BETA-CAROTENE, VITAMIN-A, AND LUNG-CANCER CHEMOPREVENTION - RESULTS OF AN INTERMEDIATE END-POINT STUDY

A randomized, placebo-controlled clinical trial of beta-carotene and r etinol was conducted with 755 former asbestos workers as study subject s. The targeted endpoint for the intervention study was a reduction in the incidence and prevalence of sputum atypia. The dosage of 50 mg be ta-carotene/d and 25 000 IU retinol/d on alternate days resulted signi ficant increases in serum concentrations of both agents with no clinic ally significant toxicity. Skin yellowing was observed in approximate to 35% of patients and may have contributed adversely to protocol adhe rence. Baseline analysis revealed that smoking and drinking were assoc iated with lower concentrations of serum beta-carotene, even after die tary carotene intake was adjusted for (P < 0.0001). Baseline concentra tions of retinol were apparently lowered by smoking (P < 0.002) and in creased by drinking (P < 0.0001). Drinking and smoking also were signi ficantly related to lower beta-carotene concentrations after supplemen tation (P < 0.001). No significant reduction in sputum atypia was obse rved after treatment.