Urachal cancer: a rare cancer arising near the top of the bladder

Before birth, a narrow channel called the urachus connects the developing bladder to the navel. A pathology paper explains that after the third trimester it normally shrinks into a fibrous cord, though a remnant can still be found in about a third of adults. Cancer can arise from the lining of that remnant. Because it begins at the top (dome) of the bladder and outside the inner bladder lining, urachal cancer behaves differently from the usual bladder cancer, which starts in the lining.

Almost all urachal cancers are adenocarcinomas, which arise from gland-type cells and often produce mucus. In a series of 46 patients, all tumours were adenocarcinomas, most of the mucinous type, and 44 were located at the dome. A case report states that urachal cancer accounts for 0.01% of all cancers in adults. The pathology paper says it accounts for less than 1% of all bladder cancers. Because it is so rare, most doctors will see only a handful in a career.

The case report states that haematuria, or blood in the urine, is the most common presentation. The NHS lists the main symptom of bladder cancer as blood in your pee, with other symptoms including pain or stinging when peeing, getting lots of urinary tract infections, needing to pee more often or very suddenly, loss of appetite and weight loss, back and lower tummy pain, bone pain and tiredness. Cancer Research UK says blood in the urine may be pink, red or sometimes dark brown, may come and go, and is not usually painful.

Urachal tumours can also cause features that bladder cancers rarely do. In one reported case, a man had an ulcerating swelling with foul-smelling discharge in the lower abdomen below the navel, along with blood in the urine, passing urine more often, loss of appetite and weight loss. The pathology study notes that most tumours present at an advanced stage.

The NHS says to ask for an urgent GP appointment or get help from NHS 111 if you have blood in your pee, even if you do not have any other symptoms, it is the first time it has happened, there is only a small amount of blood, or you are not sure if it is blood. Do not wait to see whether it comes back. Cancer Research UK likewise says to see your GP if you ever see blood in your urine.

Most people with blood in the urine do not have cancer, since urine infections and other conditions are far more common, but it always needs checking. A new lump or discharge in the lower abdomen, or unexplained weight loss, should also be reported.

Your GP will take a history, examine you and may check a urine sample and blood tests, then refer you to urology if cancer is possible. The NHS says this may be an urgent referral, which does not definitely mean you have cancer.

Specialist assessment typically includes cystoscopy, a camera test of the bladder with biopsies, and CT or MRI scans to see the tumour, its relationship to the bladder wall and navel, and whether it has spread. In the case report, ultrasound and contrast CT showed a mass on the front wall and dome of the bladder, with cystoscopy and biopsy confirming adenocarcinoma. A key task is to show the tumour is primary urachal rather than a bladder adenocarcinoma or a spread from another organ such as the bowel, so pathologists look at the location, the cell type and special stains, and imaging or colonoscopy may exclude a bowel primary.

Because urachal cancer is rare and treatment decisions are complex, referral to a specialist cancer centre or a team that discusses such cases in a multidisciplinary meeting is common.

The case report states that surgery is currently the treatment of choice. The gold standard operation includes excision of the urachus and navel along with partial or radical cystectomy (removal of part or all of the bladder), combined with removal of pelvic lymph nodes on both sides. If the whole bladder is removed, a urinary diversion is created, for instance an ileal conduit, in which a section of bowel carries urine to a stoma on the abdomen.

The role of chemotherapy and radiotherapy is less well established. The case report says the effectiveness of adjuvant or neoadjuvant chemotherapy, largely based on 5-fluorouracil and cisplatin, is not yet established, and that its use is generally limited to patients with positive margins or metastatic disease, with choices based on isolated case reports. Recurrence and advanced disease are managed by an oncology team, and clinical trials may be an option.

Surgical margin status is the most significant predictor of prognosis according to the same report, which is why complete excision is the aim.

Outlook depends mainly on how far the cancer has spread at diagnosis and whether it can be removed completely. In the 46-case pathology study, 25 patients had died of cancer after a mean of 32 months, and 21 were alive after a mean of 65 months. The median cancer-specific survival of urachal adenocarcinoma patients was 45 months, which was longer than that of bladder urothelial carcinoma patients with similar-stage disease. Those figures come from the cases of one institution, so they cannot predict an individual outcome.

Follow-up involves regular examinations and scans for years, because recurrence can happen in the pelvis, abdominal wall or elsewhere. Your specialist team will explain the schedule.

Being diagnosed with a rare cancer can feel isolating, with little patient literature available. Ask your team for a clinical nurse specialist as a named contact, and consider general bladder cancer and cancer support organisations such as Cancer Research UK and Macmillan Cancer Support, which provide helplines and information, although their pages usually cover common bladder cancer rather than urachal cancer specifically.

After a cystectomy, specialist stoma nurses teach stoma care and a dietitian and physiotherapist help with recovery. Emotional support, including counselling, is an important part of care.

No NHS or UK charity patient page specifically on urachal cancer was found at the time of writing. The statements about urachal cancer on this page come from published case reports and a pathology series, which are international and describe small numbers of patients, so they are background information rather than UK guidance. NHS and Cancer Research UK pages are cited only for bladder cancer symptoms and what to do about blood in the urine.