The surgeon will aim to obtain clear margins. This means that a border of healthy tissue, with no cancer cells, should have been taken away from around the tumour. Specimens will be examined under the microscope to make sure that this has been done. It is important because the clear margin makes it much less likely that any cancer cells are left behind.

Your surgeon will usually also remove some of the lymph nodes (lymph glands) that are nearest to your tumour, because this is a common place for cancer cells to spread to. A doctor who specialises in diagnosing disease by examining tissues under a microscope (a pathologist) will judge whether the lymph nodes contain cancer cells. If they do, there may be an increased risk of the cancer coming back in the future, and you may need to have treatment such as radiotherapy, chemotherapy or hormonal therapy after your operation.