Prognostic significance of a positive microscopic margin in high-risk extremity soft tissue sarcoma: implications for management.
A positive microscopic margin (PMM) is a significant prognostic variable and leads to local recurrence (LR) in high-grade soft tissue sarcoma (STS) patients. Its effect on the rate of distant metastasis (DM) and tumor mortality (TM) remains controversial.
One hundred sixty-eight primary, high-risk (high-grade, deep, > or = 5 cm) extremity STS patients were identified from our data base, of which 42 had a PMM. Limb-sparing surgery (LSS) was the primary surgical therapy in 144 patients; 24 received amputation (AMP). Statistical analysis was by log-rank test and Cox model. Significance was defined as a P value less than .05.
A PMM was a significant negative prognostic factor for both DM and TM (P = .002 and .002, respectively). However, those patients who received LSS with 28% PMMs showed no significant difference in the rate of DM or TM compared with patients who received AMP with only 8% PMMs (log-rank, P = .057 and .28, respectively). A PMM was significantly associated with > or = 1,000 mL blood loss and more than 3 hours of operating time (P < .006 and .001, respectively).
The strong statistical significance that relates a PMM to DM and TM in high-risk STS of the extremity is likely related to biologically aggressive tumors and LSS. Residual microscopic disease is not a guarantee of LR. The main problem in this group of patients is not LR, but DM and subsequent death. Therefore, to increase a disability with further surgery or amputate a patient's limb without clear evidence of LR in this group at high risk for distant recurrence is not recommended.