Retinol and postoperative colorectal cancer patients.

In order to determine whether low plasma levels of retinol and its carrier (retinol binding protein) are related to increased risk of cancer recurrence, these were measured in 103 patients who had had colorectal cancer surgically removed. According to the modification of the Dukes' classification, 66 had B2 tumours (with no nodal involvement' and 37 had C tumours (with lymph-node metastases). These patients were part of the Cross Cancer Institute Adjuvant GI Cohorts who were on the control arms receiving no further treatment. At the time of blood sample collection, they were believed to be free of neoplastic disease. The post-operative patients were found to be associated with subnormal circulatory levels of retinol (43.3 micrograms dl-1 vs 65.3 micrograms dl-1) and its carrier protein (4.6 mg dl-1 vs 5.7 mg dl-1), when compared with apparently healthy subjects. The latter being more markedly depressed in patients with "C" type tumour (3.8 mg dl-1) than that in those with "B2" type tumour (5.0 mg dl-1). These findings appeared to be persistent during the follow-up study when a second blood sample was collected, one to four months later from 40 patients. Furthermore, the initial plasma retinol level in conjunction with RBP was found to be even lower in 12 patients (35.1 micrograms dl-1, 3.7 mg dl-1) who subsequently had cancer recurrence than in those who remained free of apparent cancer (44.5 micrograms dl-1, 4.6 mg dl-1). The lowest initial values of retinol (19.3 micrograms; 18.8 micrograms dl-1) and RBP (2.4; 1.6 mg dl-1) recorded in the study were seen in the only two patients who died of the disease at the time of follow-up.