the urine is typically the first sign [1]. Risk factors include male sex, age 65+, smoking and chemical exposure [1]. Treatment includes surgery, chemotherapy and immunotherapy [1].
What the research says
There is robust evidence that smoking causes bladder and kidney cancer. A systematic review and meta-analysis of 29 published Mendelian randomization studies plus 123 new analyses found that genetic liability to smoking was associated with a higher risk of several cancers, including cancers of the bladder and kidney. (Larsson & Burgess, EBioMedicine, 2022) [2]
Adding immunotherapy around surgery improved outcomes in muscle-invasive bladder cancer. Pooling two phase III trials in cisplatin-eligible patients, event-free survival improved (hazard ratio 0.61, 95% CI 0.48 to 0.78) and so did overall survival (hazard ratio 0.71, 95% CI 0.59 to 0.86), but serious adverse events were more frequent (relative risk 1.32). The authors caution that the two regimens are not interchangeable and that only two trials were available. (Mollica et al., Crit Rev Oncol Hematol, 2026) [3]
Intensifying BCG treatment comes with trade-offs. Across 3 phase III trials with 1,895 patients with high-risk non-muscle-invasive bladder cancer, adding immune checkpoint inhibitors to BCG raised the risk of serious adverse events (relative risk 4.54) and treatment discontinuation (relative risk 2.87) compared with BCG alone, although local urinary side effects were largely similar. (Ciccarese et al., ESMO Open, 2026) [4]
What Is Transitional Cell Cancer?
Transitional cell cancer, medically termed urothelial carcinoma, is a malignancy that begins in the urothelium. This specialized tissue lines the organs of the urinary system, including the bladder, the renal pelvis (the central part of the kidney), and the ureters (the tubes connecting the kidneys to the bladder) [1]. The name "transitional" comes from the unique ability of these cells to stretch as the bladder fills [1] and collapse when it empties.
This condition represents the vast majority of bladder cancer cases in the United States, accounting for approximately 90% of diagnoses [1]. While it is less common in the kidneys — representing only about 7% of kidney cancers [1] — the symptoms and outlook remain similar regardless of the specific location within the urinary tract [1].
What are the symptoms of transitional cell cancer?
Symptoms of urothelial carcinoma may not appear immediately, making awareness of early signs crucial for timely intervention. The most prevalent and often the first indicator is hematuria, or blood in the urine [1]. This may be visible to the naked eye or only detectable through laboratory testing.
In addition to urinary changes, individuals may experience a noticeable lump or mass in the kidney area, specifically between the ribs and hips on the side or back [1]. Persistent fatigue, unexplained weight loss, and chronic low back pain are also common indicators [1]. Some patients report increased frequency or pain during urination [1], which can often be mistaken for a common infection.
What causes transitional cell cancer, and who is at risk?
The cause of transitional cell cancer is unknown, but being male, being older than 65, smoking and long-term exposure to certain industrial chemicals raise the risk [1]. Gender plays a major role; males are four times more likely to develop bladder cancer and twice as likely to develop kidney cancers compared to females [1]. Age is another critical factor, with the majority of diagnoses occurring in individuals over the age of 65 [1].
Environmental and lifestyle factors significantly contribute to the risk profile. Cigarette smoking is a primary risk factor [1] [2], as the body filters tobacco-related toxins through the urinary system. Furthermore, long-term exposure to industrial chemicals — particularly those used in dyes, rubber, leather, textiles, and paint — has been linked to higher incidence rates [1]. Individuals with a history of bladder cancer also face an increased risk of developing similar cancers in the renal pelvis and ureters [1].
How is transitional cell cancer diagnosed and staged?
Healthcare providers utilize a multi-faceted approach to diagnose and stage urothelial carcinoma. Initial screenings typically involve urinalysis to check for blood or cancer cells [1]. Advanced imaging, such as CT scans, MRIs, and ultrasounds, allows providers to visualize tumors [1]. In many cases, a cystoscopy (using a scope to look inside) and a biopsy (tissue sampling) are performed to confirm the diagnosis [1].
Bladder Cancer Staging
Bladder cancer is staged based on how deeply it has invaded the bladder wall.
Renal Pelvis and Ureter Staging
Staging for these areas focuses on the extent of tissue growth, ranging from Stage 0 (abnormal cells confined to the lining) [1] to Stage IV (spread to distant organs or the fatty layer surrounding the kidney [1]).
How is transitional cell cancer treated and managed?
Treatment strategies are tailored based on the cancer's location and stage. For bladder cancer, surgery is common, either to remove the tumor or to perform fulguration (using electricity to burn away cancer cells) [1]. Immunotherapy, specifically the injection of BCG directly into the bladder [1], is a standard approach to help the immune system fight the disease.
For cancers in the renal pelvis and ureters, surgery remains the primary treatment [1]. In advanced cases, chemotherapy, radiation therapy, and targeted therapy (which addresses specific gene mutations) [1] may be employed. Ongoing clinical trials are also exploring the use of heat and lasers to destroy tumors [1] more effectively.
What is the bottom line on transitional cell cancer?
Transitional cell cancer is a serious but often treatable condition, especially when caught in its early stages [1]. Due to its tendency to recur, patients must maintain a consistent follow-up schedule with their healthcare team [1]. By understanding the risk factors and recognizing early symptoms like blood in the urine, individuals can take proactive steps toward effective management and long-term health.
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Frequently Asked Questions
What is the main difference between transitional cell carcinoma and bladder cancer?
Transitional cell carcinoma is a type of cancer, while bladder cancer is a location. About 90% of bladder cancers are transitional cell carcinomas [1].
Is blood in the urine always a sign of cancer?
No, but it is the most common first sign of urothelial carcinoma [1] and should always be evaluated by a doctor.
Can smoking really cause bladder cancer?
Yes. Smoking is one of the most significant risk factors [1] [2] because tobacco-related toxins are filtered by the kidneys and stored in the bladder.
Who is most at risk for this cancer?
Males and people over the age of 65 have a higher statistical risk [1].
What are transitional cells?
Transitional cells are specialized cells in the urinary tract that can stretch and collapse as needed [1].
Is this cancer hereditary?
Specific gene changes are involved in how the cancer develops [1], but most risk comes from environmental and lifestyle factors such as smoking and chemical exposure.
What is BCG treatment?
BCG treatment is a type of immunotherapy where a drug is injected directly into the bladder [1] to stimulate the immune system.
How often does this cancer come back?
Transitional cell cancer has a high recurrence rate [1], which is why long-term monitoring is essential after treatment.
Can chemical exposure from a job cause this?
Yes. Long-term exposure to dyes, rubber, leather, textiles, and paints is a known risk factor [1].
What is a biopsy?
A procedure where a small tissue sample is taken to be examined for cancer cells [1] under a microscope.
What does "muscle-invasive" mean?
The term muscle-invasive means the cancer has grown into the muscle layer of the bladder wall [1], indicating a more advanced stage.
Are there symptoms other than urinary changes?
Yes, including back pain, fatigue, and unexplained weight loss [1].
Is stage IV cancer curable?
Stage IV means the cancer has spread to other parts of the body [1]; treatment focuses on management and improving quality of life.
What is fulguration?
A surgical technique that uses high-energy electricity to burn away cancerous tumors [1].
How is the kidney affected?
The cancer can start in the renal pelvis, the part of the kidney that connects to the ureters [1].
Related Reading
Cytology (Cytopathology): Types, Why It's Done, What Happens and What Results Mean explains how urine cytology checks cells shed into urine for signs of disease.
CT Urogram: What It Is, Why It's Done, How to Prepare and What to Expect explains the contrast CT scan of the urinary system used to look for this condition.
Urine Cytology: Testing Urine for Bladder Cancer Cells explains the urine test that looks for bladder and urinary tract cancer cells.
References
Cleveland Clinic. Urothelial carcinoma (transitional cell cancer). Cleveland Clinic. Accessed October 14, 2026. https://my.clevelandclinic.org/health/diseases/6239-transitional-cell-cancer
Larsson SC, Burgess S. Appraising the causal role of smoking in multiple diseases: a systematic review and meta-analysis of Mendelian randomization studies. EBioMedicine. 2022;82:104154. PMID: 35816897. https://doi.org/10.1016/j.ebiom.2022.104154
Mollica V, Rosellini M, Giannatempo P, et al. Perioperative immune-based treatment for cisplatin-eligible muscle-invasive bladder cancer: a meta-analysis of randomized controlled trials. Crit Rev Oncol Hematol. 2026;228:105648. PMID: 42863770. https://doi.org/10.1016/j.critrevonc.2026.105648
Ciccarese C, Occhipinti D, Troisi P, et al. Safety profile of BCG with or without immunotherapy in non-muscle-invasive bladder cancer (NMIBC): a systematic review and meta-analysis. ESMO Open. 2026;11(10):108529. PMID: 42777327. https://doi.org/10.1016/j.esmoop.2026.108529
Disclaimer: This article is for general educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider for diagnosis and treatment of any medical condition. If you are experiencing a medical emergency, call 911 or your local emergency services immediately.
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