Primary malignant retroperitoneal tumors: analysis of a single institutional experience.

AIMS: In order to achieve complete resection in the surgical management of retroperitoneal tumors, it is crucial to know the tumor's anatomical location relative to neighboring organs. METHODS: Forty-nine patients with primary malignant retroperitoneal tumors were divided by tumor location into two groups upper abdomen (group 1) or lower abdomen (group 2)], and clinicopathological features, tumor recurrence, and patient survival were assessed. RESULTS: No significant differences in preoperative clinical characteristics existed between two groups, and liposarcoma was the most frequently observed tumor type. The difference in the rates of complete resection between the two groups was not statistically significant (75.9% for group 1 and 85% for group 2). En-bloc combined resection was performed in 52% and 30% of patients in groups 1 and 2, respectively. The local recurrence rate in group 2 (31.3%) was higher than that in group 1 (9.5%), despite the fact that the differences in rates of complete resection and distant recurrence rates (14.3% in group 1 and 12.5% in group 2) between the two groups were not statistically significant. The overall 5-year survival rates were 67.9% for group 1 and 43.2% for group 2 (p=0.038). The 5-year survival rate of patients with tumors smaller than 10 cm was 78.4%, while that of patients with tumors larger than 10 cm was 38.1% (p=0.017). The 5-year survival rate after complete excision was 61%, whereas that after incomplete resection or biopsy only was 40.0% (p<0.0001). CONCLUSIONS: An upper abdominal tumor location is a positive prognostic factor even if small tumor size (<10 cm) and complete resection of the tumor are still more important factors to improve outcome in patients with malignant primary retroperitoneal tumors. Because complete resection was shown to be the most important prognostic factor, an aggressive and careful surgical approach is recommended for the treatment of such tumors.