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 released last week. The study results, presented May 20 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 Dr. Kevin Hughes 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-positive (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 Dr. Douglas Blayney, 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.