Thymidine phosphorylase expression and effect of doxifluridine: A phase IIstudy

Doxifluridine (5 ' -DFUR), an active intermediate metabolite of capecitabin e, is converted to 5-fluorouracil by thymidine phosphorylase (TP). We used immunohistochemical staining to investigate the relation between TP express ion and 5 ' -DFUR effects in 40 patients with advanced/recurrent lung metas tases from colorectal cancer. Cox regression analysis suggested that TP-pos itive cancer cells (risk ratio 3.72), were independent factors in survival whereas factors in progression-free survival were TP-positive cancer cells (2.93), and TF-positive stromal cells (0.24). It is suggested that TP expre ssion in cancer cells and in stromal cells are opposite prognostic factors in patients treated with 5 ' -DFUR.