Experimental studies have shown that PNI in PDAC is an active process involving reciprocal tumour–nerve signalling via neurotrophic factors (e.g., NGF, GDNF, CXCL12), extracellular matrix remodelling, and Schwann cell activation, which together create a permissive niche for perineural invasion [24]. Here, CXCL12 is linked to neoplasm.