Desmoid Tumors and Current Status of Management
Section snippets
History and epidemiology
Desmoid tumors account for about 0.03% of all neoplasms and less than 3% of all soft tissue tumors [1]. They were first described in 1832 by MacFarlane [2] of the Royal Glasgow Infirmary [3]. The term desmoid originates from the Greek word “desmos,” meaning band or tendon-like, and was first applied by Muller [4] to describe tumors with a tendon-like consistency [3].
It remains a rare tumor, with only an estimated 900 new cases diagnosed each year in the United States, or 3 to 4 cases per 1
Etiology
The etiology is still an enigma, but desmoids appear to involve a deregulation of connective tissue growth, and the biologic potential of each tumor lesion varies [9]. It is difficult to define the risk factors, considering the rarity and heterogeneity of growth patterns in these lesions. Alman and colleagues [9] identified an abnormal expression of c-sis and platelet-derived growth factor and proposed a mechanism by which inappropriate expression of c-sis can lead to increased production of
Pathology
Desmoid tumors can arise from any body site and infiltrate neighboring tissues. In most cases, the tumor is confined to the musculature and the overlying aponeurosis or fascia. Occasional lesions may involve the periosteum and even lead to bone erosion, thereby confusing it with desmoplastic fibroma of the bone [15]. These tumors are distinct and separate from the broad spectrum of lesions categorized as variants of benign fibromatoses, such as Dupuytren's contracture, plantar fibromatosis,
Cytogenetics of desmoids
Although most desmoids appear normal on cytogenetic studies, trisomies for chromosomes 8 or 20 have been reported in approximately 20% of cases [16], [17], [18]. These are characteristically found in only about 10% to 30% of the desmoid tumor cells in any one patient and are most likely to be secondary mutations. Of interest, some reports suggest that desmoids associated with trisomy 8 are at increased risk of subsequent local recurrence [18], [19]. Desmoid tumors from FAP may occasionally
Differential diagnosis
Box 1 presents the common histologic differentials of desmoids with their characteristic findings [15].
Natural history
The clinical behavior of these tumors is unpredictable. Most lesions are likely to progress and may need treatment, but hematogenous or lymph node metastases have not been reported. Multicentric disease and recurrence (or reactivation) at sites other than the primary location have been reported [13]. Although mortality is rare in patients with extra-abdominal disease, it has been observed in some head and neck lesions [13]. Many lesions progress and some are refractory to multiple surgical
Imaging studies
Desmoid lesions usually present as a soft tissue mass that interrupts the adjacent intermuscular and soft tissue planes. These lesions can sometimes encroach on the adjacent bone and cause pressure erosions or superficial defects of the cortex. Sometimes a periosteal reaction consisting of “frond-like” spicules of bone may be found extending deep into the tumor [26].
MRI scans are helpful in the diagnosis and assessment of tumor extent before surgery. It is important to note that desmoid tumors
Clinical presentation
Extra-abdominal lesions are most common in patients between puberty and 40 years of age, with a peak incidence between the ages of 25 and 35 years [15]. Lesions are located in a variety of anatomic locations, with shoulder, chest wall, back, and thigh being the most frequent locations, in that order (Fig. 3).
Reitamo and colleagues [31] divided their series of 89 cases into four major age groups in which the sites of the tumor, the sex of the patient, or both were nonrandomly distributed (Box 2).
Management
Management of desmoid tumors should be a multidisciplinary approach. Management should be aimed at achieving local control without the sacrifice of function or cosmesis. Surgery with a wide margin of resection remained the primary treatment modality until recent years and offered the best chance of avoiding recurrence; however, the indications and results of adjuvant therapies including chemotherapy and combination therapy (surgery with radiation or chemotherapy) are evolving. It is important
Surgery
When medically and technically feasible, surgery has been the traditional first-line therapy. Even when feasible, the morbidity and functional impairment resulting from surgery should be weighed against the expected behavior of the tumor and the potential efficacy of other treatments (Fig. 4). Multiple studies have documented excellent local control, with recurrence rates of 70% to 80% with wide negative margins [32], [33]. Due to the tendency of these lesions to penetrate microscopically
Radiation therapy
External beam radiation therapy has mainly been employed (1) in patients with unresectable disease, (2) to avoid mutilating surgery, (3) for gross residual tumor, and (4) for positive or equivocal margins following surgery. There are several recent studies that continue to support the efficacy of radiation therapy as primary or adjuvant therapy with surgery. Outcomes of 65 patients treated at the University of Florida in Gainesville with radiation or surgery plus radiation suggest that
Chemotherapy and other pharmacotherapy for desmoid tumors
Cytotoxic and noncytotoxic chemotherapeutic agents have been employed as adjuvants for the treatment of desmoids. Frequently, intra-abdominal and mesenteric tumors and large-extremity tumors are good candidates for medical therapy because of their poor candidacy for surgical or radiation management. An excellent review of the various drug approaches to desmoid tumors has recently been published [41].
Weiss and Lackman [42] employed vinblastine and methotrexate in eight patients who were not
Novel approaches
In their study of nine patients with treatment-refractory disease who had exhausted surgical, radiation, and other medical therapy options, Mace and coworkers [47] were able to demonstrate that all lesions expressed platelet-derived growth factor receptors. Two of the patients with recurrent disease underwent a trial with the tyrosine kinase inhibitor imatinib mesylate and experienced a partial response, with improved quality of life at 9 and 11 months.
Expression of somatostatin receptor
Summary
Desmoids are a challenging group of lesions with variable biologic behavior and local morbidity but with no metastatic potential. Modern treatment involves a multidisciplinary and individualized approach based on the location, extent, and status of recurrence. Surgery continues to be a popular therapy for small resectable tumors. Radiation is also an effective alternative; however, its potential carcinogenic side effects must be weighed carefully in the context of young patients. Low-dose
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