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What is the urachus?

The urachus is a tube-like structure that forms in a developing embryo. It connects the umbilical cord to the urinary bladder before birth. After birth, the urachus usually shrinks into a small ligament. However, traces of the urachus (called urachal residues) can be detected in up to one-third of adults. Urachal residues usually do not cause any symptoms.

What is urachal cancer?

A growth of cancerous cells that starts in the urachus is called urachal cancer.

Because of its location, urachal cancer can grow into the abdominal wall and the abdominal cavity. Often it infiltrates the roof of the urinary bladder. Urachal cancer can grow for a long time before causing symptoms. As a result, it is often detected at later stages.

Fig. 1: Anatomical illustration of an intact (patent) urachus. This situation is very rare in an adult. If urachal residues remain, they are usually partial or microscopic.
Fig. 2: partially patent opening externally, blind internally.
Fig. 2: partially patent opening externally, blind internally.
Fig. 3: partially patent urachas opening internally blind externally.
Fig. 3: partially patent urachas opening internally blind externally.
Fig. 4: Cyst of urachas.
Fig. 4: Cyst of urachas.

Outcome

About 20% of urachal cancer patients cannot be cured by the time they develop symptoms. After treatment, about one-third will have relapse or their disease will spread. Average survival is more than 50% at 5 years.

Symptoms of urachal cancer

Symptoms of urachal cancer become noticeable when the cancer cells grow into surrounding tissue or organs (advanced stage).

Symptoms may include:

  • Blood in the urine (haematuria)
  • Pain
  • Bladder irritation
  • Recurrent bladder infections
  • Mucus from the navel (umbilical discharge) or in the urine (mucusuria)

Diagnosis of urachal cancer

The diagnosis of urachal cancer is usually based on:

  • Blood in the urine
  • A tumour located outside, in the middle, or on top of the urinary bladder
  • Mucus-producing or other cancer cells in the tissue

Physical exam and imaging

An initial diagnosis will include a physical examination, ultrasound of the abdomen, and a urine test (urinary swab test). Urachal cancer is suggested by a tumour located outside, in the middle, or on top of the urinary bladder and blood in the urine.

Diagnostic imaging techniques
Ultrasound Ultrasound is done outside the body (non-invasive) using high-frequency sounds to make an image of the inside of the body.
CT-scan CT stands for Computed Tomography. This imaging technique makes a series of x-ray images of the body.
MRI Magnetic Resonance Imaging uses strong magnetic fields and radio waves to make
images of the body.

Transurethral resection (TUR)

If urachal cancer is suspected, the next step is to examine tissue under a microscope (histologic examination). Surgery must be performed to get the tissue for that examination.

Transurethral resection (TUR) is the most accessible way to acquire tissue from the urinary bladder. TUR is performed by the insertion of a rigid tube-like instrument (endoscope) through the urethra (the canal through which the urine is passed) into the bladder. The tissue is removed with the endoscope. The patient is asleep (under general anaesthesia) during this procedure.

If examination of the tissue shows certain cancerous cells, the diagnosis is then formed in accordance with the imaging results.

Treatment of urachal cancer

Urachal cancer is often diagnosed at later stages.

Based on your disease stage and predicted outcomes, recommended treatment may include:

  • Surgery
  • Chemotherapy
  • New forms of anti-cancer therapy
  • Palliative care

Recommended treatment and predicted outcomes will be based on your cancer stage. The planned treatment approach should be discussed by a multidisciplinary tumour board. This board is made up of practitioners from different medical specialties. They share their different professional opinions to plan appropriate care for individual cancer patients.

Surgery

Tumour removal

Surgery is recommended to remove a urachal cancer tumour that has not spread to other tissues or organs. The tumour will be removed along with surrounding tissue in the abdomen, the navel, and the top of the bladder to make sure no cancer cells remain.

In rare cases, some or all of the urinary bladder must be removed. The pelvic lymph nodes should be removed if imaging shows they are enlarged and/or look like cancer might be present or if they feel suspicious during the operation.

Bladder removal

If parts of your urinary bladder have to be removed, you will have a smaller bladder. This might lead to lower urinary tract symptoms like feeling an urgent need to urinate and frequent voiding. In rare cases, the whole bladder may need to be removed. In this case, a substitute reservoir (neobladder) or an artificial opening for passing urine (urinary stoma) must be built during the operation.

Diagnostic laparoscopy

This procedure may be advised if:

  • You have a large (>4 cm) tumour filled with mucus (mucinous cystic tumour)
  • Images of your abdomen show mucus floating freely

In a diagnostic laparoscopy, the inside of your abdomen is examined with a tube-like camera and one or two additional instruments while you are asleep (under general anaesthesia). If cancerous cells are found, a larger operation will be performed to remove all mucus and tumours, and chemotherapy drugs will be given directly in the abdomen to kill remaining cancer cells.

What to ask your doctor about urachal cancer surgery

  • Why do I need surgery?
  • Will I have to stay in hospital?
  • How long will I be in hospital?
  • What are the possible side effects of the surgery?
  • Will I have any pain?
  • Are there any possible complications?
  • How long will I need to be off work?

Chemotherapy

Systemic chemotherapy is not a substitute for surgical treatment, and it does not provide a cure.

Chemotherapy drugs containing platinum and 5-fluorouracil (5-FU) have shown success in:

  • Urachal cancer that has spread to other tissues or organs
  • Patients with a high risk of recurrence after the operation

What to ask your doctor about urachal cancer chemotherapy:

  • Why do I need chemotherapy?
  • Are there other treatment options besides chemotherapy?
  • Which drugs will I have?
  • How do I take the drugs?
  • Will I have to stay in hospital?
  • How long will I be in hospital?
  • What are the side effects?
  • Can I do anything to help prevent side effects?
  • Who can help me cope with side effects?
  • Who can I contact if I am worried about side effects?
  • What should I do if I get an infection?
  • How long will I have chemotherapy for?
  • How many courses of chemotherapy will I need?
  • How long will I need to be off work?
  • How can you tell if the chemotherapy is working?
  • How long will it take me to recover from the treatment?

Can chemotherapy or radiation before surgery help?

Little is known about the effectiveness of chemotherapy or radiation before surgery for urachal cancer. The most common type of urachal cancer is adenocarcinoma, which is known to respond to chemotherapy or radiation. However, no recommendations can be made at this time.

In addition, little is known about radiotherapy after surgery for urachal cancer, but it does not seem to have a positive effect.

New forms of anti-cancer therapy

In the last years, research has identified some changes in the cells of urachal cancer that might be useful for new forms of anti-cancer therapy, which are known from other cancer types. They might be used in late stages of the tumour, but only little is known about the effectiveness of these new therapies in urachal cancer.

Like with chemotherapy, these new therapies do not substitute for surgical treatment, and do not provide a cure.

Before new forms of anti-cancer therapy can be given, the tumour tissue should be examined for specific molecular changes. The results should be discussed in a multidisciplinary tumour board.

Follow-up after treatment

After the operation, you will be scheduled for doctor visits and imaging at regular intervals (follow-ups). The purpose of these visits is to look for treatment side effects and to scan for possible recurrences.

Early detection of recurrence is crucial to make sure you are treated. A consultation and imaging should be scheduled between one to four times a year for 5 to 10 years after the operation. You should personally look for symptoms like blood or mucus in your urine, abdominal pain, or swelling. If you experience any of these symptoms, please contact your doctor.

Clinical trials

Another option that should be considered are clinical trials. This can be discussed with your doctor as well as when and where trails may be available in your area.

What is a clinical trial?

Clinical studies are typically designed to test how a treatment works among patients with specific characteristics, so not everyone will be eligible.

Why participate in a clinical trial?

Participating in a clinical trial has several advantages. You have the opportunity to be treated with drugs or devices that have been tested for safety and are not widely available. Your symptoms and general condition will also be monitored more often and more closely than during regular treatment.

It also important to know that you can stop your participation at any time. You will not need to explain your reasons.

General information about urachal cancer

Risk factors for urachal cancer

There is a risk of urachal cancer if part of the urachus or the whole urachus is present. Years of chronic inflammation and remodelling or possibly leftover embryologic cells might cause urachal cancer.

An intact urachus is indicated by:

  • Recurrent infections of the navel or bladder
  • Production of mucus by the navel or bladder
  • Navel (umbilical) hernia that has not been identified as a persistent urachus

No other risk factors have been identified yet.

Urachal cancer is very rare. Approximately less than one in 1 million people per year develop urachal cancer, depending on the region of the world. The disease seems to be less common in Europe, for example, than in Japan. Statistically, more men are affected by urachal cancer than women. Most patients are diagnosed in their 50s.

Because of its location, urachal cancer can grow into the abdominal wall and the abdominal cavity. Often it infiltrates the roof of the urinary bladder. Urachal cancer can grow for a long time before causing symptoms. As a result, it is often detected at later stages.

Classification of urachal cancer

Your doctor will classify the severity and aggressiveness of urachal cancer. A cancer stage will be determined
based on:

  • The histologic examination of the tissue
  • The size of the tumour and whether it has grown into surrounding organs or tissue
  • Whether the tumour cells have spread to other organs or tissue (metastases)

Classification by cancer stage guides treatment and prediction of outcomes (prognosis).

This information was produced by the European Association of Urology (EAU) Patient Information Working Group and is based on a narrative review of the literature.

  • Dr. Mark Behrendt, Amsterdam (NL)
  • Dr. Henning Reis, Essen (DE)

This information was updated by the EAU Patient Information Working Group, February 2020.

Links to more information

  • http://urachalcancer.org/
  • https://en.wikipedia.org/wiki/Urachal_cancer
  • https://www.cancercompass.com/message-board/