E5422. Imaging of Oncology Patients on Treatment: Identifying Treatment-Related Toxicities and Avoiding Response Assessment Pitfalls
  1. Engy Abbas; McMaster University
  2. Rahul Sarkar; McMaster University
  3. Christian Van Der Pol; McMaster University
  4. Prasa Gopee-Ramanan; McMaster University
  5. Michael Patlas; University of Toronto
  6. Atul Shinagare; Harvard University
Patients undergoing treatment for cancer may experience a variety of adverse events relating to their treatment, which may range in severity from sub-clinical to life-threatening. Imaging plays an important role in the detection and characterization of several such adverse effects, but requires radiologists to recognize findings that can often be subtle, have overlapping features with other pathologies, and can sometimes be mistaken for disease progression. Furthermore, more recent treatment advances in cancer care utilize mechanisms associated with toxicity profiles that differ from those of traditional therapies and are associated with unique imaging manifestations. The purpose of this exhibit is to provide an up-to-date primer on imaging features of treatment-related toxicities in patients with cancer and to highlight some of the associated pitfalls in response assessment.

Educational Goals / Teaching Points
Discuss the current major classes of cancer treatment and associated mechanisms underlying imaging manifestations of treatment toxicity and response. Review imaging findings of the most common and important toxicities across treatment types. Consider pitfalls leading to detection or interpretation errors for both toxicities and treatment response assessment. Present an organized approach of these considerations to facilitate imaging evaluation of patients with cancer across treatment types.

Key Anatomic/Physiologic Issues and Imaging Findings/Techniques
1. Mechanisms of treatment-related toxicities by class: a. conventional chemotherapy, b. molecular targeted therapy, c. immunotherapy, d. hormone therapy, e. hematopoietic stem cell transplantation, and f. radiation therapy. 2. Treatment-specific pitfalls in response assessment: a. molecular targeted therapies (e.g., myxoid degeneration in GIST, intratumoral hemorrhage, pseudoprogression), b. immunotherapy (e.g., pseudo progression, sarcoidlike reaction), and c. advanced 3D conformal external-beam radiation (e.g., irregular patterns of fibrosis post-SBRT). 3. Systems-based checklist approach: a. lungs, b. hepatobiliary, c. gastrointestinal, d. genitourinary, e. vascular, f. pleura and peritoneum, and g. others.

An organized approach is presented to facilitate imaging diagnosis of cancer treatment-related toxicities and avoiding associated pitfalls in response assessment.