Immunological Mechanisms Responsible for Radiation-Induced Abscopal Effect

Trends Immunol. 2018 Aug;39(8):644-655. doi: 10.1016/ Epub 2018 Jul 11.


Radiotherapy has been used for more than a hundred years as a local tumor treatment. The occurrence of systemic antitumor effects manifesting as regression of tumors outside of the irradiated field (abscopal effect) was occasionally observed but deemed too rare and unpredictable to be a therapeutic goal. This has changed with the advent of immunotherapy. Remarkable systemic effects have been observed in patients receiving radiotherapy to control tumors that were progressing during immune checkpoint blockade, stimulating interest in using radiation to overcome primary and acquired cancer resistance to immunotherapy. Here, we review the immunological mechanisms that are responsible for the ability of focal radiation to promote antitumor T cell responses that mediate tumor rejection and, in some cases, result in systemic effects.

Keywords: DNA damage; abscopal effect; antitumor immunity; immunotherapy; ionizing radiation; tumor microenvironment.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Review

MeSH terms

  • Animals
  • Apoptosis
  • Combined Modality Therapy
  • Humans
  • Immunotherapy / methods*
  • Lymphocyte Activation
  • Neoplasm Metastasis
  • Neoplasms / radiotherapy*
  • Radiotherapy / methods*
  • T-Lymphocytes / immunology*
  • Tumor Burden