Pearls and Pitfalls in the Imaging of Targeted Therapy and Immunotherapy in Lung Cancer

Most lung cancers are diagnosed at advanced stage when the cancer has metastasized outside the lung. These patients are not eligible for curative surgery or radiation therapy and treated with systemic therapy. Advances in the understanding of the biology of lung cancer has resulted in the development of targeted therapy aimed at specific genetic mutations identified with non-small cell lung cancer and immunotherapy that helps the immune system recognize tumors as foreign, stimulates the immune system, and removes the inhibition that allows growth and spread of cancer cells. Tumors treated with targeted or immunotherapies respond differently when compared with traditional chemotherapy and not captured by conventional response criteria such as the World Health Organization criteria and Response Evaluation Criteria in Solid Tumors. Therefore, several modified criteria have been developed to appropriately address the treatment response when using these novel agents. Numerous treatment-related side effects have been described that are important to recognize to avoid misinterpretation as worsening tumor and to ensure appropriate management.