Carotenoids and the risk of developing lung cancer: a systematic review

• Published in: The American journal of clinical nutrition Vol. 88; no. 2; pp. 372 - 383
• Main Authors: Gallicchio, Lisa, Boyd, Kristina, Matanoski, Genevieve, Tao, Xuguang (Grant), Chen, Liwei, Lam, Tram K, Shiels, Meredith, Hammond, Edward, Robinson, Karen A, Caulfield, Laura E, Herman, James G, Guallar, Eliseo, Alberg, Anthony J
• Format: Journal Article
• Language: English
• Published: Bethesda, MD American Society for Nutrition 01.08.2008; American Society for Clinical Nutrition; American Society for Clinical Nutrition, Inc
• Subjects: Adult; Aged; Aged, 80 and over; anticarcinogenic activity; Antioxidants; beta-carotene; Biological and medical sciences; carotenoids; Carotenoids - administration & dosage; Carotenoids - blood; Clinical trials; Diet; Dietary Supplements; Feeding. Feeding behavior; Female; Fruit; Fundamental and applied biological sciences. Psychology; human health; Humans; literature reviews; Lung cancer; lung neoplasms; Lung Neoplasms - blood; Lung Neoplasms - epidemiology; Lung Neoplasms - etiology; Male; Meta-analysis; Middle Aged; nutrient intake; Nutritional Status; Prospective Studies; randomized clinical trials; Randomized Controlled Trials as Topic; Risk Factors; risk reduction; Smoking; smoking (habit); Smoking - adverse effects; Vegetables; Vertebrates: anatomy and physiology, studies on body, several organs or systems; Human; Lung disease; Respiratory disease; Lung cancer; Risk factor; Development; Bronchus disease; Malignant tumor; Review; Carotenoid; Cancer
• ISSN: 0002-9165; 1938-3207
• DOI: 10.1093/ajcn/88.2.372

BACKGROUND: Carotenoids are thought to have anti-cancer properties, but findings from population-based research have been inconsistent. OBJECTIVE: We aimed to conduct a systematic review of the associations between carotenoids and lung cancer. DESIGN: We searched electronic databases for articles published through September 2007. Six randomized clinical trials examining the efficacy of β-carotene supplements and 25 prospective observational studies assessing the associations between carotenoids and lung cancer were analyzed by using random-effects meta-analysis. RESULTS: The pooled relative risk (RR) for the studies comparing β-carotene supplements with placebo was 1.10 (95% confidence limits: 0.89, 1.36; P = 0.39). Among the observational studies that adjusted for smoking, the pooled RRs comparing highest and lowest categories of total carotenoid intake and of total carotenoid serum concentrations were 0.79 (0.71, 0.87; P < 0.001) and 0.70 (0.44, 1.11; P = 0.14), respectively. For β-carotene, highest compared with lowest pooled RRs were 0.92 (0.83, 1.01; P = 0.09) for dietary intake and 0.84 (0.66, 1.07; P = 0.15) for serum concentrations. For other carotenoids, the RRs comparing highest and lowest categories of intake ranged from 0.80 for β-cryptoxanthin to 0.89 for α-carotene and lutein-zeaxanthin; for serum concentrations, the RRs ranged from 0.71 for lycopene to 0.95 for lutein-zeaxanthin. CONCLUSIONS: β-Carotene supplementation is not associated with a decrease in the risk of developing lung cancer. Findings from prospective cohort studies suggest inverse associations between carotenoids and lung cancer; however, the decreases in risk are generally small and not statistically significant. These inverse associations may be the result of carotenoid measurements' function as a marker of a healthier lifestyle (higher fruit and vegetable consumption) or of residual confounding by smoking.