Many studies indicated the capacity of LPS to be involved in the progression of various cancers: breast cancer via a ‘MyD88-BLT2’-linked signalling cascade [138], prostate cancer by activating the NF-κB pathway [139], gastric cancer through the LPS-NF-κB-PD-L1 axis [140], and oesophageal cancer [141]. Here, LTB4R2 is linked to gastric cancer.