What term describes the initial swelling of tumors due to immune checkpoint inhibitors, which may be mistaken for tumor growth?

The term that refers to the initial swelling of tumors caused by immune checkpoint inhibitors, which can be misinterpreted as tumor growth, is pseudoprogression. This phenomenon is particularly relevant in the context of immunotherapy, as these treatments can lead to an inflammatory response within tumors. Such inflammation often manifests as increased tumor size or new lesions on imaging studies. However, instead of indicating actual disease progression, this swelling represents an immune-mediated response, reflecting the body's activation against cancer cells.

Understanding pseudoprogression is crucial for interpreting imaging results in patients undergoing immunotherapy. This misinterpretation emphasizes the importance of correlating clinical evaluation with imaging findings to avoid premature changes in treatment plans based on initial appearances of tumor burden.