Approximately 10% of patients with FAP develop desmoid tumors as part of their extra-colonic manifestations [1]. Although they are histologically benign and typically slow-growing, desmoid tumors do have the capacity to become locally aggressive. Treatment for desmoid tumor is indicated for symptoms, risk to adjacent structures, or cosmesis. In this case, treatment of desmoid tumor was indicated for small bowel obstruction caused by desmoid tumor growth.
Surgical resection with negative pathologic margins is optimal for treatment of most symptomatic desmoid tumors [2]. Post-operative adjuvant radiation therapy may be useful when macroscopic residual tissue is present, particularly in areas with relatively radiation-tolerant surrounding normal tissues. For patients with large tumors or impediments to complete resection, neoadjuvant management with non-cytotoxic or cytotoxic agents may be of benefit. Intra-abdominal desmoids in particular are often not amenable to margin negative resection, and in some instances cytotoxic chemotherapy has achieved favorable results [3, 4] In this case, chemotherapy reduced the size of a tumor causing distal obstruction, allowing bowel resection to resolve an enterocutaneous fistula.
For lesions requiring systemic therapy, hormonal therapy including tamoxifen, toremifine, raloxifene, and progestinal agents have been effective in a subset of patients [5–7]. Non-steroidal anti-inflammatory drugs may be used alone or in combination with tamoxifen [8]. Sulindac is a commonly used NSAID to treat desmoid tumors. Imatinib (Gleevec), a tyrosine kinase inhibitor, has been effective in treatment for desmoid and a phase II multicenter trial investigating the activity of this agent is underway [9, 10].
Cytotoxic chemotherapy is indicated when other measures fail. There can be a significant increase in treatment-related morbidity, which may be justified in some clinical settings. Typically, initial treatment is low-dose systemic chemotherapy to limit side-effects. For instance, treatment with methotrexate and vinblastine given every 7–10 days for several months has stabilized advanced and aggressive disease in some patients [11]. However, responses are often slow and generally occur over many months.
More intensive cytotoxic chemotherapy, such as the combination of doxorubicin and dacarbazine, has been effective in patients who have unresectable disease that is refractory to endocrine therapy, steroids and NSAIDs [12, 13]. Combination chemotherapy using doxorubicin and ifosfamide produced a relatively rapid radiologic and clinical response in our patient.
Although desmoid tumors have no metastatic potential, they may often be locally aggressive, increasing the morbidity and mortality of patients with Gardner's syndrome. As we gain experience in detecting and treating adenomatous disease early, we can expect the extra-colonic manifestations of Gardner's syndrome to play a greater role in the prognosis of these patients. For desmoid tumors, treatment options extend beyond surgical resection, radiation therapy, and non-cytotoxic systemic therapies and can include cytotoxic chemotherapy to the benefit of our patients.