What should a patient with an abdominal wall desmoid tumor be screened for?

From the Guidelines

A patient with abdominal wall desmoid tumor should be screened for colon polyps (option b). Desmoid tumors, particularly those in the abdominal wall, are strongly associated with Familial Adenomatous Polyposis (FAP) syndrome, which is characterized by numerous colon polyps that have a high risk of malignant transformation [ 1 ]. FAP is caused by mutations in the APC gene, which also predisposes patients to desmoid tumors. These desmoid tumors occur in approximately 10-15% of FAP patients and may sometimes be the first manifestation of the syndrome. The screening should include a colonoscopy to detect and remove any polyps before they progress to colorectal cancer. Early detection of colon polyps in these patients is crucial as nearly 100% of untreated FAP patients will develop colorectal cancer by age 40 [ 1 ]. Even in sporadic (non-FAP) desmoid tumors, screening for colon polyps is prudent due to the potential genetic overlap and increased risk. The screening should begin at diagnosis of the desmoid tumor if not already performed.

Some key points to consider in the management of these patients include:

• The role of elective surgery for intra-abdominal desmoids should be restricted to treating secondary effects of the desmoid disease, and this surgery should be performed in expert centres [ 1 ].
• Sulindac in combination with high-dose selective oestrogen receptor modulators may be effective in FAP patients with intra-abdominal desmoids and desmoids located at the abdominal wall [ 1 ].
• FAP patients should be counselled about the risk of postoperative desmoid disease formation [ 1 ].
• Determining genotypes or family history of desmoid disease may be predictive of desmoid formation [ 1 ].
• Annual thyroid examinations should begin in the late teen years, and annual thyroid ultrasounds can be considered [ 1 ].
• Abdominopelvic MRI 1 to 3 years following colectomy and then every 5 to 10 years may be considered to evaluate for the development of desmoid tumors in families with a positive family history of desmoid tumors [ 1 ].

It is essential to prioritize the screening for colon polyps in patients with abdominal wall desmoid tumors due to the strong association with FAP syndrome and the high risk of malignant transformation.

From the Research

Screening for Abdominal Wall Desmoid Tumor

A patient with abdominal wall desmoid tumor should be screened for:

• Colon polyps, as desmoid tumors are associated with familial adenomatous polyposis (FAP), a condition that increases the risk of colon cancer 2, 3, 4, 5, 6

Associated Conditions

The following conditions are associated with desmoid tumors:

• Familial adenomatous polyposis (FAP) 2, 3, 4, 5, 6
• APC mutation 4
• Family history of desmoid tumors 4

Screening Recommendations

Based on the available evidence, the following screening recommendations can be made:

• Colonoscopy should be performed to screen for colon polyps and FAP 5
• APC germline test should be considered in patients with desmoid tumors, especially those with a family history of FAP or desmoid tumors 5
• CTNNB1 molecular testing should be performed in all cases of newly diagnosed desmoid tumors to rule out FAP-associated desmoid tumors 5