Transitional Cell Carcinoma of Renal Pelvis
Transitional cell carcinoma (also called urothelial carcinoma) of the renal pelvis is a cancer that arises from the specialized cells lining the collecting system of the kidney, where urine is collected before flowing into the ureter. Along with similar cancers of the ureter, it is classified as upper tract urothelial carcinoma. It is much less common than urothelial cancer of the bladder but shares many similar features and risk factors, including smoking, exposure to certain chemicals, and, in some patients, inherited conditions such as Lynch syndrome. Common presenting features include blood in the urine, flank pain, and, in some cases, symptoms of obstruction. Evaluation combines imaging (particularly CT urography), urine studies, and, when needed, direct visualization with ureteroscopy and biopsy.
What is it?
The renal pelvis is a funnel-shaped structure inside the kidney that collects urine from the smaller calyces and channels it into the ureter, the tube that carries urine down to the bladder. Like the ureter and bladder, the renal pelvis is lined by a specialized type of cell called urothelium (also historically called transitional epithelium). Cancers that arise from these cells are called urothelial carcinomas or, in older terminology, transitional cell carcinomas. When they occur in the renal pelvis or ureter, they are collectively referred to as upper tract urothelial carcinoma (UTUC). Upper tract urothelial carcinoma is much less common than urothelial cancer of the bladder but shares many similar features and risk factors.
Transitional cell (urothelial) carcinoma is the most common type of cancer arising within the renal pelvis, distinct from renal cell carcinoma (which arises from the kidney’s filtering tissue and is much more common overall as a “kidney cancer”). Less common types of cancer that can occur in the renal pelvis include squamous cell carcinoma (often associated with chronic irritation, such as from long-standing stones or infection) and adenocarcinoma (rare).
Risk factors for upper tract urothelial carcinoma are similar to those for bladder urothelial carcinoma. Smoking is the most important modifiable risk factor and significantly increases the risk. Occupational exposures to certain chemicals (such as aromatic amines used historically in the dye, rubber, and chemical industries) also increase the risk. A history of bladder cancer is a strong risk factor for developing upper tract urothelial carcinoma, and the two conditions are frequently associated. Chronic urinary tract infections, kidney stones, and other conditions causing long-standing irritation may contribute in some cases. Certain medications, including long-term high-dose use of certain analgesics (particularly phenacetin, which is no longer commonly available), have been associated with increased risk. Aristolochic acid, found in certain herbal preparations and previously implicated in Balkan endemic nephropathy, is a well-established cause. Male sex, older age, and certain hereditary conditions—particularly Lynch syndrome (also called hereditary nonpolyposis colorectal cancer, HNPCC)—also increase risk. Lynch syndrome is an important consideration because it predisposes to upper tract urothelial carcinoma along with colorectal, endometrial, and other cancers, and identifying it has important implications for the patient and family.
Symptoms of upper tract urothelial carcinoma depend on the tumor’s location, size, and stage. The most common presenting symptom is blood in the urine, which may be visible (gross hematuria) or detected only on urine testing (microscopic hematuria). Flank or back pain is another common symptom, often related to obstruction of urine flow or, less commonly, to the passage of blood clots through the ureter. Some patients present with symptoms of urinary obstruction, such as those associated with hydronephrosis (swelling of the kidney’s collecting system due to obstructed urine flow). Less commonly, patients may present with weight loss, fatigue, or other symptoms suggestive of advanced disease. In some cases, the tumor is identified incidentally on imaging done for other reasons.
The diagnostic evaluation of suspected upper tract urothelial carcinoma typically involves several components.
Imaging is central to the evaluation. CT urography—a dedicated CT protocol that includes non-contrast, contrast-enhanced, and delayed (excretory phase) images to visualize the collecting system as it fills with contrast-excreted urine—is the primary imaging test. It provides detailed visualization of the renal pelvis, calyces, ureter, and bladder, and can identify filling defects, wall thickening, and other features suggestive of tumor. MR urography is an alternative when CT is contraindicated (such as in patients with iodinated contrast allergy or, in some cases, kidney function limitations), though it has some limitations compared with CT urography. Retrograde pyelography (in which contrast is injected up the ureter during cystoscopy) may be used in specific circumstances.
Urine studies are also important. Urine cytology (microscopic examination of cells shed into the urine) can identify high-grade urothelial cancers with reasonable sensitivity, though it is less reliable for low-grade tumors. Newer urine-based molecular tests are being incorporated into practice in selected settings.
Cystoscopy (visual examination of the bladder with a small scope) is performed to evaluate for concurrent bladder tumors, which are common in patients with upper tract disease. Ureteroscopy (visual examination of the ureter and renal pelvis with a very thin scope passed up from the bladder) allows direct visualization of upper tract lesions and biopsy for tissue diagnosis. Ureteroscopy is increasingly important in modern practice because it can help distinguish between low-grade and high-grade tumors and guide treatment decisions, particularly when kidney-sparing approaches are being considered.
Staging of upper tract urothelial carcinoma includes CT of the chest, abdomen, and pelvis to evaluate for distant spread (metastasis), as well as consideration of bone or brain imaging in specific circumstances. Blood tests including kidney function (creatinine and eGFR) are important because they influence treatment options, particularly the ability to receive chemotherapy that includes cisplatin.
In selected patients, particularly those with young age at diagnosis, multiple tumors, family history of related cancers, or other features suggestive of a hereditary syndrome, evaluation for Lynch syndrome may be appropriate. This can involve tumor testing (for microsatellite instability or mismatch repair deficiency) and, when appropriate, genetic counseling and germline genetic testing.
Important to Know
Management of transitional cell (urothelial) carcinoma of the renal pelvis is highly individualized based on the tumor’s stage, grade, location, size, patient’s kidney function, overall health, and preferences. Care is best delivered by multidisciplinary teams that include urologists (particularly urologic oncologists), medical oncologists, radiation oncologists (in selected cases), radiologists, pathologists, geneticists, and other specialists as needed.
Treatment is generally categorized based on risk stratification. Low-risk disease—typically low-grade, small (usually less than 2 cm), unifocal (single) tumors without invasion into deeper tissues—may be considered for kidney-sparing approaches when appropriate. High-risk disease—including high-grade tumors, larger tumors, multiple tumors, tumors with invasion, or tumors with concerning features—generally requires more aggressive treatment, most often radical nephroureterectomy.
Radical nephroureterectomy is the standard treatment for most high-risk upper tract urothelial carcinoma. This procedure involves removal of the entire affected kidney, the entire ureter, and a small cuff of the bladder around the ureteral opening (since urothelial cancer can occur in that area). It may be performed using open, laparoscopic, or robotic-assisted techniques. Lymph node dissection is often included, particularly for higher-risk tumors, and helps with staging and, in some cases, treatment.
Kidney-sparing approaches (also called nephron-sparing management) may be appropriate in selected patients with low-risk disease or in patients who need to preserve kidney function (such as those with a solitary kidney, bilateral disease, or chronic kidney disease). Options include endoscopic treatment via ureteroscopy (with laser ablation of the tumor and follow-up ureteroscopies to monitor for recurrence), percutaneous approaches, or segmental ureterectomy (removal of the affected segment of the ureter with reconstruction) for distal ureteral tumors. Recently, intraluminal instillation of chemotherapy (such as mitomycin) delivered through a catheter into the upper tract has been used in selected patients with low-grade upper tract disease as a kidney-sparing option.
Chemotherapy plays an important role in many cases. Neoadjuvant chemotherapy (chemotherapy given before surgery) is increasingly used in patients with high-risk disease and adequate kidney function, and can improve survival. Adjuvant chemotherapy (given after surgery) may also be considered based on final pathology findings, particularly for patients who did not receive neoadjuvant treatment. Standard chemotherapy for urothelial cancer is generally cisplatin-based, which requires adequate kidney function; alternative regimens are available for patients who cannot receive cisplatin.
For advanced or metastatic disease, systemic therapy is central. Options include cisplatin-based chemotherapy, immune checkpoint inhibitors (immunotherapy), targeted therapies (such as FGFR inhibitors in tumors with specific alterations, and antibody-drug conjugates such as enfortumab vedotin), and, in specific circumstances, radiation therapy for symptom management. Clinical trials play an important role for many patients with advanced disease.
Bladder surveillance is essential in all patients with upper tract urothelial carcinoma, both before and after treatment. This is because the entire urothelium is at risk, and bladder tumors are common in patients with upper tract disease. Cystoscopy is performed periodically to monitor for bladder tumors.
Long-term surveillance after treatment includes periodic imaging (typically CT or MRI of the abdomen and pelvis, and chest imaging), cystoscopy, urine cytology in selected patients, kidney function testing, and clinical assessment. For patients who have undergone kidney-sparing treatment, ureteroscopy is also part of surveillance. Surveillance schedules are individualized based on risk of recurrence and are often intensive in the first several years after treatment.
For patients with confirmed or suspected Lynch syndrome, coordinated care includes genetic counseling, family screening, and surveillance for other cancers associated with the syndrome (particularly colorectal and endometrial cancer). Identifying Lynch syndrome has significant implications for the patient’s ongoing care and for at-risk family members.
Care of kidney function is an important consideration in all patients. Nephron-sparing approaches, when appropriate, preserve kidney function and expand treatment options (including chemotherapy). For patients undergoing radical nephroureterectomy, the remaining kidney bears the full burden of function, and long-term care includes attention to blood pressure control, avoidance of medications that can harm the kidneys, and periodic monitoring of kidney function.
Care during pregnancy or in patients considering pregnancy in the future requires special attention. Some treatments have implications for fertility, and coordination with reproductive medicine when relevant is important.
Care is best coordinated by multidisciplinary teams at centers with experience in urothelial cancer. Imaging, laboratory, pathology, and molecular findings are interpreted alongside the patient’s symptoms, examination, family history, and broader clinical context rather than in isolation.
Patient education plays an essential role. Understanding the diagnosis, the specific characteristics of the tumor, the rationale for the recommended treatment plan, the importance of surveillance, the significance of hereditary syndromes when identified, and warning signs of complications or recurrence all contribute to better outcomes.
Red flag symptoms include severe flank or back pain, high fever with signs of severe urinary tract infection or possible kidney infection (chills, back pain, and nausea), significant decrease in urine output, significant blood in the urine (including clots), severe abdominal pain, unintended weight loss, night sweats, new bone pain, new neurological symptoms, difficulty breathing, or rapid clinical deterioration. These warrant prompt or urgent medical evaluation, as they may indicate acute infection, obstruction, disease progression, or complications of treatment.