Initial results of a new study indicate that extra radiation treatment lowers the rate of breast cancer recurring in women who have had tumors surgically removed.
"These results are potentially practice-changing," said Timothy Whelan, an oncology professor at McMaster University of Canada and lead author of the clinical study.
Whelan presented the findings at the 47th annual meeting of the American Society of Clinical Oncology, being held in Chicago.
More than 1,800 women who had breast-conserving surgery participated in the study, receiving whole breast radiation (WBI) alone or WBI along with radiation to the surrounding lymph nodes.
Five years later, "there were statistically significant benefits for the group receiving the added (lymph node radiation) therapy," the study said.
Women who received radiation treatment to the breast and lymph nodes had a "41 percent lower rate of recurrences near the tumor site" compared to the women who received breast radiation alone.
They also had "a 36 percent lower rate of cancer recurrences in other parts of the body" after five years, the study said.
All of the women also had been treated with adjuvant chemotherapy or endocrine therapy.
Whelan said the findings "will encourage physicians to offer all women with node-positive disease the option of receiving regional nodal irradiation."
Adding the lymph node radiation, he added, "improved disease-free survival, lowered the risk of recurrences, and there was a positive trend toward improved overall survival, while not greatly increasing toxicities."