Why Do Patients with Low-Grade Soft Tissue Sarcoma Die?

Introduction: The patterns of failure and mechanisms of sarcoma-specific death are poorly characterized among the minority of patients with low-grade soft tissue sarcoma (STS) who succumb to disease. Methods: Between 1982 and 2006, 2,041 patients aged >= 16 years with low-grade STS of all sites were treated with curative intent and prospectively followed at a single institution. Results: Among this cohort, 181 (9%) died from disease (DOD). Overall, 105 patients (58%) died from locally recurrent disease (DOLR), and 59 (32%) died from distant disease (DODR). In 17 patients (9%), the mechanism of sarcoma-related death could not be verified. DOD occurred at a median of 62 months, while median disease-specific survival for the entire cohort was not reached. Median follow-up was 66 months (range 2-431 months). On multivariate analysis, DOD was associated with site, size, and less than R0 resection. For DOLR, site, size, positive margins, liposarcoma histology, and local recurrence (by definition) were significant factors. For DODR, site, histology, and positive margins were not significant factors, while size and local recurrence were. Of DOLR, 80% were retroperitoneal, 68% were liposarcoma, and only 2% were extremity. Conversely, of DODR, extremity (47%) and trunk (18%) were the most common sites, but histology was more variable [liposarcoma 35%, malignant fibrous histiocytoma (MFH) 20%, fibrosarcoma 12%, extraskeletal myxoid chondrosarcoma 10%]. High-grade recurrence rates were comparable between DOLR (27%) and DODR (25%). Conclusion: Among patients with low-grade STS, DOD occurs in approximately 9% of patients. Nonextremity site, larger size, and less than R0 resection are the most important risk factors for DOD, and distinct patterns of recurrence and death are predicted by primary tumor site.