A case report on the abscopal effect of liver-directed GRID radiotherapy

Abstract

GRID radiotherapy is a form of spatially fractionated radiotherapy that allows delivery of high radiation doses to bulky tumours. A grid splits the beam into multiple beamlets to give a heterogenous dose to the tumour, while stimulating the immune system to improve tumour response through the abscopal effect. However, this has fallen out of favour in recent times due to the presence of more modern techniques. Here we present a case of a large liver metastasis from a rectal neuroendocrine primary treated with GRID radiotherapy with an abscopal response seen in a portal vein tumour thrombus.