Retroperitoneal Sarcomas

Retroperitoneal sarcomas are rare, accounting for approximately 10–15% of all soft-tissue sarcomas with an estimated 1,500 cases occurring annually in USA [1, 2]. The most common histologic subtypes include liposarcoma, leiomyosarcoma, and malignant fibrohistiocytoma [3]. Approximately 33–50% of retroperitoneal sarcomas are low grade, in contrast to 19–26% of extremity and truncal sarcomas [4, 5], possibly explaining the lower incidence or delayed appearance of metastatic disease in these patients. In view of the expansile and invasive growth of retroperitoneal sarcomas, as well as the potential for asymptomatic tumor growth within the abdomen and retroperitoneum, patients frequently present with advanced tumors with local organ invasion. Approximately 71–94% of patients present with tumors >10 cm in diameter [2, 5]. In contemporary series, complete gross resection rates of retroperitoneal sarcomas range from 64 to 95% [6]. Even in resectable cases, the extent of disease frequently makes complete resection difficult, with microscopic or gross disease left intact in a high percentage of patients. Given these factors, the incidence of local recurrence following resection is high. Collective reviews of surgical series of retroperitoneal sarcomas have shown that local recurrence (as opposed to distant recurrence in extremity sarcomas) is the primary mode of failure, occurring in 41–82% of patients following gross total resection [7, 8]. Additionally, surgery-alone series describing long-term follow-up of patients undergoing gross total resection have demonstrated that relapses frequently occur many years following resection, with 10-year local recurrence rates of 82–91% [1, 9]. Further emphasizing this point, one series reported that in resected patients who are disease free at ≥5 years from initial surgery, 40% will recur by 10 years [10].