OUTCOME AND PROGNOSIS IN RETROPERITONEAL SOFT-TISSUE SARCOMA

Purpose: To retrospectively evaluate the outcome of treatment and iden tify factors prognostic for survival and locoregional and distant dise ase control for patients with retroperitoneal soft tissue sarcoma. Met hods and Materials: The records of 104 patients with retroperitoneal s oft tissue sarcoma (RSTS) managed with surgery and irradiation at Prin cess Margaret Hospital between 1975 and 1988 were retrospectively revi ewed. Univariate log-rank analysis was used to evaluate potential prog nostic factors. Results: Presentation was new primary disease, 74; pri mary recurrence, 20; metastases, 10. Pathology was liposarcoma for 42, leiomyosarcoma for 22, malignant fibrous histiocytoma for 19, and 21 with other histologies. Grade was low for 36, high for 35, and 33 were not graded. Median tumor size was 17 cm. Grossly complete surgical ex cision was achieved for 45 (43%), of whom 6 (6%) also had clear surgic al margins. Adjuvant postoperative irradiation was administered to 36 patients to a median dose of 40 Gy/20 fractions/4 weeks and 16 receive d adjuvant chemotherapy. Nine patients received no adjuvant postoperat ive radiotherapy. Gross residual tumor was present postoperatively in 57 patients. The overall 5- acid 10-year survival rates were 36% and 1 4%, respectively. The locoregional relapse free rate (RFR) was 28% at 5 years and 9% at 10 years, and the distant RFR was 76% at 5 years and 60% at 10 years. For the 45 patients treated with complete excision, survival was 55% and 22% at 5 and 10 years, and locoregional RFR was 5 0% and 18% at 5 and 10 years. Univariate analysis demonstrated that co mplete surgical removal was the only factor significant for improved s urvival, locoregional RFR, and distant RFR. Liposarcoma histology pred icted for improved survival (p = 0.02), and leiomyosarcoma histology f or a lower distant RFR, compared to other histologies (p = 0.003). Pat ients under 62 years had an improved survival (p = 0.002) and local RF R (p = 0.02), and patients presenting with recurrent disease had impro ved survival (p = 0.03). Sex, tumor size, or grade, or the use of adju vant chemotherapy were not predictive for any of the endpoints tested. Those who received adjuvant irradiation following gross surgical clea rance experienced a prolonged median locoregional RFR over those who d id not, and this approached statistical significance for those receivi ng radiation doses > 35 Gy. (103 months vs. 30 months, p = 0.06). Stat istical significance was reached (p = 0.02) if only the infield RFR wa s considered. Conclusions: This study demonstrates that failure to ach ieve local control is the primary cause of treatment failure for patie nts with RSTS, and that postoperative irradiation in doses > 35 Gy aft er complete surgery delayed, but did not prevent local recurrence. Imp rovements in outcome for patients with RSTS will require alternate tre atment strategies, and preoperative irradiation with an aggressive sur gical attempt at complete excision is currently under investigation.