The experimental treatment could make lumpectomy - a breast-saving type of cancer surgery in which only the lump is removed - available to many more women.
The technique, called intra-operative radiotherapy, uses a miniature radiation probe right after a lumpectomy. The probe is inserted inside the cavity created by the removal of the tumor, and radiation equivalent to six weeks of doses is emitted for about 25 minutes.
"Approximately three-quarters of women with breast cancer are candidates for lumpectomy, rather than mastectomy, which is total removal of the breast," said Jayaant Vaidya, a surgeon at University College London Medical School.
"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," he said.
"If this new technique is proved effective, it should make lumpectomy available to many more patients," he said. "Early tests are promising."
The technique was just as effective as six weeks of radiation in preliminary results from Vaidya's study of 29 women, which was prepared for presentation Monday at a meeting of the Radiological Society of North America.
The women all underwent lumpectomies for tumors of less than about 1½ inches. About half got the single dose and half received the standard six weeks of radiation. All have remained cancer-free during 1½ years of follow-up.
Since peak time for cancer recurrence is two to four years after treatment, it is too soon to call the technique a success, said Dr. LaMar McGinnis, senior medical consultant for the American Cancer Society.
But "so far, so good," Vaidya said.
Dr. Paula Schomberg, a Mayo Clinic radiologist, said the approach requires more study.
"It would certainly be advantageous if there was some way to replace an extended course of radiation with a shorter course, for patient convenience," she said. "It remains to be seen whether it's safe to do that."
The report said the technique is not sufficient for a form of breast cancer called lobular carcinoma, which accounts for up to 15 percent of all breast cancers. Vaidya said victims of such cancer still need an extended period of radiation but the radiating sphere can be used initially.
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