The abscopal effect is a unique phenomenon in cancer treatment that occurs when radiation shrinks untreated tumors found elsewhere in the body in addition to the targeted tumor. The effect has a long history, dating back to the 1950s, but it doesn’t commonly occur in practice and the mechanisms are not fully understood. Research has shown that combining immunotherapy with radiation increases the rate at which the abscopal effect occurs. Understanding how it appears in practice could potentially lead to new cancer treatments and a novel approach to combining immunotherapies with radiation.