Aims: To report the effect on outcome of selection in patients receiving intra-operative electron beam radiation (IOERT) and external beam radiation therapy (EBRT). Methods: One hundred and three patients treated for primary RS were studied. Median follow-up was 27 months. Clinical presentation, tumor characteristics, and treatment methods were analyzed to determine impact on survival and recurrence and if selection was occurring. Results: Mean age was 55 ± 17 years. Mean tumor size was 15 ± 6 cm and 88 were high-grade. Complete gross tumor resection (CR) occurred in 62 patients and improved survival vs. both debulking (p = 0.0005) and biopsy (p < 0.0001). The 5- and 10-year survival rates were 62% and 52% for those with CR vs. 29% and 20% after incomplete resection. Among the 62 CR patients, there was selection to receive additional EBRT ± IOERT in patients with high-grade tumors (p = 0.005) and/or microscopically positive margins (p = 0.011). In these high-risk patients there was a trend for IOERT to further augment survival vs. EBRT alone and to increase the time to both local and distant recurrences (p = 0.036). Conclusions: Complete gross resection is the primary form of curative treatment for retroperitoneal sarcomas. Selection led to patients with high-risk tumors receiving additional radiation therapy. There appears to be a beneficial effect of IOERT plus EBRT in these high-risk patients after complete tumor resection.
- Intra-operative radiation therapy