Taking a margin
The margin is the border between cancerous and healthy tissue. It is an area of tissue close to the tumour, which the surgeon judges to be healthy.
Taking a margin reduces the risk of leaving any breast cancer cells behind
that could grow again.
If any cancer cells, or cells that might develop into cancer, are found at the edge of the removed tissue then you may need further surgery. This may involve either more breast tissue being removed or a mastectomy, where the whole breast is removed.
Also within "Treatment"

