Desmoid tumors
Desmoid tumors, also referred to as aggressive fibromatosis, are benign growths that arise from the tissue surrounding muscles, commonly found in the abdominal area. While these tumors can develop anywhere in the body, they are most often associated with certain risk factors, including familial adenomatous polyposis (FAP), surgical trauma, pregnancy, and exposure to high hormone levels. The exact cause of desmoid tumors often remains unknown, but genetic mutations, particularly in the APC and CTNNB1 genes, play a significant role in their development.
Incidence rates are low, with approximately 2 to 4 cases per million people each year, and they are more commonly diagnosed in women, particularly those in their thirties and forties. Symptoms may vary, but desmoid tumors are typically painless, occasionally causing discomfort if they affect nearby nerves or organs. Diagnosis involves imaging techniques like ultrasound, CT scans, or MRIs, followed by biopsy.
Treatment usually starts with surgical removal, though radiation and various drug therapies can be effective alternatives or adjuncts, particularly if surgery is not feasible. In 2023, the FDA approved Nirogacestat, a new oral treatment that has demonstrated positive results in managing tumor size and improving patients’ quality of life. While desmoid tumors do not metastasize, they can be locally aggressive, and recurrence is a significant concern, necessitating careful monitoring.
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Subject Terms
Desmoid tumors
ALSO KNOWN AS: Aggressive fibromatosis
RELATED CONDITIONS:Familial adenomatous polyposis (FAP), Gardner syndrome
DEFINITION: Desmoid tumors are tumors of the tissue surrounding muscle that may develop anywhere in the body but are often found in the abdomen.
Risk factors: Familial adenomatous polyposis (FAP), an inherited syndrome in which thousands of polyps are found in the colon, is a , as are surgical trauma, pregnancy and childbirth, and exposure to high levels of hormones.
Etiology and the disease process: In many cases, the cause of desmoid tumors is not known. However, they may be related to trauma (especially surgical trauma) or to hormones. There is a known genetic association between desmoid tumors and familial adenomatous polyposis, which is most often caused by mutations in the APC gene. In addition, somatic (that is, acquired rather than inherited) mutations in the CTNNB1 gene have been found in approximately 85 percent of non-inherited desmoid tumors.
Incidence: Desmoid tumors are uncommon, with an approximate annual incidence of 2 to 4 cases per one million people. They are slightly more common in women than in men and are usually found in individuals in their thirties and forties, although they may develop between the ages of fifteen and sixty. They are highly uncommon in children and those over sixty. Individuals with familial adenomatous polyposis have an estimated 10 to 20 percent chance of developing a desmoid tumor.
Symptoms: A desmoid tumor is usually a painless mass. It may be felt as a lump. Pain may develop if nerves, muscles, or organs are affected by the growing tumor. Tumors in the abdomen can cause abdominal pain, a change in bowel habits, or rectal bleeding.
Screening and diagnosis: Ultrasound imaging is used initially to examine soft-tissue tumors. A computed tomography (CT) scan or magnetic resonance imaging (MRI) may be used subsequently. The diagnosis of desmoid tumor is made by biopsy. Analysis of the CTNNB1 gene may also contribute to a diagnosis.
Treatment and therapy: Surgery to remove the tumor has long been the preferred treatment, but radiation or drug therapy may also be used either alone (if the tumor is inoperable) or in combination with surgery. Radiation alone or radiation combined with surgery tends to produce better results than surgery alone as surgery can be challenging depending on the location of the tumor. If radiation and surgery are insufficient or contraindicated, potential drug therapies include nonsteroidal anti-inflammatory drugs (NSAIDs) such as sulindac and indomethacin, COX-2-selective NSAIDs such as celecoxib, tyrosine kinase inhibitors such as imatinib and sorafenib, and hormonal therapies such as tamoxifen. Traditional cytotoxic chemotherapies, such as doxorubicin and methotrexate, may be indicated when other therapies have failed or when the tumor is fast-growing or causes symptoms. If there are no symptoms, watchful waiting (observation without treatment) may be recommended before surgery or radiotherapy.
In 2023, Nirogacestat, an oral gamma secretase inhibitor, was approved by the U.S. Food and Drug Administration (FDA) for treatment of desmoid tumors. Nirogacestat treatments have shown marked improvements in not only tumor size and growth, but also quality of life for patients since the tumors can often impact everyday functioning due to pain or pressure on other parts of the body.
Prognosis, prevention, and outcomes: Desmoid tumors are benign and very rarely spread from the site of the original tumor. However, they are locally aggressive and potentially life-threatening if located near vital organs, and local recurrence rates can be as high as 79 percent. Recurrence is monitored by repeat MRI. Individuals with desmoid tumors should be tested for mutations of the APC gene.
Bibliography
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