[Vitamin A level and dark adaptation in patients with tumors].

Twenty patients with tumors of the head and neck region were found to have delayed dark adaptation. The serum vitamin A levels in these patients were significantly diminished in comparison with normal controls. Since disturbance of dark adaptation does not occur without prolonged vitamin A deficiency, it was reasonable to assume that the deficiency had been in existence for a long time. The antineoplastic effect of vitamin A is considered an important factor in tumor development and growth. Long-term malnutrition may be the reason for the disturbed vitamin A metabolism. Patients who do not attain mesopic vision should be advised against driving at night.