In the past it was common for surgeons to try and take away as many lymph nodes as possible from under the arm. This surgery was then followed by radiotherapy to the remainder of the breast (or the wall of the chest, if a mastectomy had been done). Radiotherapy was also given to the tissues under the arm (the axilla). This very often led to swelling of the arm (lymphoedema).

It is now recognised that if the surgeon takes away most of the lymph glands from under the arm, radiotherapy to that area is not necessary. National guidelines from the Royal College of Radiologists say that if more than 10 lymph glands have been removed from under the arm then radiotherapy to the axilla is not needed, even if some of the glands contained seedlings of tumour. The only exception to this is if there are signs that there was tumour in the glands which has actually broken through the capsule to the lymph nodes and started to spread into the surrounding fatty tissues, in this case radiotherapy is still recommended - but this is very uncommon.

If cancer cells are found in some of the removed glands, treatment with hormonal therapy or chemotherapy would usually be recommended.

After an axillary clearance, there is still a risk that some swelling of the arm might develop but the chances of this happening is much less than in the past when both surgery and radiotherapy were used. If swelling occurs this can be managed by staff who are specialists in lymphoedema treatment.