Radiation following mastectomy can significantly reduce the risk of recurrence of breast cancer for patients with lymph node involvement or close surgical margins, according to report presented at the annual meeting of the American Society for Therapeutic Radiology and Oncology.

The researchers said they arrived at that conclusion by comparing results for 469 patients who had mastectomies followed by doxorubicin-based chemotherapy who also received postoperative radiatio to results for 1,031 patients not given postoperative radiation. The average follow up of all patients was ten years.

Recurrence rates for patients with involvement of 20 percent or more lymph nodes was reduced from 27 percent in patients who did not receive radiation to 11 percent in those treated with radiation. For patients with less than 20 percent lymph node involvement, this reduction was from 12 percent to 4.2 percent. Recurrence for patients with close or positive cancer margins (cancer found in the area directly surrounding the tumor) was decreased from 45 percent in patients not given radiation to 13.3 percent in those who did receive radiation.

"According to our data, there are certain patients who can greatly benefit from post-mastectomy radiation," said Dr. Wendy A. Woodward of the Department of Radiation Oncology at the M.D. Anderson Cancer Center in Texas and lead author of the study. "Patients whose cancer involves 20 percent or more of the removed lymph nodes or who have close or positive surgical margins can significantly reduce their chances of a recurrence with postoperative radiation therapy."

Other sources: American Society for Therapeutic Radiology and Oncology