Radiation therapy as an adjuvant treatment after sentinel lymph node surgery for breast cancer

In this article, we have suggested that radiation can be an important adjuvant to sentinel lymph node surgery. Combining radiation with sentinel lymph node surgery has the potential to minimize the risk and consequences of false-negative surgery and can be used in selected cases as the definitive axillary treatment after finding a positive sentinel lymph node. In addition, radiation can be used as definitive therapy for patients at risk for IMC involvement. The radiation treatment fields after sentinel lymph node surgery need to be individualized, depending on the characteristics of the case. In general, we use standard tangent beams with the breast as the target volume for patients with unifocal breast cancer and negative sentinel lymph nodes treated initially by an experienced surgeon. We include the breast and the majority of Level I and II axilla within the irradiated target volume for patients with negative sentinel lymph nodes who have one of the following features: (1) unknown or inexperienced surgeon, (2) multifocal breast cancer, or (3) neoadjuvant chemotherapy. We include this target volume by contouring these structures on a three-dimensional treatment planning system and designing our tangent fields with a raised and nondivergent cranial field edge and a field edge deep enough to cover the low axilla. For patients with positive sentinel lymph nodes, we recommend axillary dissection. For patients who do not undergo a dissection, we use the high tangent fields described above if the primary disease is under 2 cm and the axillary disease is 2 mm or less and present in a single lymph node, provided there is no lymphovascular space invasion or extracapsular disease. For all other sentinel lymph node-positive patients, we match fields above the tangent fields to treat the axillary apex and supraclavicular fossa. The upper IMC lymph nodes are contoured and included in tangent fields for patients with primary drainage to this site or dual drainage to this site with a positive axillary sentinel lymph node. If too much lung or heart is included in these fields, alternative field arrangements are sought, but if none are feasible, the IMC is left untreated. The radiation dose is calculated for all contoured nodal structures, and supplemental fields are used to assure that the regions are treated to the prescribed dose. These treatment policies are based more on scientific rationale rather than scientific outcome data. Clearly, more research is needed to assess the value of radiation as an adjuvant modality for regional treatment after sentinel lymph node surgery.