Long-term outcomes for desmoid tumors treated with radiation therapy.

PURPOSE: To evaluate long-term outcomes in patients with desmoid fibromatosis treated with radiation therapy (RT), with or without surgery. METHODS AND MATERIALS: Between 1965 and 2005, 115 patients with desmoid tumors were treated with RT at our institution. The median age was 29 years (range, 8-73 years). Of the patients, 41 (36%) received RT alone (median dose, 56 Gy) for gross disease, and 74 (64%) received combined-modality treatment (CMT) consisting of a combination of surgery and RT (median dose, 50.4 Gy).
RESULTS: Median follow-up was 10.1 years. Local control (LC) rates at 5 and 10 years were 75% and 74%, respectively. On univariate analysis, LC was significantly influenced by tumor size (< or =5 cm vs. 5-10 cm vs. >10 cm) (p = 0.02) and age (< or = 30 vs. >30 years) (p = 0.02). There was no significant difference in LC for patients treated with RT alone for gross disease vs. CMT. For patients treated with CMT, only tumor size significantly influenced LC (p = 0.02). Patients with positive margins after surgery did not have poorer LC than those with negative margins (p = 0.38). Radiation-related complications occurred in 20 (17%) of patients and were associated with dose >56 Gy (p = 0.001), age < or =30 years (p = 0.009), and receipt of RT alone vs. CMT (p = 0.01).
CONCLUSIONS: Desmoid tumors are effectively controlled with RT administered either as an adjuvant to surgery when resection margins are positive or alone for gross disease when surgical resection is not feasible. Doses >56 Gy may not be necessary to control gross disease and are associated with high rates of radiation-related complications.