Stereotactic body radiation therapy decreases distinct peripheral blood immunophenotypes. Peripheral blood cell counts of (A) CD3+, CD4+, and CD8+ T cells and the percentages of CD4+CD25+CD127lo regulatory T cells and (B) CD56+CD16+ and CD56brCD16− natural killer cells in all patients pretreatment/baseline (PRE), end of treatment (EOT), and 3 months posttreatment (3MO) samples, with healthy volunteers (HV) included as reference data.