[Kok! Health] 0.6% of All Cancers... 'Unknown Cancer' Shinwoo Ureteral Cancer

Survival Rate Below 50% for Stage 3 or Higher

[Asia Economy Reporter Kim Young-won] Upper tract urothelial carcinoma (UTUC) is a rare cancer in South Korea, accounting for only 0.6% (1,444 cases) of all cancer occurrences in 2019. Due to its rarity, it is not well known, but it requires caution as it rapidly metastasizes to other tissues. When UTUC progresses to stage 3, about half of the patients die within five years.

Urine produced in the kidney temporarily collects in the renal pelvis before flowing through the ureter to the bladder. Cancer arising from the epithelium of the urinary tract, where urine flows, is called urothelial carcinoma. When the carcinoma occurs in the bladder, it is called bladder cancer; when it occurs in the renal pelvis or ureter, it is called upper tract urothelial carcinoma. Most urothelial carcinomas occur in the bladder, with only 5-10% arising in the renal pelvis and ureter. UTUC frequently occurs in people over their 70s and is twice as common in men compared to women.

At diagnosis, 66% of UTUC cases are invasive diseases, and 10-20% are found with metastasis. Depending on the extent of cancer cell invasion into surrounding tissues, the disease is classified as superficial or invasive. Compared to superficial disease, which is limited to the mucosa, invasive disease that invades the muscle layer has a poorer prognosis.

Smoking increases risk sevenfold... Common symptom is 'hematuria'

The main risk factors are smoking and aristolochic acid. Smoking can increase the risk of UTUC by about seven times. Aristolochic acid, found in some herbs and traditional medicines, is a nephrotoxic substance known to cause bladder cancer in about 1 in 10 exposed individuals. Repeated alcohol consumption equivalent to about one glass of soju per day also influences disease development.

The most common symptom of UTUC is hematuria. Approximately 70% of patients have visible or microscopic blood in the urine. Flank pain is also commonly observed in 20-30% of patients. Blood clots formed due to hematuria can block the ureter or disrupt urine flow, causing flank pain. Other systemic symptoms related to cancer, such as weight loss, fatigue, fever, and cold sweats, may also accompany the disease.

The basic diagnostic methods for UTUC are blood and urine tests. Additionally, CT or MRI scans are performed. For ureteral cancer, which occurs in the ureter, ureteroscopy and biopsy are conducted. Since about 17% of UTUC patients also have bladder cancer, cystoscopy is also performed.

Treated surgically but prognosis is poor

The primary treatment for UTUC is surgical resection. A representative surgical method is 'radical nephroureterectomy,' which involves removing the kidney located above the renal pelvis and ureter with cancer, along with part of the bladder including the ureteral orifice. Lymph nodes in the surrounding area may also be removed if necessary. Recently, 'segmental ureterectomy' has been increasingly performed. When cancer is only in the lower ureter, this method allows removal of the cancerous area while preserving the kidney.

For some low-risk patients with cancer in the renal pelvis, endoscopic treatment may be considered. This treatment involves using a laser to ablate the cancer through an endoscope and is only performed on a small number of patients due to the high risk of recurrence.

However, UTUC has a 30% chance of recurrence in the bladder and a 10% chance of recurrence in the contralateral renal pelvis or ureter after surgery. For stage 3 or higher UTUC, the 5-year survival rate is about 50%, indicating a poor prognosis. Therefore, careful and long-term follow-up is necessary even after surgery. Typically, follow-up is conducted every 3-6 months for the first 5 years post-surgery and annually up to 10 years.

Professor Yuk Hyung-dong of the Department of Urology at Seoul National University Hospital explained, "UTUC rarely shows specific symptoms in the early stages, making early detection difficult, and 10-20% of cases are found with metastasis to other organs at diagnosis." He added, "Since prevention is important, smokers should definitely quit smoking and undergo regular annual check-ups including urine tests, abdominal CT, and abdominal ultrasound. If suspicious symptoms such as hematuria or flank pain appear, it is crucial to visit a hospital immediately."

Yook Hyung-dong, Professor of Urology at Seoul National University Hospital.

This content was produced with the assistance of AI translation services.