Third line treatment of advanced oesophagogastric cancer: A critical review of current evidence and evolving trends

•Now evidence for chemo, immuno and targeted therapy in 3rd line treatment OG cancer.•Sequential treatment approaches are of benefit to a growing minority of patients.•Factors such as PS, prior response and tumour burden may identify potential responders.•Refining predictive biomarkers may further aid in effective patient selection. There is increasing evidence that treatment beyond second line provides significant survival benefit for selected advanced oesophageal and gastric adenocarcinoma patients, and important randomised controlled trials of both chemotherapy, targeted therapy and immunotherapy have recently been reported in this space. Despite this growing evidence base there are presently no formal guidelines for third line treatment available to clinicians, and as these agents move into routine clinical practice patient selection and rational sequencing of treatment will become an increasingly relevant clinical challenge. This review critically appraises the current evidence base for third line treatment and discusses patient selection, potential predictive biomarkers and future directions for third line treatment in this challenging condition.