Intensity-Modulated Radiation Therapy for Breast: Is It for Everyone?

Intensity-modulated radiation therapy (IMRT) became available to the radiation oncology community in the late 1990s, and its initial applications were to increase conformality of dose to the target, allowing for both dose escalation and decreased radiation to adjacent normal organs. In most disease sites, these continue to be the goals of IMRT. However, for breast cancer, IMRT has emerged with a different endpoint, namely improving dose homogeneity throughout the targeted breast. In 2 recent prospective randomized trials comparing IMRT with “standard” planning, IMRT was associated with a significant decrease in both acute side effects and late fibrosis, which was related directly to dose homogeneity. Better conformality can also be achieved with IMRT; yet because of the unique location of the breast tissue external to the thoracic contents, attempts at “inverse planning” with multiple fields were largely not perceived as “better” plans when treating the breast alone. Research is underway to determine if the use of IMRT for breast or chest wall along with regional lymphatics may improve outcomes over “standard” treatment planning. Additionally, special anatomic situations, such as pectus excavatum, have been shown to benefit from IMRT.