The prognostic factors at the time of the first recurrence of retroperitoneal liposarcoma

Background This study aimed to identify prognostic factors at the time of the first recurrence of retroperitoneal liposarcoma (LPS). Methods The medical records of 150 patients who underwent tumor resection for primary retroperitoneal LPS at our institute were reviewed. Among 94 patients who experienced tumor recurrence, including both local and distal recurrence, the prognostic factors for recurrent LPS and the treatment patterns were retrospectively analyzed. Results Tumor resection, radiation therapy, and chemotherapy were performed in 41, 12, and 23 patients, respectively, whereas active surveillance (AS) continued in 12 patients, and 6 patients received best supportive care. In the univariate analysis, well-differentiated LPS as the primary tumor differentiation was a predictor of better overall survival compared with dedifferentiated LPS (p = 0.004). In the multivariate analysis, tumor multifocality and treatment choice other than AS and resection were poor prognostic factors (p = 0.005 and p = 0.003, respectively), while primary tumor differentiation showed a marginal effect (p = 0.069). A discrepancy between initial and recurrent tumor differentiation was observed in 12 of 41 (29.2%) patients who underwent surgery for recurrent LPS. Recurrence-free survival from the first surgery was a significant predictor of recurrent tumor differentiation (p = 0.026). Conclusions Tumor multifocality and treatment choice were prognostic factors for the first recurrence of retroperitoneal LPS. A change in tumor differentiation from the primary tumor to recurrence occurred frequently, and recurrence-free survival from the first surgery may be useful to predict this change.