National Cancer Centre - Cancer Update

The role of radiotherapy in treating invasive breast cancer involves killing microscopic cancer cells after surgery and chemotherapy, killing gross tumours and palliating bleeding from tumours, bone pain or brain metastases.

An analogy
An analogy in the use of radiation is to liken cancer to a tree. The surgeon chops it down. If the tree is huge, its roots may grow again. Radiation is used to kill these roots, followed by chemotherapy to destroy seeds that may have spread. If the tree is small, it may not leave behind roots and is less likely to have seeds, so radiation and chemotherapy is not needed. Radiation is used only after mastectomy and axillary clearance, when tumours are over 5 cm and have nodal involvement.

Radiotherapy uses radiation to get rid of tumours, while sparing normal tissues. Radiation treatment spares the organ, i.e. tumour is stamped out while sparing normal tissues and the organ. Patients with small tumour will benefit from this treatment which also serves to preserve the breast. (Read the article on Breast conservation and reconstruction).

When is radiotherapy used?
For tiny tumours, avoid removing the whole breast. Instead, radiotherapy is used to eliminate remaining tumours (after lumpectomy and axillary clearance). The treatment usually lasts six weeks. For some patients, the breast is treated by brachytherapy. For large ulcerating or bleeding tumours, radiation is an effective means of controlling the tumour. For bone metastases, radiation can relieve pain. A short treatment course to control pain may last one day to two weeks. For brain metastases, radiotherapy is effective in relieving patient's neurological symptoms. Radiotherapy is given by conventional treatment fractionation over two weeks. For few and small tumours, radiotherapy is given as a single fraction using radiosurgery, delivered with the Gamma Knife or with the use of a linac-based radiosurgical equipment. For hormone-sensitive tumours, restricting estrogen supply is one way to contain tumours. Alternatively, the ovaries can be radiated and may cause an artificial menopause. The treatment lasts about five days. For tumours confined to breast ducts (also called intraductal cancers), the patient is first treated by a wide excision followed by six weeks of radiation.
External beam scan to treat breast cancer	Breast treated by brachytheraphy	Dr Chua Eu Tiong Deputy Head Therapeutic Radiology