Breast cancer is the most frequently diagnosed cancer among women in the United States, excluding cancers of the skin, and the second most common cause of cancer-related mortality. Imaging techniques such as mammography and ultrasound have long been important in the screening, diagnosis, and treatment of breast cancer. Recent advances in imaging techniques, computer software, and robotics have led to the development of new image-guided radiation therapy (IGRT) techniques to improve the accuracy of radiation therapy in patients with breast cancer. Radiation therapy is an important part of the standard of care for women with breast cancer, and is often used in combination with breast-conserving surgery ("lumpectomy") for patients with early disease. Accurate targeting of radiation therapy is essential to kill tumor cells while sparing surrounding healthy tissues, and advances in 3-dimensional computed tomography (CT) scanning and treatment planning now make it possible to provide radiation treatment that is closely matched to the shape of the patient's tumor. However, radiation therapy for most patients involves a series of radiation therapy sessions (eg, 5 days per week for 6 weeks), and the accuracy of treatment may be decreased by patient motion between sessions (eg, changes in how the patient is positioned on the treatment couch from one session to the next) or during the treatment session (eg, movement due to pain or breathing motion). IGRT provides a set of techniques in which imaging technologies (including fluoroscopy, CT scanning, positron emission tomography, and ultrasound) are incorporated into daily radiation treatment in order to improve the targeting accuracy of radiation therapy. IGRT approaches have been extensively studied in other types of cancer (eg, prostate cancer) and are increasingly being used for patients with breast cancer. These techniques have the potential to significantly reduce the amount of healthy tissue that is irradiated during cancer therapy, resulting in better treatment safety and tolerability. Ensuring patient comfort and proper positioning are essential to achieve the potential benefits of IGRT.
After reading this article, the participant should be able to:
- Define how radiation therapy is used in patients with breast cancer.
- Discuss different ways in which radiation may be administered.
- Summarize the defining characteristics of intensity modulated radiation therapy and image-guided radiation therapy (IGRT).
- Distinguish the different types of IGRT systems that are used in cancer therapy.
- Describe some of the limitations of IGRT and potential directions for future research.