Surgery is usually followed by radiotherapy
British scientists have developed a technique which could replace the need for six weeks or more of daily radiotherapy.
This is followed by temporary insertion of a metal sphere into the cavity to provide 25 minutes of radiation therapy for the breast tissue from the inside out. The sphere is then removed and the wound stitched up.
So far the technique has been successfully piloted in 30 women.
Researcher Dr Jayaant Vaidya said: "Approximately three-quarters of women with breast cancer are candidates for lumpectomy, rather than mastectomy, which is total removal of the breast.
"But because lumpectomy typically involves daily radiation treatment for an extended period of time, and mastectomy typically does not require radiation therapy, women sometimes choose mastectomy.
"If this new technique is proved effective, it should make lumpectomy available to many more patients.
"Early tests are promising."
Jeffrey Tobias, a tumour specialist at the school, said: "We believe this is going to work. Most cancer recurrences occur immediately adjacent to the tumour - an area which receives radiation with this method."
Electron generator
The metal ball which is lowered into the area where the tumour was removed is charged by an electron generator.
It then emits a dose of ionising radiation lasting from 21 to 28 minutes.
The report said the technique is not sufficient for a form of breast cancer called lobular carcinoma, which accounts for up to 15% of all breast cancers.
Dr Vaidya said victims of such cancer still need an extended period of radiation but the radiating sphere can be used initially.
Dr Lesley Walker, of the Cancer Research Campaign, told BBC News Online: "The whole experience of diagnosis and surgery for breast cancer is traumatic enough without the need for a follow-on six week course of radiotherapy.
"If this treatment really holds up it will be a positive step forward."
The technique was outlined in a report delivered at the annual meeting of the Radiological Society of North America on Monday.