Radiation-induced lymphopenia may negatively affect outcomes in patients receiving PD-1 directed immunotherapy

We thank the editors for the invitation to contribute to Therapeutic Radiology and Oncology and Chen et al . for their excellent piece “Key immune system markers in immunotherapy: absolute lymphocyte count, neutrophil to lymphocyte ratio, and alternative immune system metrics” in which they discuss our recently published work, “The Impact of Radiation Therapy on Lymphocyte Count and Survival in Metastatic Cancer Patients Receiving PD-1 Immune Checkpoint Inhibitors” (1).