Posters— Radiation Oncology

IS ADJUVANT RADIATION THERAPY (RT) INDICATED AFTER OPTIMAL RESECTION FOR SOFT TISSUE SARCOMA (STS) OF THE EXTREMITIES?

A. Le Cesne, K. Khanfir, P. Terrier, L. Alzieu, S. Bonvalot, D. Vanel, and C Le Péchoux. Soft Tissue Sarcoma Unity, Institut Gustave Roussy, Villejuif 94805. France

The impact of adjuvant RT on both local control and distant relapse is not clearly established after wide excision of extremity STS.

Purpose: we performed a retrospective analysis on behavior of patients (pts) who underwent a large resection in our institution (first or second resection in case of incomplete surgery) and received or not adjuvant RT. All histological specimen were carefully analyzed and only pts with free tumoral margins (ftm) were retained for analysis. Histopathological classification was as following : minimal RO (mRO) resection (ftm<10 mm) and optimal RO (oRO) resection (ftm >= 10 mm).

Patients: from 1975 to 1996, 133 pts with a median age of 44 years (yrs) were operated at IGR. The median tumor size was 6 cm (range 1 to 18 cm). Ninety-three pts (70%) primary resected in other centers, were reoperated and residual tumor cells were found in 54% of pts. Sixty-nine pts (17 oRO and 52 mRO) received adjuvant RT and 64 pts did not (54 oRO and 10 mRO). Characteristics of pts (age, tumor size, grade, adjuvant chemotherapy) were similar in both RT and no-RT groups.

Results: Median follow-up time was 10 years (3 to 25). Thirty-three pts had a local relapse: I I in the RT group and 22 pts in the control group (p=0.01). Grade and ftm. are correlated to overall survival and adjuvant RT is correlated to relapse free survival in univariate analysis. A positive impact of RT on local control was only seen in pts with a mRO resection (p= 0.005) and in pts with residual tumor cells after reexcision (p=0.001). RT has no influence on 5 and 10 yr-overall survival.

Conclusion: optimal resection seems to be the best predictive parameter for a favorable outcome in term of local control in localized STS. Adjuvant RT is indicated in mRO resections and in case of residual tumor cells after definitive surgery, but its r6le after oRO resection has to be validated by a prospective randomized trial