Breast Cancer Radiation Does Not Affect Women’s Immune System

A new study shows that neither of two commonly used radiation treatments for early-stage, node-negative breast cancer has any effect on a woman’s immune system, even though women who receive five-day partial-breast radiation therapy (MammoSite® brachytherapy) (PBRT) have improved energy and quality of life compared to women who undergo six weeks of whole-breast radiation therapy (WBRT).

“One of the first questions a woman newly diagnosed with breast cancer asks is ‘what impact will radiation have on my body?’” said lead author Dr. Kevin Albuquerque, radiation oncologist at the Cardinal Bernardin Cancer Center, Loyola University Health System, Maywood, Illinois, U.S.A. “This study helps allay some fears.”

Albuquerque presented the research findings here today at the Canadian Association of Radiation Oncologists (CARO) 2007 annual meeting.

Traditionally, whole-breast radiation therapy has been the standard of care for early-stage, small-tumor, node-negative breast cancer. However, in the past five years, partial-breast radiation therapy has become available in many cities. Now both therapies are commonly used in cancer centers throughout the United States and Canada.

“PBRT is a viable option for women who are eligible,” said Albuquerque, assistant professor, radiation oncology, Loyola University Chicago Stritch School of Medicine, Maywood, Illinois, U.S.A.

For the study, 30 women, over age 45, who had a lumpectomy for early stage, small-tumor, node-negative breast cancer were divided into two treatment groups: the whole-breast radiation therapy group and the partial-breast radiation therapy group. The researchers administered psychological tests to all participants five times during the study: first, before any initiation of radiation therapy; second, at three weeks after completion of radiation therapy; and then at six-, nine- and 15-weeks post therapy.

The group of tests included one measuring tension, depression, anger, vigor and fatigue. Another measured well-being at the emotional, physical, functional and social levels. One test addressed aspects specific to breast cancer: appearance, illness, treatment side effects and sexuality.

Each time the tests were administered, blood samples were collected to assess natural killer cell activity and number of circulating lymphocyte subsets, indicators of immune system function.

Whole breast-radiation therapy targeted the entire breast with large-field radiation, while limiting risk to adjacent healthy tissue.

With partial-breast radiation therapy, a catheter is left in the woman for five days. When the patient comes in for a PBRT treatment, the catheter is then attached to a machine that delivers a radiation “seed” for therapy. Each time therapy is finished, the seed is taken out and the patient goes home. “No radiation seed remains in the breast overnight,” said Albuquerque.