Relationship between carotenoids and cancer. The multiple risk factor intervention trial (MRFIT) study

Abstract

We evaluated the baseline serum levels of beta carotene, total carotenoids, vitamin A and E, and retinol-binding protein among 156 initially healthy men who participated in the Multiple Risk Factor Intervention Trial (MRFIT) and who subsequently died of cancer and 311 controls individually matched for age, smoking status, randomization group, date of randomization, and clinical center. Both total carotenoids and beta carotene levels were lower in the 66 lung cancer cases than in their matched controls. For all cancer deaths combined, there were no significant differences in total carotenoids or beta carotene between cases and controls. The relationship between lower serum carotenoid levels and lung cancer persisted after adjusting for the number of cigarettes, alcohol intake, serum thiocyanate levels, and cholesterol levels in the blood. Serum levels of retinol, alpha tocopherol, and retinol-binding protein were not related to any cancer site. The results of this study provide further evidence for a possible protective effect of beta carotene against lung cancer among cigarette smokers.

Dietary and serum α-tocopherol, β-carotene and retinol, and risk for colorectal cancer in male smokers

“…This is in line with results from numerous other studies where no significant associations have been observed between pre-diagnostic blood levels of carotenoids and colorectal cancer (Schober et al, 1987;Connett et al, 1989;World Health Organization, 1998a). Nor have large, controlled trials demonstrated protective effects for b-carotene supplementation in colorectal cancer (Hennekens et al, 1996;Omenn et al, 1996;Albanes et al, 2000).…”

Blood concentrations of carotenoids and retinol and lung cancer risk: an update of the WCRF–AICR systematic review of published prospective studies

“…In total, 18 publications (17 cohort studies) were included in the analyses 4, 13, 17, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37 (Table 1). Fourteen studies (3143 cases) reported on β ‐carotene 4, 17, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, seven studies on α ‐carotene (1205 cases) 4, 13, 17, 23, 24, 25, 26 and β ‐cryptoxanthin (1205 cases) 4, 17, 23, 24, 25, 26, 27, six studies on lycopene (1097 cases) 4, 17, 23, 24, 25, 26, lutein and zeaxanthin (927 cases) 4, 17, 23, 24, 26, 27, and five studies on total carotenoids (724 cases) 4, 23, 24, 26, 29. Twelve studies (3192 cases) were on retinol 4, 23, 24, 25, 26, 27, …”

“…Twelve studies (3192 cases) were on retinol 4, 23, 24, 25, 26, 27, 28, 31, 34, 35, 36, 37. Nine publications were among men only 13, 26, 27, 28, 29, 30, 31, 33, 35 and nine publications were in both men and women 4, 17, 23, 24, 25, 32, 34, 36, 37. Eight studies were from United States, four studies from Europe, four studies from Asia, and one study from Australia (Table 1).…”

“…Nine studies (2958 cases) were included in the dose–response meta‐analysis 4, 17, 24, 25, 26, 27, 28, 29, 30. A significant inverse association was observed (Table 2).…”

“…Four studies (693 cases) were included in the dose–response meta‐analysis 4, 24, 26, 29. The summary RR for an increase of 100  μ g/100 mL was 0.66 (95% CI: 0.54–0.81, I ² = 0%, P heterogeneity  = 0.43) (Fig.…”