SummarySerum There is considerable evidence from case-control studies that a low serum level of vitamin A is an important risk factor for the development of a variety of human cancers of epithelial cell origin [1][2][3][4][5][6][7][8]. Several of these studies [1,[4][5][6]8 ] have also indicated that the presence of an established cancer is associated with low serum concentrations of the vitamin A transport proteins, which include retinol-binding protein (RBP) and prealbumin. Furthermore, in our recent study [9] where serum vitamin A and RBP levels were measured in patients with surgically resected cancers of the colon and rectum, those who subsequently had recurrent disease showed lower levels of vitamin A and RBP compared with those who remained free of recurrence. Low RBP levels in plasma have also been reported in patients with recurrence of breast tumors, when compared with the

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