Background
Several good results of clinical trial of nivolumab or involving
nivolumab in advanced esophageal squamous cell carcinoma were reported.
However, the response rate was still poor. A rare phenomenon called the
“abscopal effect” refers to the regression of not only the irradiated
tumor but also non-irradiated distant tumors after local radiotherapy.
The mechanism is not completely clear, but it is thought that the
activation of anti-tumor immunity induced by radiotherapy is the main
factor.