Radiation Treatments After Breast-Conserving Therapy for Elderly Patients

Abstract

Radiation treatments play an important role in the multidisciplinary management of most patients with breast cancer. Data from prospective phase III trials indicate that, for patients treated with a breast-conserving surgery, radiation reduces the risk of local recurrence, provides a clinically significant reduction in distant metastases, and improves overall survival. 1,2 Radiation treatments are also welltoleratedand,whendeliveredusingmoderntechnologies,carryalow risk of serious morbidity. However, there are also down sides to radiation treatments, most important of which are the inconvenience andcostsassociatedwithdailytreatmentsthatareadministeredovera 3- to 6-week period. Therefore, it would be ideal to identify favorable subgroups of patients treated with breast conservation for whom radiation could be avoided. In the past two decades, several randomized trials attempted to do this, but unfortunately most of these trials wereunsuccessfulatidentifyingagoodrisksubsetthatcouldbespared radiation. One notable exception was the Cancer and Leukemia GroupB(CALGB)9343trial,whichfoundthatpatientsolderthanage 70 with stage I, estrogen receptor (ER) ‐positive breast cancer who were treated with surgery and adjuvant tamoxifen without breast irradiation had a low 5-year local recurrence rate. In the article that accompanies this editorial, Hughes et al 3 report the 10-year results of this study. CALGB9343wasstatisticallydesignedasasuperioritytrialtotest whether radiation would reduce the probability of breast recurrence. With respect to this end point, the study was positive in favor of radiation. Specifically, the 10-year breast recurrence rates were 10% without radiation versus 2% with radiation (P .001). The updated report also demonstrated that the hazard of developing breast recurrence without radiation seemed similar between years 5 and 10 compared with thefirst 5 years of follow-up and that the risk would likely continue to increase after 10 years. This is consistent with previously published data indicating that ER-positive disease requires decades of follow-up to determine the true recurrence risk and the true magnitude of treatment benefits. 4