Women suffering from breast cancer in its incipient stage could benefit from a shorter, more intense course of radiation running three weeks instead of the conventional five, Canadian researchers said on Monday during the annual meeting of the American Society for Therapeutic Radiology and Oncology in Boston.

In the US, a number of 182,000 women develop breast cancer annually. Approximately 40 percent need to undergo radiation treatment in order to prevent the cancer from reoccurring in the same breast. The findings of the study are encouraging, as clinics will now have the chance to treat more women. Presently, almost 30 percent of the patients who need chemotherapy avoid it by choosing a mastectomy over a lumpectomy plus radiation treatment.

The study involved 1,234 Canadian women who were randomly assigned to either accelerated radiation treatment or standard therapy between 1993 and 1996. The accelerated radiation treatment requires three weeks of daily, 15-minute visits compared to five weeks of standard therapy and cost-two-thirds as much.

The women were then followed for a period of 12 years. After that period, cancer had returned in 6.2 percent of patients treated with accelerated radiation therapy, compared to 6.7 percent of patients given standard therapy.

“We were surprised that the risk of local recurrence and side effects for women treated with accelerated whole breast irradiation was so low even at 12 years,” said Dr. Timothy Whelan of McMaster University in Hamilton, Ontario, lead author of the study.

Another interesting study presented at the same conference by Dr. Peter Beitsch, a surgical oncologist at Medical City Dallas Hospital, Dallas promoted another therapy in the case of breast cancer patients. The therapy involves just one week of radiation instead of the conventional five or six.

Known as accelerated partial breast irradiation, the procedure focuses radiation at the site of the removed tumor using a special single balloon catheter that delivers the radiation through tiny radioactive seeds. Dr. Beitsch reported on outcomes among the first 400 women in his registry. About four years after treatment, a little more than 2 percent of the breast cancer patients who had breast-conserving surgery followed by weeklong radiation regimen had recurrences of their cancer.

“It is fair to say that the technique is controversial in the radiation and oncology community, in part because we haven’t had good long-term follow-up data on the patients who have had it. Obviously, we will know more when we have been following these patients longer, but the early follow-up data are encouraging,” Dr. Beitsch said.

The procedure was approved by the FDA in 2002 but is not widely used for the treatment of breast cancer because lack of longer studies on its efficiency. However, Dr. Beitsch said that it is a safe, convenient treatment which may actually increase the rate of breast conservation, since women choose mastectomy because they live too far from a radiation center and cannot afford the time and expense of six to seven weeks of living or traveling to the center.

Women age 45 years or older, with tumors of three centimeters or less and a diagnosis of ductal cancer or ductal cancer in situ (DCIS) are the best candidates for this kind of therapy, Dr. Beitsch concluded.