Women 70 years of age or older with early-stage breast cancer did not benefit from the addition of radiation therapy to breast-conserving surgery and tamoxifen , according to the findings of a phase III randomized trial. The study results, presented May 20, 2010, in advance of the American Society of Clinical Oncology (ASCO) annual meeting , indicate that “death from breast cancer is a very rare event among [older] women with these small cancers,” said lead author Kevin Hughes, M.D., of Massachusetts General Hospital in Boston. The trial was conducted by three NCI clinical trials cooperative groups : the Cancer and Leukemia Group B, Eastern Cooperative Oncology Group, and Radiation Therapy Oncology Group.
Between 1994 and 1999, the researchers enrolled 636 women in the trial; 319 received tamoxifen alone after surgery, and 317 received tamoxifen plus radiation therapy. All women had early-stage, estrogen receptor (ER)-positive disease that had not spread to the lymph nodes. The researchers followed the women for a median of 10.5 years after treatment.
Although adding radiation therapy to tamoxifen reduced the chance of cancer recurrence in the same breast by 6 percent, it did not affect overall survival, breast-cancer-specific survival, cancer spread, or the need for later mastectomy due to disease recurrence. The 10-year breast-cancer-specific survival was 98 percent for women receiving tamoxifen alone and 96 percent for women receiving tamoxifen plus radiation therapy.
“Older women often have small tumors that are ER-positive, without evidence of spread to the lymph nodes. This [study] is certainly practice-affirming and may be potentially practice changing,” said Douglas Blayney, M.D., president of ASCO. “Many [older] women…elect to defer radiation therapy. This gives us some comfort as physicians in supporting that decision…and maybe it will change the recommendations we make to our patients,” he concluded.