The description of surgical margins requires an understanding of the local behaviour of sarcomas. Classically, sarcomas grow centrifugally, and around the central tumour is a “reactive zone” comprising compressed normal tissues, inflammatory cells and small numbers of tumour cells. Tumours also tend to stay within osteofascial anatomical compartments. These concepts were popularised by Enneking, in the era before the widepsread availability of cross-sectional imaging.
The text-book answer is that surgical margins are described as follows:
- Intralesional – when the resection passes through tumour
- Marginal – when the resection passes through the reactive zone
- Wide – when the resection passes through normal tissue
- Radical – when the whole of the involved compartment is removed.
However, given that the majority of tumours are close to critical neurovascular structures for at least part of their circumference, most resections are technically marginal. A more helpful description is often whether or not the margin is microscopically positive (tumour at or within 1mm of the resection margin) or microscopically negative.
The surgical margin achieved is the strongest predictor of the risk of local recurrence in several large series.