Clinical investigation: sarcoma
Use of intraoperative electron beam radiotherapy in the management of retroperitoneal soft tissue sarcomas

Presented at the 38th Annual Meeting of the American Society for Therapeutic Radiology and Oncology, Los Angeles, October 27–30, 1996.
https://doi.org/10.1016/S0360-3016(01)02595-0Get rights and content

Abstract

Purpose: To evaluate the disease control, survival results, and tolerance of intraoperative electron beam radiotherapy (IOERT) as a component of treatment for retroperitoneal soft tissue sarcomas.

Methods and Materials: Between March 1981 and September 1995, 87 patients with primary (n = 43) or recurrent (n = 44) retroperitoneal or intrapelvic sarcomas received IOERT as a component of treatment at the Mayo Clinic. The tumors were high grade in 54 patients (62%) and low grade in 33 (38%). The median tumor size was 10 cm (range 2–36). All patients underwent maximal surgical resection with IOERT; in 72 patients, only microscopic or no residual tumor remained. The IOERT doses ranged from 8.75 to 30 Gy (median 15). All primary tumors received external beam irradiation (EBRT) with a median dose of 48.6 Gy. Thirty-four of the 44 recurrent tumors received EBRT to a median dose of 45 Gy. All patients were followed prospectively for outcome and toxicity evaluation.

Results: The median follow-up, based on 46 patients (53%) currently alive, was 3.5 years. The overall estimated 5-year survival was 47%. For patients with tumors ≥10 cm, the 5-year overall survival was significantly poorer (28%) than for those with smaller lesions (60%) (p = 0.01). Neither primary vs. recurrent status nor tumor grade had a significant impact on survival. Patients with gross residual tumor had a marginally significantly poorer survival compared with patients with microscopic or no residual tumor, with a 5-year survival rate of 37% and 52%, respectively (p = 0.08). A total of 49 patients (56%) experienced failure, including 20 local recurrences (23%). The median time to failure was 2.3 years. Four recurrences were within the IOERT field, 3 within the IOERT and EBRT field, and 13 within the EBRT field alone. The 3- and 5-year estimated local control rate was 77% and 59%, respectively. Local control was marginally significantly affected by the amount of residual tumor, with a 5-year local control rate of 41% for those with gross residual tumor, 60% for those with microscopic residual tumor, and 100% for those with no residual tumor (p = 0.09). Gastrointestinal complications were recorded in 12 incidences (Grade 3 or higher toxicity). These complications were believed to be secondary to surgery and/or EBRT in 10 of the 12 cases. Seven patients had fistula formation, and 3 experienced severe proctitis. Grade 3 peripheral neurologic toxicities occurred in 9 patients (10%), but none had pain as a component of their neuropathy.

Conclusion: Retroperitoneal soft tissue sarcomas can be treated with an aggressive combined approach of EBRT, surgery, and IOERT, with acceptable toxicity. Local control in primary disease appears to be improved in this retrospective series with this approach. Distant disease control and options for recurrent disease needs further definition.

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

References (18)

There are more references available in the full text version of this article.

Cited by (0)

View full text