Studies on vitamin A and human cancer.

The work presented in this thesis deals with a study of serum retinol and related factors in patients with epithelial tumours (cervical, endometrial, and bladder carcinoma) and non epithelial tumours (malignant melanomas and sarcomas). In addition, dietary retinol and beta carotene intakes were measured in the epithelial cancer studies. The patients with cervical cancer had significantly lower serum concentrations of retinol, carotenoids, retinol binding protein (RBP) and prealbumin (PA) and significantly higher serum copper concentrations than both healthy volunteers and hospital controls. Serum concentrations of the parameters measured were similar in patients with pre-malignant cervical changes and hospital controls. Dietary preformed retinol, total retinol and beta carotene intakes of patients with malignant and pre-malignant cervical disease were not significantly different from hospital controls. Serum concentrations of retinol, carotenoids, RBP and PA were significantly lower in patients with advanced cervical cancer than in patients with early disease. Dietary intake of retinol and beta carotene was not lower in patients with advanced disease. Notable differences in serum and dietary parameters were observed between hospital controls and volunteers, and for some parameters larger differences occurred between the two groups of controls than between hospital controls and cancer patients. Possible reasons for this are discussed. Serum concentrations of retinol, RBP, and copper were similar in endometrial cancer patients and hospital controls. Serum concentrations of carotenoids were significantly lower in endometrial cancer patients than in controls. Serum retinol and associated factors were very similar in patients with transitional cell carcinoma of the bladder and in patients previously treated for bladder cancer; there were no significant differences between these two groups and the controls. Dietary intake in the three groups were also similar. In contrast to cervical cancer, the majority of patients with endometrial and bladder carcinoma had early disease. Serum concentrations of retinol, carotenoids, RBP and PA were significantly lower in patients with sarcomas when compared to hospital controls. In contrast, in patients with malignant melanoma the level of carotenoids and prealbumin in the serum were significantly lower than in controls while levels of retinol and RBP were similar to controls. Possible reasons for the lower levels of retinol and associated factors in some groups of cancer patients are discussed. The problems and limitations of estimates of dietary vitamin A intake are also discussed. The relationships of dietary vitamin A, and serum concentrations of retinol and carotenoids to human cancer are re-evaluated