2002 CTOS Annual Meeting Oral Presentations — Radiation Oncology

HIGHER POSTOPERATIVE RADIATION DOSE IMPROVES THE LOCAL CONTROL RATE FOR PATIENTS WITH POSITIVE SURGICAL MARGINS AND LOCALLY RECURRENT SOFT TISSUE SARCOMA
[Abstract ID: 33]

Category: Radiation Oncology

Presentation: Oral

Authors: Matthew T Ballo¹, Gunar K Zagars¹, Shreyaskumar R Patel¹, Peter WT Pisters¹

Author Institutions: ¹UT MD Anderson Cancer Center, United States

Presenter: Matthew T Ballo
Email: mballo@mdanderson.org

Correspondent: Matthew T Ballo
mballo@mdanderson.org
Houston Texas United States 77030
Ph: 713-792-3400
Fax: 713-794-5573

Objectives: To evaluate the relationship between postoperative external beam radiation dose and local control for patients with risk factors for local recurrence after surgery and radiation.

Methods: From 1961 to 1999, 804 patients with non-metastatic soft tissue sarcoma were treated with gross total surgical resection and post-operative radiation, with or without adjuvant chemotherapy. Histological sub-type was as follows: MFH, 265 patients; liposarcoma, 97; synovial sarcoma, 91; unclassified, 90; neurogenic sarcoma, 58; Rhabdomyosarcoma, 39; other, 164. Surgical resection margins were positive or uncertain in 377 patients. One hundred and forty eight patients (18%) presented with locally recurrent disease after previous surgical resection. Histological grade was low/intermediate in 234 patients and high in the remaining 570 patients. Median tumor size was 5cm (range 0.5-36cm). Radiation was delivered to a median dose of 61Gy (range 36-75). Only 11 patients received doses <50Gy. Adjuvant systemic therapy was given to 215 patients.

Results: At a median follow-up of 12 years, 322 patients (40%) developed disease relapse at any site. The 10-year actuarial overall and disease-free survival rates were 61% and 58%, respectively. The 10-year actuarial local, nodal and distant control rates were 79%, 96%, and 70%, respectively. Multivariate analysis confirmed an independent association between positive surgical resection margins (p<0.001), age >47 years (p=0.002), high histological grade (p=0.006), size >5cm (p=0.01), locally recurrent disease (p<0.001), postoperative radiation dose <64Gy (p<0.001) and an inferior 10-year local control rate. In three of these high-risk sub-groups higher radiation dose postoperatively improved the 10-year local control rate. For patients with positive surgical resection margins radiation dose ›64Gy resulted in a 10-year local control rate of 75% compared to 55% for lesser doses (p<0.001). For patients presenting with locally recurrent disease after previous surgical treatment radiation doses ›64Gy resulted in a 10-year local control rate of 76% compared to 59% for lesser doses (p=0.05). For patients with high grade disease the same doses resulted in 10-year local control rates of 79% as compared to 74%, however this difference was of only borderline significance (p=0.06).

Conclusions: This radiation dose-response analysis suggests that the adverse prognostic significance of positive surgical resection margins and locally recurrent disease after surgical resection may be partially overcome with postoperative radiation dose in excess of 64Gy.