ATM and gastric cancer: ATM (ataxia-telangiectasia mutated) plays a key role in the cellular DNA damage response (DDR) [9–11], and is emerging as an important tumour-suppressor biomarker in many malignancies, as supported by data suggesting that 15% of gastric cancers carry ATM mutations [12, 13] and that ATM deficiency is prevalent in lymphoid malignancies [14, 15].