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E1759. Radiotherapy-Induced Side Effects: CT Common Imaging Findings in Breast Cancer Patients
Authors
  1. João Garrido Santos; IPO Porto
  2. Susana Lopes; IPO Porto
  3. Ligia Gonçalves; IPO Porto
  4. Margarida Gouvêa; IPO Porto
Background
Breast cancer is one of the most common malignancies in women. Nowadays, many patients undergo breast-conserving surgery followed by radiation therapy, and it is recommended to reduce the risk of local recurrence. Tangential external beam radiation is the most common type of radiotherapy administered for the treatment and affects not only the malignant tumor but also the surrounding normal tissues. The purpose of this exhibition is to review Computed Tomography (CT) imaging findings of external-beam radiotherapy-induced side effects in breast cancer patients.

Educational Goals / Teaching Points
Radiologic manifestations after radiation therapy are usually confined to the tissue within the radiation field and are dependent on the interval after completion of treatment. Radiation-induced complications may be classified into three groups based on the time sequence of occurrence. In the acute phase, breast edema, steatonecrosis, irregular calcifications, radiation pneumonitis, pleural effusion and focal liver edema are common complications. In an intermediate phase that occurs after months to years after radiation treatment, bone fracture, pulmonary fibrosis and pericardial disease are some common findings. Cardiomyopathy, liver fibrosis and radiation-induced malignancies such as carcinomas involving lung, contralateral breast, squamous cell carcinoma of the esophagus, sarcomas of the chest wall and osteossarcomas are some rare long-term complications.

Key Anatomic/Physiologic Issues and Imaging Findings/Techniques
CT is more sensitive and demonstrates radiation induced changes earlier than chest radiography and is much more useful in evaluating distribution and pattern of these lesions. It was performed a bibliographic review and a retrospective analysis of the CT imaging findings of external-beam radiotherapy induced side effects in breast cancer patients. A Picture Archiving and Communication System (PACS) digital archive was searched in our institution for this purpose.

Conclusion
A comprehensive understanding of the complete spectrum radiation-related side effects is essential to manage patients treated with radiotherapy. It is also important to be aware of the potential long-term effects, including the occurrence of secondary neoplasms.