Preclinical and early clinical data suggest that immunotherapy is effective in patients with gastrointestinal cancers.

Knowledge of the relationship between tumour and tumour microenvironment including the immune system is essential.

Density of T cell infiltrates in colorectal cancer metastases was associated with response to chemotherapy.

High expression of programmed cell death ligand 1 in gastric cancer was related with poor prognosis.

To evaluate new immunological approaches with checkpoint inhibitors, prospective trials which include translational research are needed to identify biomarkers and select patients to optimise benefit.