Management of extremity soft tissue sarcomas with limb-sparing surgery and postoperative irradiation: do total dose, overall treatment time, and the surgery-radiotherapy interval impact on local control?

PURPOSE

To evaluate potential prognostic factors in the treatment of extremity soft tissue sarcomas that may influence local control, distant metastases, and overall survival.

METHODS AND MATERIALS

Sixty-seven patients with extremity soft tissue sarcomas were treated with curative intent by limb-sparing surgery and postoperative radiation therapy at the Fox Chase Cancer Center or the Hospital of the University of Pennsylvania, between October 1970 and March 1991. Follow-up ranged from 4-218 months. The median external beam dose was 60.4 Gy. In 13 patients, interstitial brachytherapy was used as a component of treatment.

RESULTS

The 5-year local control rate for all patients was 87%. The 5-year local control rate for patients who received < or = 62.5 Gy was 78% compared to 95% for patients who received > 62.5 Gy had larger tumors (p = 0.008) and a higher percentage of Grade 3 tumors and positive margins than patients who received < or = 62.5 Gy. The 5-year local control rate for patients with negative or close margins was 100% vs. 56% in patients with positive margins (p = 0.002). Cox proportional hazards regression analysis was performed using the following variables as covariates: tumor dose, overall treatment time, interval from surgery to initiation of radiation therapy, margin status, grade, and tumor size. Total dose (p = 0.04) and margin status (p = 0.02) were found to significantly influence local control. Only tumor size significantly influenced distant metastasis (p = 0.01) or survival (p = 0.03).

CONCLUSION

Postoperative radiation therapy doses > 62.5 Gy were noted to significantly improve local control in patients with extremity soft tissue sarcomas. This is the first analysis in the literature to demonstrate the independent influence of total dose on local control of extremity soft tissue sarcomas treated with adjuvant postoperative irradiation.