The Study: A new large retrospective institutional series of >2000 sarcoma resections in JCO looks at the effects of different margin classifications on local recurrence risk. Most tumors were high grade and deep, and about 50% of patients received preoperative radiation. The authors introduce the “R+1mm” (tumor within 1mm of the margin) class to the standard R system. This reduced the rate of negative-margin (R0) resection from 86% to 66%, but patients with R+1mm resections had essentially the same local recurrence (LR) risk as R0 ones (~10% at 10 years). More interesting was the use of context margin classification. A planned positive margin at a critical structure had the same LR (again ~10%) as a negative margin. Unplanned positive margins, though, had a 35% risk of LR.
Bottom Line: Sarcoma as close as 1mm from the surgical margin and even present at a planned margin doesn’t seem to significantly increase the risk of LR. In other words, margin status isn't black and white.