Table 1.

Biomarkers suggested to predict neoadjuvant treatment response in rectal cancer

Category	Type	Parameter
Molecular genetic markers	DNA mismatch repair [11–21]	dMMR, MSI, MSI-H
	MAPK/ERK and PI3K/AKT/mTOR pathways [22–37]	EGF, EGFR, VEGF, RAS, KRAS, BRAF, PTEN, NF1
	Tumour suppressors and oncogenes [38–46]	TP53, XIAP, TCF4
	Transcriptome/Epigenome [47–71]	Transcriptomic and epigenetic signatures, miR-130a, miR-487a-3p, TIMP3 methylation
Immunological markers	Blood-based immunological markers [72–86]	P/L ratio, N/L ratio, cytokines, C-reactive protein
	Tissue-based immunological markers [87–119]	LNR, TILs, PD-1 and PD-L1
Other biomarkers	Blood-based cancer markers [120–139]	CTCs, cfDNA, ctDNA, CEA
	Gut microbiota [140–144]	Fusobacteria, Bacteroidales, Duodenibacillus massiliensis

Abbreviations: dMMR Mismatch repair deficient, MSI Mismatch repair instable, MSI-H Mismatch repair instable-high, EGF Epidermal growth factor, EGFR Epidermal growth factor receptor, VEGF Vascular endothelial growth factor, RAS Rat sarcoma, KRAS Kirsten rat sarcoma, BRAF V-raf murine sarcoma viral oncogene homolog B1, PTEN Phosphatase and tensin homolog, NF1 Neurofibromin 1, TP53 Tumour protein p53, XIAP X-linked inhibitor of apoptosis protein, TCF4 Transcription factor 4, TIMP3 Tissue inhibitor of matrix metalloproteinases 3, P/L ratio Platelet-to-lymphocyte ratio, N/L ratio Neutrophil-to-lymphocyte ratio, LNR Lymph node ratio, TILs Tumour infiltrating lymphocytes, PD-1 Programmed cell death protein 1, PD-L1 Programmed death-ligand 1, CTCs Circulating tumour cells, cfDNA Cell-free DNA, ctDNA Circulating tumour DNA, CEA Carcinoembryonic antigen