Rein vision

Think of "margins" as a halo around the tumor. When they cut the tumor out, they look at the edges of the tissue sample. The pathologist is looking for no cancer at the edge of the removed sample. If the margins are "negative" it means they do not see cancer at the edge. Usually they will give an actual distance (i.e. 5 mm margin means there are 5 mm of healthy, non-cancerous cells between the edge of the removed tissue and any cancerous cells). If the margins are "positive" it means that there is cancer all the way to the edge of the sample and that there is likely a little bit left inside of you. Surgeons are very different as to how much of of a negative margin they want. Some want 5 mm, some want 2 mm, and some want something different.