International Journal of Radiation Oncology*Biology*Physics
Clinical investigation: sarcomaUse of intraoperative electron beam radiotherapy in the management of retroperitoneal soft tissue sarcomas
Introduction
Retroperitoneal and intrapelvic soft tissue sarcomas are challenging tumors for today’s oncologist. Frequently, these tumors are large and may involve vital structures within the abdominal or pelvic cavity at the time of diagnosis. Complete resection may not be feasible in approximately one half of patients at presentation, and, when gross total resection is possible, the margins are typically narrow because of the normal tissue limitations 1, 2, 3, 4, 5. Failures occur predominately at the local site but also distantly. Surgery remains the mainstay in the management of this malignancy but it fails to control local disease in 70–90% of patients 1, 2, 4. Even patients surviving >5 years have a significant local failure rate of 58%, as reported by a recent study from Memorial Sloan-Kettering Cancer Center (3).
Radiation has been used in a variety of manners with varied success 6, 7, 8, 9, 10, 11, 12. External beam irradiation (EBRT) alone is limited by the dose tolerance of multiple structures in this region, and the doses typically used for extremity soft tissue sarcomas exceed the normal tissue tolerances of several organs. Intraoperative radiotherapy with electrons (IOERT) in combination with EBRT was found to improve local control statistically compared with EBRT alone in one randomized study (8). That study also showed a decreased rate of acute and chronic gastrointestinal complications with the combination of IOERT and EBRT. Willett et al. (11) reported on a small series of patients treated with IOERT for primary and recurrent soft tissue sarcomas with good local control in patients with microscopic residual tumor at the time of resection. The present report is a retrospective review of a large, single-institution experience with IOERT in the management of retroperitoneal and intrapelvic soft tissue malignancies and the toxicities associated with their treatment.
Section snippets
Methods and materials
Between March 1981 and September 1995, 87 patients with retroperitoneal or intrapelvic soft tissue sarcomas received IOERT as a component of therapy at our institution. Of the 87 patients, 43 had primary lesions and 44 recurrent soft tissue sarcomas. No patient had evidence of metastatic disease at the onset of treatment. The characteristics of these patients and their sarcomas are outlined in Table 1. Three patients were children. A variety of histologic subtypes were treated, but
Survival
Surviving patients have been followed for a median of 3.5 years (range 0.5–11.5). At last follow-up, 46 (53%) of the 87 assessable patients were alive. The 2- and 5-year overall survival rate was 83% and 48%, respectively. At 2 and 5 years, the disease-free survival rate for all patients was 55% and 29%, respectively. Thirty-three patients died of their disease, 7 of other causes, and 1 of unknown causes. The 5-year survival rate was marginally worse (p = 0.08) in patients with gross residual
Discussion
Retroperitoneal soft tissue sarcomas account for about 14% of all soft tissue sarcomas (14). The completeness of the surgical resection remains essential to the favorable outcome of patients with this disease (3). The Memorial Sloan-Kettering Cancer Center reported a 5-year survival rate of 40% in patients having a complete excision compared with 3% in patients with biopsy or partial resection (1). In the series by van Doorn et al. (10), the 5-year survival rate after complete resection was
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