A larger intergroup clinical trial showed that post-mastectomy radiotherapy had a mild effect on regression in older patients with early-stage breast cancer. The addition of radiotherapy to tamoxifen resulted in an absolute decrease in local recurrence rates of 6% to 7% compared to tamoxifen treatment alone. Adjuvant radiotherapy had no effect on ultimate breast preservation, distant metastases, breast cancer mortality, or all-cause mortality. In an advance summary of the paper reported at the American Society of Clinical Oncology meeting, Kevin S. Hughes, MD, of Massachusetts General Hospital in Boston, said, “During the 10-year follow-up period, 95 percent of patients had no distant metastases and essentially a 95 percent cure rate. In terms of survival, a large number of patients do die because we’re looking at an older population.” He went on to note that “almost all of the patients died from conditions other than cancer. There were eight breast cancer deaths in the tamoxifen group and 12 patient deaths in the group receiving tamoxifen plus radiation therapy. The main problem for these women was death from other causes. Death from breast cancer is a rare event for these older women with early, very small, clinically lymph node-negative breast cancers.” The results confirm and extend the findings of the intergroup clinical trial reported by the researchers after 8 years of follow-up (N Engl J Med 2004; 351: 971-77). In that report, as in the current study, the difference between the two groups was only a small decrease in recurrence rates. The findings are from the Cancer and Leukemia Group B (CALGB) 9343 clinical trial, which was designed to determine whether adjuvant radiotherapy plus tamoxifen treatment improves regression relative to tamoxifen treatment alone in women aged ≥70 years with stage I receptor-positive breast cancer. The study ultimately enrolled 636 patients, all of whom underwent breast-conserving surgery. The primary endpoints were time to locoregional recurrence, mastectomy due to recurrence, distant metastases, and breast cancer-specific and overall survival rates. After a median follow-up of 10.5 years, the addition of radiotherapy to tamoxifen significantly prolonged the time to first recurrence (P=0.015), which was the result of better local control with tamoxifen plus radiotherapy. Patients randomly assigned to tamoxifen alone had a 9% local recurrence rate and an 8% contralateral recurrence rate, compared with a 2% incidence of both regressions in patients treated with tamoxifen plus radiotherapy (P<0.001). Intramammary recurrence occurred in 6 patients in the radiotherapy group compared with 26 in the tamoxifen group. The 10-year probability of mastectomy-free was 96% in the tamoxifen-only group compared with 98% in the tamoxifen-plus-radiation group. 10-year breast cancer-specific and overall survival rates were 98% and 63%, respectively, in the tamoxifen group compared with 96% and 61%, respectively, in the radiotherapy group. "The question now is whether tamoxifen is adequate treatment for these small cancer patients aged ≥70 years." Hughes said, "Definitely, this needs to be discussed with patients, but I feel that it is very feasible to avoid radiotherapy in this group of patients." He also noted that when clinical trials began, the standard for a clean surgical margin was "no tumor ink stain," essentially a margin without a single cell. The current standard is 1 to 2 mm. "Currently, with larger margins, I think this reduction in recurrence rate will be even greater," Hughes said. Hughes said. ASCO President Douglas Blayney, MD, noted that the study's results are, at the very least, an affirmation of clinical practice and may lead to changes in clinical practice. "When my colleagues discuss the value of breast radiotherapy with older women and patients learn that the benefits are small, and many of those patients choose to defer radiotherapy, which has been the practice for about 20 years, I think this study gives us a degree of affirmative support that we, as physicians, can make decisions on behalf of our patients, and we can even change the advice we give to our patients. " Blayney, of the University of Michigan, noted.