Relative gene expression of DPYD, ECGF1, ERCC1, ERCC2, ABCB1, ABCG2, CYP3A4, UGT1A1, CES2, and TOP1 did not differ significantly between mucinous and nonmucinous tumours, although the difference in ERCC2 expression approached statistical significance (P=0.083), with higher expression in the mucinous subgroup. The gene discussed is CES2; the disease is neoplasm.