Dr. Susan Love Research Foundation | Study: Single-Dose Radiation is Effective Treatment for Some Women

A new study suggests that one single dose of radiation to the tumor bed at the time of surgery provides the same benefits as traditional radiation therapy that is delivered to the whole breast for five weeks.

The findings were published online in the Lancet and presented at the American Society for Clinical Oncology annual meeting on June 5.

The prospective international clinical trial, called TARGIT-A, was launched in March 2000. A randomized phase 3 trial, it enrolled 2232 women age 45 and older who had been diagnosed with ductal breast cancer and were scheduled to have a lumpectomy followed by radiation. Half of the women (1119) were assigned to a group that would receive the current standard of care: external whole breast radiation, which is delivered every day, for several weeks. The other half (1113) was assigned to the experimental group, which received one dose of radiation to the tumor bed with a special applicator at the time of surgery. (You can see a video of this procedure, called Intrabeam, being used during breast cancer surgery here.) If doctors discovered during the surgery that the tumor was lobular, or clear margins were not obtained, or met other specific criteria, the Intrabeam procedure was not performed and the women went on to receive traditional whole breast radiation.

The researchers followed the women to see if there was a difference in the two groups in the rate of local recurrence. After four years, there were six local recurrences among the group of women who had the Intrabeam procedure and five among the group who received the standard radiation treatment. The frequency of complications was similar in the two groups. In addition, because of how the radiation is delivered, the approach is not expected to have any long-term toxic effects on the heart or lungs.

Susan says:
Radiation therapy is an arduous part of breast cancer treatment. Each dose takes just seconds to deliver, but the therapy must be given daily, for five weeks. As a result, it's not uncommon for women, especially those who live in rural areas or who are elderly, to choose a mastectomy over a lumpectomy and radiation.

Furthermore, a recent study showed that women who do not receive radiation in a timely manner after their breast cancer surgery are more likely to have a recurrence than are those who proceed directly to radiation. Yet, at some centers there may be a waitlist to start radiation therapy. In other instances, women may face personal or health issues that cause them to delay treatment.

To improve this situation, researchers have been exploring the safety and effectiveness of new tools for providing radiation therapy. This study provides the first follow-up data we have from a phase 3 trial to test the Intrabeam approach. Other trials have and continue to test other techniques for providing partial breast radiation through brachytherapy, which can be done in five days.

One drawback of this study is that the women have only been followed for about four years. However, most local recurrences occur within two-to-three years after surgery, so the study participants have certainly passed that hurdle. Still, as the researchers point out, they will need to follow these women longer to determine whether those who had the single dose of radiation are more likely to have a new primary tumor occur in another area of the breast or a delayed recurrence in the same area.

Intrabeam is not an option for everyone. It requires specialized equipment that is not available at all hospitals. In addition, it was only given in selected situations. It was not given to women who had lobular breast cancer or to women who had cancer in more that one area of their breast. We also have to remember that the study findings apply to the types of tumors treated in this study: 86% were smaller than 2cm, 90% were hormone-sensitive, and 83% had no node involvement.

Even so, there is little doubt that these findings will lead more cancer centers to start using this new one-day treatment option for partial breast radiation. This could allow more older and rural women to choose a lumpectomy and radiation instead of a mastectomy. And it could permit many other women to spend less time having radiation and more time doing the things they enjoy.