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Health condition · Clinically reviewed

Desmoid tumours, active surveillance, targeted systemic therapy and the arrival of nirogacestat.

A rare, locally infiltrative but non-metastasising fibroblastic tumour. Care has shifted from routine surgery to watchful monitoring in a sarcoma centre, with tyrosine kinase inhibitors and gamma-secretase inhibition when disease progresses.

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A radiographer guides a patient onto the bed of an advanced 3 Tesla MRI scanner in a London imaging suite

Why trust this guide

  • 01

    Clinically reviewed

    Written by our editorial team and reviewed by a registered UK clinician before publication.

  • 02

    Sourced from guidance

    Aligned with the 2020 international consensus, ESMO, NCCN and UK sarcoma network standards.

  • 03

    Current for 2026

    Reflects active surveillance as first-line, sorafenib evidence and the arrival of nirogacestat (Ogsiveo).

Key facts

Desmoid tumours at a glance.

The essentials in plain English - what a desmoid tumour is, where it appears, and how UK sarcoma centres treat it today.

  • What it is

    A rare monoclonal fibroblastic proliferation, locally infiltrative but never metastasising, driven by CTNNB1 or APC pathway changes.

  • How common

    Around 5 to 6 cases per million people per year, most often diagnosed between 15 and 60 with a female-to-male ratio near 2:1.

  • Where it appears

    Abdominal wall (about half, often pregnancy-related), intra-abdominal (FAP-linked) and extra-abdominal at the shoulder, chest wall, back, limbs or head and neck.

  • Genetics

    CTNNB1 mutations (S45F, T41A, S45P) in around 90% of sporadic tumours; APC mutations in FAP-associated disease.

  • First-line care

    Active surveillance for asymptomatic disease, with MRI every three to six months and treatment reserved for progression.

  • New options

    Nirogacestat (Ogsiveo), a gamma-secretase Notch inhibitor, was FDA-approved in 2023 for progressive desmoid tumours; MHRA and NICE decisions are pending.

Why this guide matters

A rare tumour, a specialist plan.

Care has changed a lot in the last ten years. Three principles now guide almost every UK plan.

  • Active surveillance first

    Many desmoid tumours stabilise or regress. Watching with MRI avoids the high recurrence rate that comes with routine surgery.

  • A sarcoma MDT is essential

    UK supra-regional centres bring together radiology, pathology, molecular testing, surgery, oncology and interventional radiology.

  • The drug landscape is moving

    Sorafenib has strong trial evidence, and nirogacestat is the first drug licensed specifically for desmoid tumours in the US.

How the diagnosis is made

From first lump to a shared MDT plan.

The steps a UK sarcoma service typically takes, in order, so you know what to expect and why.

  1. 01

    Assessing

    Clinical assessment

    A slowly enlarging, deep, firm and poorly circumscribed mass, sometimes painful, and often present for months before scan.

  2. 02

    Assessing

    Pregnancy and family history

    Pregnancy, prior surgery or trauma, and any personal or family history of polyposis, colorectal cancer or Gardner features.

  3. 03

    Assessing

    MRI - the gold standard

    Infiltrative margins, heterogeneous T2 signal and gadolinium enhancement give a strong radiological signature.

  4. 04

    Confirming

    Image-guided core biopsy

    A specialist sarcoma centre core biopsy with beta-catenin immunohistochemistry (nuclear positivity in about 80%).

  5. 05

    Confirming

    CTNNB1 molecular testing

    Sequencing for S45F, T41A and S45P confirms the diagnosis and helps predict behaviour.

  6. 06

    Confirming

    FAP screening if suspected

    Colonoscopy and APC germline testing for anyone with intra-abdominal disease, young onset or Gardner features.

  7. 07

    Planning

    Sarcoma MDT review

    Referral to a UK supra-regional centre (Royal Marsden, Bristol, Birmingham, Newcastle, Leeds, Nottingham, Oxford, Cambridge, Manchester or Sheffield) for a shared plan.

Typical timeline: from first scan to a settled surveillance or treatment plan in weeks, not months.

Symptoms

What a desmoid tumour actually looks like.

The presentation depends heavily on site. A firm slow-growing mass is the classic finding, but intra-abdominal disease can behave very differently.

  • Slowly enlarging deep mass

    A firm, poorly defined lump that grows over months, often noticed by chance or after minor trauma.

  • Local pain or tenderness

    Discomfort where the tumour presses on nerves, muscle or bowel, sometimes worse with movement.

  • Abdominal wall lesion

    The most common site in young women, often appearing during or after pregnancy near a scar or the rectus sheath.

  • Intra-abdominal disease

    Can cause bowel obstruction, ischaemia, hydronephrosis or fistula, and is potentially life-threatening in FAP.

  • Extra-abdominal sites

    Shoulder, chest wall, back, limbs and head and neck, sometimes limiting movement or nerve function.

  • Post-surgical recurrence

    Regrowth at a previous excision site is common, which is one reason surgery is no longer routinely first-line.

  • Gardner features

    Osteomas, epidermoid cysts and dental anomalies alongside polyposis suggest the Gardner variant of FAP.

  • Red flag - rapid growth or obstruction

    Fast enlargement, bowel obstruction or new nerve symptoms need urgent sarcoma MDT review.

Treatment

How desmoid tumours are treated in the UK.

Active surveillance first for most, systemic therapy for progressive disease, and surgery, radiotherapy or ablation reserved for symptomatic or resistant cases.

  • Active surveillance

    The first-line approach in international consensus - many desmoid tumours stabilise or regress. MRI every three to six months, treatment reserved for progression.

  • Surgery

    Kept for symptomatic disease that has failed other options. Recurrence rates of 20 to 50% mean it is no longer the default first step.

  • Sorafenib

    A tyrosine kinase inhibitor with strong evidence from the Alliance A091105 trial (2018), showing around 81% progression-free survival at two years.

  • Pazopanib and imatinib

    Alternative tyrosine kinase inhibitors used when sorafenib is not tolerated or available, guided by MDT preference and patient factors.

  • Nirogacestat (Ogsiveo)

    A gamma-secretase Notch inhibitor, FDA-approved in 2023 as the first drug specifically licensed for progressive desmoid tumours. MHRA, EMA and NICE reviews are ongoing.

  • Low-dose chemotherapy

    Weekly methotrexate with vinblastine over many months, or pegylated liposomal doxorubicin, for progressive or symptomatic disease.

  • Hormonal and NSAID options

    Tamoxifen, toremifene and historically sulindac have been used with limited evidence, sometimes as adjuncts in slow-growing disease.

  • Radiotherapy and ablation

    Radiotherapy for unresectable disease that has failed systemic options; cryoablation, HIFU and RFA are emerging image-guided alternatives.

What this guide is based on

The sources behind every claim on this page.

International consensus, ESMO and NCCN guidelines and the pivotal trials that shaped current care.

Key references

Guidelines and trials we relied on.

A quiet reminder

This guide is for information, not medical advice.

Your sarcoma MDT knows your imaging, molecular profile and history and can tell you which parts apply to you.

  • Desmoid Tumor Working Group. The management of desmoid tumours: a joint global consensus-based guideline (European Journal of Cancer, 2020).

  • ESMO/EURACAN/GENTURIS Clinical Practice Guidelines. Soft tissue and visceral sarcomas, desmoid section.

  • NCCN Clinical Practice Guidelines in Oncology. Soft Tissue Sarcoma - Desmoid Tumors.

  • Alliance A091105 (Gounder et al., New England Journal of Medicine, 2018). Sorafenib for progressive desmoid tumours.

  • DeFi trial (Gounder et al., New England Journal of Medicine, 2023). Nirogacestat in adults with desmoid tumours.

  • British Sarcoma Group. Standards for the management of soft tissue sarcomas in the UK.

Red flags

When a desmoid tumour needs urgent attention.

Most surveillance is uneventful. These are the situations that break the pattern and deserve a same-week or same-day call to your sarcoma team.

  • Bowel obstruction

    New abdominal distension, vomiting or absolute constipation in a person with intra-abdominal disease needs same-day hospital review.

  • Hydronephrosis or renal pain

    Flank pain, reduced urine output or new hypertension can signal ureteric compression and needs urgent imaging.

  • Fistula or bowel perforation

    Faeculent discharge, sepsis or peritonism is a surgical emergency, particularly in FAP-associated disease.

  • Rapid tumour growth

    A clear jump in size or new pain between scans should trigger an earlier MDT review rather than waiting for the next planned MRI.

  • New neurological deficit

    Weakness, numbness or foot drop from a shoulder, chest wall or limb tumour needs prompt specialist assessment.

  • Pregnancy planning

    Desmoid tumours can grow during pregnancy - counselling and shared decision-making with sarcoma and obstetric teams should happen before conception where possible.

  • FAP without colonoscopy

    Anyone with an APC mutation or Gardner features who has not had recent colonoscopy needs an urgent specialist FAP-desmoid clinic review.

  • Uncontrolled pain

    Pain that opioids are not controlling deserves specialist palliative care input alongside sarcoma MDT review.

  • Sudden weight loss or systemic upset

    Unintentional weight loss, fever or night sweats are unusual in desmoid disease and warrant a rethink of the diagnosis.

Living with it

A rare tumour, but a well-worn path.

Four things that make the biggest difference: sticking with surveillance, staying in a sarcoma centre, leaning on patient networks, and speaking up when something changes.

A quiet reminder

Watching is a treatment, not a delay.

Structured MRI surveillance protects you from the cost of surgery that may not have been needed.

  1. 01 Watchful

    Trust the surveillance plan

    Many tumours stabilise or shrink without treatment. Sticking to the MRI schedule is doing something, not nothing.

  2. 02 Team

    Stay in a sarcoma centre

    Care in a UK supra-regional sarcoma MDT gives access to trials, ablation, systemic therapy and rare-disease expertise.

  3. 03 Support

    Use the patient networks

    The Desmoid Tumour Research Foundation, Sarcoma UK and the FAP Support Group all offer peer support and up-to-date treatment information.

  4. 04 Escalate

    Speak up early if things change

    New pain, faster growth or bowel symptoms are reasons to contact your team between scans, not to wait for the next appointment.

Frequently asked

Everything we get asked about desmoid tumours.

Quick answers on surveillance, systemic therapy, FAP links and pregnancy planning.

  • What is a desmoid tumour?

    A desmoid tumour, also called aggressive fibromatosis or desmoid-type fibromatosis, is a rare monoclonal fibroblastic proliferation. It grows into surrounding tissues and can recur locally, but unlike cancer it never spreads to distant sites.

  • Is a desmoid tumour cancer?

    It is not classified as cancer because it does not metastasise. However, it can behave aggressively locally, damaging nerves, muscle and bowel, and it is managed within sarcoma services because of that behaviour.

  • Why is active surveillance now first-line?

    Studies show that 20 to 30% of desmoid tumours regress spontaneously, 30 to 50% stay stable, and only 20 to 30% clearly progress. Active surveillance with MRI every three to six months avoids unnecessary surgery and its high recurrence rate.

  • What treatments are available if my tumour progresses?

    Options include tyrosine kinase inhibitors such as sorafenib and pazopanib, low-dose chemotherapy with methotrexate and vinblastine, radiotherapy, image-guided ablation and, where available, nirogacestat (Ogsiveo), a gamma-secretase inhibitor approved in the US in 2023.

  • Is a desmoid tumour linked to familial adenomatous polyposis (FAP)?

    Around 5 to 10% of desmoid tumours are FAP-associated and carry an APC mutation. Intra-abdominal disease, young onset, or Gardner features such as osteomas and epidermoid cysts should prompt colonoscopy and germline APC testing.

  • Can I still get pregnant with a desmoid tumour?

    Yes, but pregnancy can influence tumour behaviour. Shared decision-making with your sarcoma MDT, obstetric team and, where relevant, clinical geneticists helps you plan timing, monitoring and delivery safely.

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