Last updated:
8/25/2025
Years published: 2008, 2012, 2015, 2018, 2019, 2023, 2025
NORD gratefully acknowledges Valerie Grignol, MD, Associate Professor of Surgery, The Ohio State University-The James Cancer Hospital, Gioconda Alyea, MD (FMG), MS, National Organization for Rare Disorders and the Desmoid Tumor Research Foundation, for assistance in the preparation of this report.
Summary
Desmoid tumor is a rare, non-cancerous (benign) tumor that develops in the fibrous (connective) tissues of the body that connect, support and surround other body parts and organs. Desmoid tumors grow from a fibroblast cell known as myofibroblast, which make up connective tissue and are also important for wound healing. They can develop anywhere in the body. Superficial desmoids tend to be less aggressive than deep desmoids (abdominal, extra abdominal, mesenteric). Desmoid tumors look like dense scar tissue. They adhere to surrounding structures and organs and are often difficult to remove. Surgery has been the traditional therapy for desmoid tumors but up to 20-30% will recur after surgery.
Introduction
Desmoid tumor is called aggressive fibromatosis as it has similarities with a malignant (cancerous) tumor called fibrosarcoma. Desmoid tumors do not spread (metastasize) to other parts of the body.
While each child or adult may experience symptoms differently, the following are the most common symptoms of desmoid tumors. The symptoms vary greatly depending on size and location:
The cause of the desmoid tumor is not known. Desmoid tumors may occur sporadically or may be part of a disease called familial adenomatous polyposis (FAP).
FAP is a familial cancer predisposition syndrome. People with FAP often develop intra-abdominal desmoid tumors as well as abnormal growths called polyps and cancerous tumors in the part of the intestine called the colon. Desmoid tumors that are not part of an inherited condition are described as sporadic. Reports in the medical literature state that 3.5-32% of people with FAP develop desmoid tumors sometime in their life. These desmoid tumors are the result of changes (pathogenic variants) in the adenomatous polyposis coli (APC) gene. FAP is inherited in an autosomal dominant pattern.
However, in most people, the desmoid tumor occurs sporadically, which means that it is not inherited, and it is not caused by a predisposing genetic disease. Variants in the CTNNB1 gene or the APC gene may cause sporadic desmoid tumors. APC gene variants cause desmoid tumors associated with FAP as well as 10% to 15% of sporadic desmoid tumors. Variants in the CTNNB1 gene have been seen in up to 85% of sporadic desmoid tumors. Both genes, APC and CTNNB1, are involved in an important cell signaling pathway that controls the cell growth and cell division as well as the process by which cells mature to carry out specific functions (differentiation).
People who develop sporadic desmoid tumors do not have the other health problems seen in people with FAP who have variants in the APC gene.
Desmoids have been observed in areas of the body where trauma or surgery has occurred, as well as in people taking the female hormone estrogen. However, these factors have not been proven to cause desmoids.
Inheritance
Most desmoid tumors are sporadic and are not inherited. Sporadic tumors result from gene variants that occur in cells other than the reproductive cells (sperm and egg cells) during a person’s lifetime, called somatic variants. Somatic variants in the CTNNB1 or APC gene can cause sporadic desmoid tumors. These gene variants are not inherited.
Desmoid tumors constitute 0.03% of all tumors. The estimated incidence in the general population is 2-4 per million people per year. Desmoid tumors are observed to be more common in people aged 10-40 years but can occur in other age groups. Desmoid tumors can commonly occur in women after childbirth. The female: male gender ratio is 2:1. In children, the incidence is the same in males and females.
To confirm a diagnosis of a desmoid tumor, a biopsy is required. This involves removing a small sample of tissue from the tumor for detailed examination under a microscope. When the biopsy tissue is analyzed, doctors look for specific types of cells known as spindle cells. In desmoid tumors, these cells resemble myofibroblasts which are a type of cell that is important for normal wound healing but usually disappears once healing is complete. In desmoid tumors, however, these cells grow abnormally and persist.
Special laboratory tests, called immunohistochemical stains can identify an important protein known as beta-catenin, which builds up in the cell nucleus due to common genetic changes found in desmoid tumors. This buildup is found in up to 90% of affected people and helps confirm the diagnosis.
Doctors may also test for antibody markers found in the tumor cells, such as smooth muscle actin, desmin and KIT, to help distinguish desmoid tumors from other types of tumors.
Treatment
Treatment for desmoid tumors is based on the size and location of the tumor, how fast it is growing, the presence of symptoms and the overall condition of the affected person.
While surgery was once the first option for treatment, in recent years, medical experts have shifted from immediately using surgery as the first option. Instead, treatment usually begins with an approach called watchful waiting. This means that the tumor is carefully monitored over time using physical examinations and imaging tests such as MRI or CT scans, without starting treatment right away. This strategy is often recommended because desmoid tumors do not spread to other parts of the body and can sometimes shrink or resolve on their own. In fact, up to 20% of patients may have spontaneous tumor regression without active treatment. Because surgery, chemotherapy and radiation therapy can lead to serious complications, including long-term health problems and even life-threatening risks, watchful waiting is considered appropriate for people who have few or no symptoms and whose tumors are stable.
When a desmoid tumor causes significant pain, functional problems, or threaten nearby structures such as blood vessels, nerves, or organs, more active treatment becomes necessary. Treatment options for these patients include medications (systemic therapy), surgery and localized procedures designed to destroy the tumor.
The choice of treatment depends on the location of the desmoid on the body and the side effects of the treatment. This includes short- and long-term complications of the treatment as well as the overall effectiveness of the treatment.
Several medications are now used to treat desmoid tumors and are now considered the first treatment option for people whose tumors are growing and causing worsening symptoms, especially when surgery is not an option. One of the leading drugs is sorafenib, an oral chemotherapy that belongs to a group of treatments known as targeted therapies. These medications work by blocking specific proteins that help tumor cells grow. In clinical trials, sorafenib led to tumor shrinkage in approximately 33% of cases and stopped tumor growth in about 70%. Another drug in the same class, pazopanib, has also shown encouraging outcomes.
In 2023, the U.S. Food and Drug Administration (FDA) approved nirogacestat, the first systemic treatment developed specifically for desmoid tumors. This oral targeted therapy works by blocking a protein that promotes tumor growth. In clinical studies, 71% of people treated with nirogacestat had either stable disease or tumor shrinkage and 41% had a partial or complete response, meaning the tumor either reduced significantly in size or disappeared. People also reported improved quality of life during treatment, making nirogacestat a significant advancement in desmoid tumor care.
If targeted medications are not effective, traditional intravenous chemotherapy may be used. This includes drugs such as doxorubicin (an anthracycline) or combinations like methotrexate and vinblastine. These treatments are typically used when tumors cannot be surgically removed due to their size or location. Although chemotherapy can be effective, it is associated with more severe side effects and is generally considered a second-line option after targeted therapies.
Surgery remains an important tool for managing desmoid tumors in specific patients. It is most suitable for tumors located near the surface of the body and away from vital organs, nerves, or blood vessels. Surgery may also be necessary when the tumor causes complications. However, desmoid tumors tend to recur in up to 30% of patients after surgical removal, and repeated surgeries may be needed. In some people, the tumor may grow back (recur) more aggressively after surgery.
Cryoablation is a new approach to these tumors and is a type of treatment called local ablative therapy. In this treatment, needles are placed into the tumor under image guidance to freeze the tumor and damage the cells causing death of cancer cells. In a clinical trial, 86% of patients had stable disease one year after treatment and symptoms improved. This treatment is best suited for small to moderate size tumors that do not involve vital organs (such as blood vessels, nerves or intestines). It is important to note in the clinical trial this was utilized after people had received at least two medical (systemic) therapies and had not improved.
Radiation therapy, which uses high-energy rays to kill tumor cells, may be considered when tumors recur after other treatments and no longer respond to medications or surgery. It can help reduce tumor size and control symptoms.
Anti-inflammatory drugs may make the tumor slowly shrink. Non-steroidal anti-inflammatory drugs (NSAIDs) alone and in conjunction with other therapies mentioned here have been used to treat desmoid tumors. Some hormones seem to increase the growth of desmoid tumors, so anti-hormonal medications such as anti-estrogens and prostaglandin inhibitors have also been used. Since the advent of targeted therapies with better response rates, the use of NSAIDS and hormone therapy is limited.
After treatment, ongoing monitoring is essential to detect any signs of tumor recurrence. For tumors in the arms and legs, MRI scans are typically used. For tumors located inside the abdomen or chest, CT scans (also known as CAT scans) are preferred to monitor for changes.
Newer substances are being studied that target specific receptors or pathways in desmoid tumors to prevent the growth of tumors.
Researchers are also testing several chemotherapy drugs, or combination of drugs, to determine what is most effective in treating desmoid tumors to avoid radical surgery.
Variants in the gene for beta-catenin have been found to commonly occur in desmoid tumors. Variant analysis may soon be used to predict the risk of recurrence and to aid in the design of individual therapies.
Information on current clinical trials is posted on the Internet at www.clinicaltrials.gov. All studies receiving U.S. government funding, and some supported by private industry, are posted on this government web site.
For information about clinical trials being conducted at the NIH Clinical Center in Bethesda, MD, contact the NIH Patient Recruitment Office:
Toll free: (800) 411-1222
TTY: (866) 411-1010
Email: [email protected]
Some current clinical trials also are posted on the following page on the NORD website:
https://rarediseases.org/for-patients-and-families/information-resources/info-clinical-trials-and-research-studies/
For information about clinical trials sponsored by private sources, contact:
https://www.centerwatch.com/
For information about clinical trials conducted in Europe, contact:
https://www.clinicaltrialsregister.eu/
JOURNAL ARTICLES
Kasper B, Baldini EH, Bonvalot S, et al. Current Management of Desmoid Tumors: A Review. JAMA Oncol. 2024;10(8):1121-1128. doi:10.1001/jamaoncol.2024.1805
Gounder M, Ratan R, Alcindor T, et al. Nirogacestat, a γ-Secretase Inhibitor for Desmoid Tumors. N Engl J Med. 2023;388(10):898-912. doi:10.1056/NEJMoa2210140
Kurtz JE, Buy X, Deschamps F, et al. CRYODESMO-O1: A prospective, open phase II study of cryoablation in desmoid tumour patients progressing after medical treatment. Eur J Cancer. 2021;143:78-87. doi:10.1016/j.ejca.2020.10.035
Desmoid Tumor Working Group. The management of desmoid tumours: A joint global consensus-based guideline approach for adult and paediatric patients. Eur J Cancer. 2020;127:96-107. doi:10.1016/j.ejca.2019.11.013
Gounder MM, Mahoney MR, Van Tine BA, et al. Sorafenib for Advanced and Refractory Desmoid Tumors. N Engl J Med. 2018;379(25):2417-2428. doi:10.1056/NEJMoa1805052
Lev D, Kotilingam D, Wei C, Ballo MT, Zagars GK, Pisters PW, Lazar AA, Patel SR, Benjamin RS, Pollock RE. Optimizing treatment of desmoid tumors. J ClinOnc. 2007;25:1785-1791.
Shi B, Zhu Y, Xu Z, et al. Aggressive fibromatosis in the urological system. Report of two adult patients and review of the literature. Urol Int. 2007;78(1):93-6.
Schwartz RA, Trovato MJ, Lambert PC. The desmoid tumor — a locally aggressive neoplasm. Cesko-SlovenskaDermatologie. 2007;82:34-8.
Neri HA, Villagra EJ, Alvarez AC, et al. Ethmoidal desmoid tumor in a pediatric patient. Otolaryngol Head Neck Surg. 2007;136(1):137-8.
Bhama PK, Chugh R, Baker LH, Doherty GM. Gardner’s syndrome in a 40-year-old woman: successful treatment of locally aggressive desmoid tumors with cytotoxic chemotherapy. World J SurgOncol. 2006;4:96.
Lee JC, Thomas JM, Phillips S, et al. Aggressive fibromatosis: MRI features with pathologic correlation. AJR Am J Roentgenol. 2006;186(1):247-54.
Rajesh A, Sandrasegaran K. Mesenteric desmoid mimicking recurrent testicular cancer. Abdom Imaging. 2005;30(6):777-9.
Mendenhall WM, Zlotecki RA, Morris CG, et al. Aggressive fibromatosis. Am J ClinOncol. 2005;28(2):211-5.
Moon JI, Selvaggi G, Nishida S, et al. Intestinal transplantation for the treatment of neoplastic disease. J SurgOncol. 2005;92(4):284-91.
Erguvan-Dogan B, Dempsey PJ, Ayyar G, Gilcrease MZ. Primary desmoid tumor (extra-abdominal fibromatosis) of the breast. AJR Am J Roentgenol. 2005;185(2):488-9.
Thuret R, Renaudin K, Leclere J, et al. Uncommon malignancies: case 3. Paratesticular desmoplastic small round-cell tumor. J ClinOncol. 2005; 23(25):6253-5.
Brueckl WM, Ballhausen WG, Förtsch T, et al. Genetic testing for germline mutations of the APC gene in patients with apparently sporadic desmoid tumors but a family history of colorectal carcinoma. Dis Colon Rectum. 2005;48(6):1275-81.
Buitendijk S, van de Ven CP, Dumans TG, et al. Pediatric aggressive fibromatosis: a retrospective analysis of 13 patients and review of literature. Cancer. 2005;104(5):1090-9.
Sturt NJ, Gallagher MC, Bassett P, et al. Evidence for genetic predisposition to desmoidtumours in familial adenomatous polyposis independent of the germline APC mutation. Gut. 2004; 53(12):1832-6.
Lindor NM, Dozois R, Nelson H, Wolff B, King J, Boardman L, Wilson M, Greene MH, Karnes W, Mesa R, Welch T, Edmonson J, Limburg P. Desmoid tumors in familial adenomatous polyposis: a pilot project evaluating efficacy of treatment with pirfenidone. Am J Gastroenterol. 2003; 98(8):1868-74.
Dormans JP, Spiegel D, Meyer J, et al. Fibromatoses in childhood: the desmoid/fibromatosis complex. Med PediatrOncol. 2001;37(2):126-31.
Abdelkader M, Riad M, Williams A. Aggressive fibromatosis of the head and neck (desmoidtumours). J Laryngol Otol. 2001;115(10):772-6.
Rai AT, Nguyen TP, Hogg JP, Gabriele FJ. Aggressive fibromatosis of the neck in a patient with Gardner’s syndrome. Neuroradiology. 2001; 43(8):650-2.
Shields CJ, Winter DC, Kirwan WO, Redmond HP. Desmoidtumours. Eur J SurgOncol. 2001; 27(8):701-6.
INTERNET
Schwartz RA, Lambert PC. Desmoid Tumor. Medscape. Updated Nov 28, 2023. https://emedicine.medscape.com/article/1060887-overview Accessed August 4, 2025.
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