This general “sideness” of the prognostic impact of CDX2 expression may be related to the massive enrichment of CDX2-negative tumours in the medullary subtype of CRC, which is almost exclusively located in the right-sided colon and is associated with a comparatively benign clinical behaviour and thus probably narrows the potential worse prognostic effect of CDX2 loss in other CRC subtypes. The gene discussed is CDX2; the disease is neoplasm.