[Studies of vitamin A metabolism in malignant neoplasms]

Retinol concentration in the serum was determined in 600 healthy subjects and 250 cancer patients, including 116 patients with large bowel cancer, 90 with adenomas of the large bowel and 23 with cancer developing inn large bowel adenoma. Moreover, vitamin A concentration was determined in the liver obtained during autopsy from 23 patients dying from cancer and 34 dying from other chronic non-cancer diseases. A significantly lower serum retinol concentration was confirmed in patients with cancer, but it depended on the degree of disease progression, since a significantly lower retinol concentration in relation to healthy subjects was found only in advanced neoplasms. In patients with adenoma or cancer in adenoma the serum retinol level was normal. Moreover, retinol concentration lower before the operation returned to normal after the operation. On the other hand, in patients dying from cancer previous operation was without effect on the low serum retinol level. Tissue examinations showed significantly decreased vitamin A concentration in the liver of patients dying from cancer. The results of this study indicate that reduced serum retinol concentration is rather a consequence of the malignant process and is due to impaired retinol release from the liver blood. Long-lasting malignant process may also lead to an actual vitamin A deficiency in the organism.