Buttock soft tissue sarcoma: clinical features, treatment, and prognosis.

Background: Primary buttock soft tissue sarcomas in adults are common entities that have been infrequently reported (three clinical series and isolated case reports). We present our experience of buttock sarcomas to better characterize and define the natural history of this condition.
Methods: Buttock tumors occurring in adults (>16 years) between January 1990 and January 2002 were identified from the Royal Marsden Hospital's Sarcoma Unit prospective database.
Results: Seventy-three buttock sarcomas were evaluated and treated at the Royal Marsden Hospital during this period. Liposarcoma (n = 19), leiomyosarcoma (n = 13), and synovial sarcoma (n = 9) were the most frequent histological types. There were 8 T1 and 61 T2 tumors, and size was not available in 4 patients. Most tumors (n = 64) were located deep to the deep fascia. There were 15 grade 1, 20 grade 2, and 37 grade 3 tumors, and grade was not available in 1 patient. There were 29 tumors contained within the gluteus maximus. Wide excision was performed in 50 patients. Local recurrence and distant metastasis occurred in 15 and 35 patients with a median time of 18 and 8 months, respectively. The rate of local recurrence at 2 years was 20.9% (SE, 6.8%). The 2-year overall and disease-free survival rates were 64.1% (SE, 6.7%) and 48.5% (SE, 6.4%), respectively.
Conclusions: Buttock sarcomas present special surgical difficulties because of proximity of the sciatic nerve and the ability of tumors at this site to extend into the pelvis and perineum. Size and grade of the tumor were independent predictors for disease-free and overall survival.