Journal of Clinical OncologyTime to Debunk an Urban Myth? The “Abscopal Effect” With Radiation and Anti–PD-1

The term abscopal effect (from Latin, ab, meaning “away from,” and scopus, meaning “target”) was coined in 1953, specifically referring to effects of ionizing radiation outside the radiated tumor volume. Does the evidence show that, contrary to widely held perception in the field, the abscopal effect is exceedingly rare and is not clinically relevant when using anti–PD-1/PD-L1 therapies and stereotactic body radiation therapy (SBRT) for head and neck cancer (HNC)?