Integration of systemic therapy and radiation therapy for patients with early-stage breast cancer treated with conservative surgery.

There is no consensus on the optimal combination of systemic therapy and radiation therapy for patients with early-stage breast cancer treated with conservative surgery. This article reviews prospective and retrospective studies that shed light on this topic. Patients with positive, close, or unknown microscopic margins appear to benefit from relatively early initiation of radiation therapy, whereas those with wider tumor-free margin widths do not. For patients at high risk of distant failure (such as those with = 4 positive axillary nodes), chemotherapy may be more effective when it begins before radiation therapy rather than after. Regimens of concurrent radiation therapy and chemotherapy tend to have higher acute and subacute complication rates than sequential regimens, but the actual rates vary substantially with the exact details of the overall treatment program. There are no data on the impact of the timing of tamoxifen administration on the effectiveness of radiation therapy. Tamoxifen does not appear to increase complication rates relative to the use of radiation therapy alone. Thus, the best way of giving combined-modality therapy is uncertain. Further retrospective and prospective studies to investigate the issues discussed herein should be performed.