After a biopsy, lumpectomy, or mastectomy, a pathologist will check the boundaries of the tissue removed for any cancer cells, and will rate it clear/negative, positive, or close. Clear (also called Negative or Clean): No cancer cells are seen at the outer edge of the tissue that was removed (the tumor along with the rim of surrounding tissue). When margins are clear, usually no additional surgery is needed. Positive: Cancer cells come right out to the edge of the removed tissue. More surgery is usually needed to remove any remaining cancer cells. Close: Cancer cells are close to the edge of the tissue, but not right at the edge. More surgery may be needed.