PTGS2 and cancer: Given the role of COX-2 expression not only in tumour cells (in many, but far from all cancer patients), but also in tumour endothelial cells [203], as well as in tumour-infiltrating leukocytes, it would be expected that the proposed combination of dietary intervention with COXIBs might be therapeutically useful for a vast majority of cancer patients, and not only for such cases where the tumour cells express COX-2, although it might be especially important for them.