Desmoid Tumours

What is a desmoid tumour? 

  • Desmoids are benign (non-cancerous) tumours/lumps that are seen fairly frequently in patients with familial adenomatous polyposis (FAP). Up to 15% of patients with FAP develop a desmoid tumour. 
  • They can occur in anyone but they are seen rarely in the general population. In people with FAP they are nearly 1000 times more common. 

What are the symptoms of a desmoid? 

  • In most instances they present only as a painless lump. In the abdomen they may cause pain and/or swelling. If they press on the bowel they can cause a blockage that may lead to difficulty opening the bowels/passing flatus and nausea/vomiting. Rarely (in severe cases) they can cause a hole in the bowel and infection in the abdomen. 

Where do they occur? 

  • Most FAP associated desmoids are found inside the abdomen or in abdominal musculature but can occur anywhere in the body 

Why do they occur? 

  • We do not yet know why some people get them and others do not. There are some recognised risk factors for their occurrence 

Desmoid risk factors: 

  • Female gender – women are almost twice as likely as men to get desmoid 
  • Tissue injury including surgery itself. This is unavoidable for most with FAP as they need surgery to remove the large bowel for their polyposis. Desmoids typically occur within 3 years of surgery although some develop before and without a history of trauma 
  • Certain FAP gene mutations can increase the chance of a desmoid developing 
  • A family history of desmoid increases the chance of developing one 

Why do desmoids cause problems? 

  • The vast majority of desmoids do not cause any problems and may be found by chance (when patients are scanned for other reasons) or present only as a lump with no other symptoms 
  • Occasionally they do cause complications and this is usually due to excessive growth. Sometimes they press onto structures nearby. In the abdomen this may involve small bowel, blood vessels or ureters (tubes draining urine from kidneys to bladder). 



  • NONE just observe 

The majority of desmoids require no treatment at all and people can live a normal life with them. Sometimes these lumps may disappear spontaneously but many remain as they are. It is important that your hospital team keep an eye on the desmoid and will usually use scans in the early stages to monitor for growth and any complications 

  • Medication

In cases where desmoids grow quickly or press on the bowel/ureters, medication is usually recommended. This would start with an anti-inflammatory medication called sulindac. Anti-oestrogen drugs, such as raloxifene, may also be incorporated into the treatment plan. These medications are reported to be around 50% effective in controlling desmoid growth 

  • Surgery

This is usually a last resort. Remember, trauma can be a risk factor for desmoids so surgery can induce growth. This is why your doctor may not suggest surgery from the outset. In a few instances surgery is unavoidable. It may be used to remove the desmoid completely (e.g. if it is on the outside of the abdomen) but in most cases this is not possible due to risk of damaging nearby organs/tissues. Other forms of surgery may involve diverting bowel away from the blockage by bringing part of it to the surface of the abdomen (stoma) or bypassing the part of the bowel that is blocked. 

  • Other treatments 

Chemotherapy – Although desmoids are not cancerous, this is sometimes offered for fast growing desmoids where surgery is not possible or very difficult 

Radiotherapy – this has been used for some desmoids but experience is limited and must be used with caution around the abdomen where bowel can be damaged inadvertently 

Parenteral nutrition– this is when liquid nutrition is given to a person through a drip into a vein. This may be required when a patient cannot absorb enough food from the small bowel due to desmoid 

Ureteric stenting – If the ureter is blocked by a desmoid a plastic tube (a stent) may need to be placed inside the ureter to keep it open so it can continue to drain urine from the kidney. Stents will likely be required long-term in such cases and will need changing every 4-6 months


  • Why do we not know more about Desmoids?

Because they are so rare and the majority do not cause significant complications, it is difficult to study desmoids. We cannot carry out drug trials because too few people are affected and some desmoids disappear completely while others remain stable for many years. It is therefore difficult to assess if a treatment has really worked or whether the desmoid would have just stopped growing on its own without treatment. Desmoids are also extremely difficult to grow in the laboratory so drug testing here is not easy either. 

  • Does anyone out there care?

YES! We are continuing to research into desmoids and so do other researchers in other countries. If you would like to be involved more please contact Polypeople or enquire with medical staff when you come to your clinic appointment. If you would like to know more we will post future advances in desmoid research on this website. 

We are also trying to set up a desmoid support group for those who are interested. At a recent desmoid group meeting it was apparent that people felt isolated and knew very little about their condition. They wanted to talk to others affected by it and had found this difficult to do. So please get involved through this website! 

Finally, don’t forget you can get a full update on polyposis research at the annual Polyposis Information Day (next one scheduled for 15th September 2018), St Mark’s Hospital. For more information follow the links on this website. 

Miss Sarah-Jane Walton 

Desmoid researcher, The Polyposis Registry, St Mark’s Hospital