Proffered Papers— Radiation Oncology

COMPLETE RESECTION AND INTRA-OPERATIVE RADIATION THERAPY IMPROVE OUTCOME OF RETROPERITONEAL SARCOMAS

Pierie JPEN, Betensky RA, Choudry U, Willett CG, Souba WW, Ott MJ. (Massachusetts General Hospital Cancer Center, Boston MA 02114)

Objective: The assessment of long-term outcomes of patients with retroperitoneal sarcomas (RS) undergoing resection and External Beam Radiation Therapy (EBRT) with or without Intra-Operative Electron Beam Radiation Therapy (IOERT). Summary and background data: Despite improved imaging, surgical techniques, and technical innovations in radiation therapy, the survival of patients with RS is still poor. Survival might be enhanced with improved local control, when IOERT is added to the treatment regimen.

Methods: One-hundred and three consecutive patients treated for primary RS were studied. The median follow-up was 27 months (range 1-193). Demographic features, clinical presentation, stage and histology of the tumor, the type of surgical treatment, and the addition of EBRT and IOERT were analyzed to determine their impact on survival and recurrence.

Results: The mean age at presentation was 55 ± 17 years (range 10-93), with a slight female preponderance (56:47). Sixty-six per cent of the patients presented with of pain or discomfort, 30% with a palpable mass, 23% with distant disease and 5% with lymph node metastases. The mean tumor size was 15 ± 6 cm (range 3-34). The most common histologic type was leiomyosarcoma (27%) with predominately high-grade tumors (86%). Complete gross resection of the tumor was possible in 61% of patients and this increased survival versus both debulking (hazard ratio [HR] = 0.30, p = 0.0005) and biopsy (HR = 0.22, p < 0.0001). The five and ten year survival rates were 62% and 52% for those with complete resection versus 29% and 20% after incomplete resection.

In all 103 patients, IOERT plus EBRT enhanced survival as compared with EBRT alone (HR = 0.40, p = 0.058). Five and ten year survival rates were 70% after the use of IOERT. In a multivariate model including all 103 patients, male gender, increasing size of the tumor, a more advanced stage of the tumor, the resection of more than 1 organ, a histology of malignant Schwannoma, incomplete resection of the tumor and the absence of IOERT, were associated with a decreased survival.

Among the 62 patients undergoing a complete resection, there was a trend for IOERT to further augment survival as compared with EBRT alone (HR = 0.38, p = 0.13), leading to five and ten year survival rates of 77%. IOERT increase the time to both local and distant recurrence as compared with EBRT alone (HR = 0.27, p = 0.036) in this group.

Conclusions: Complete gross resection remains the most effective treatment for retroperitoneal sarcomas. The addition of IOERT to EBRT is more effective than EBRT alone in increasing survival and decreasing both local and distant recurrence after complete tumor resection.