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

Abstract

Objective: To study the association between dietary and serum antioxidant vitamins and carotenoids and risk for colorectal cancer in male smokers. Design: A prospective cohort study within a randomised, double-blind, placebo-controlled trial testing supplementation with atocopherol (50 mg=day), b-carotene (20 mg=day) or both in preventing cancer. Subjects and methods: Participants of the Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study with complete dietary data and serum samples available from baseline. These included 26 951 middle-aged male smokers among whom 184 colorectal cancer cases were diagnosed during 8 y of follow-up. Relative risks were calculated with Cox proportional hazards models adjusting for trial supplementation, age, body mass index, serum cholesterol, cigarettes smoked per day and physical activity. Results: There was no significant association between dietary vitamin C or E, a-or g-tocopherol, retinol, a-or b-carotene, lycopene or lutein þ zeaxanthin and risk for colorectal cancer. Serum a-tocopherol, b-carotene or retinol was also not associated with the risk, neither did the season when baseline blood was drawn modify the relationship between serum b-carotene and colorectal cancer risk. Conclusions: Our data support the results from previous studies in which no association between dietary antioxidant vitamins and carotenoids and risk for colorectal cancer has been observed. Likewise, no association between baseline serum antioxidant concentrations and colorectal cancer risk was evident.

Plasma and dietary carotenoids and vitamins A, C and E and risk of colon and rectal cancer in the European Prospective Investigation into Cancer and Nutrition

“…Two prospective studies observed no association with CRC for carotenoids and tocopherols, although a pooled analysis of five cohort studies on atocopherol suggested a slight inverse association. 10,12,13 An inverse association with CRC has also been reported for circulating retinol in one of three previous studies. [10][11][12] The large number of cases in this study is one of its great strengths, together with the prospective design and information on a wide range of confounders.…”

“…10,12,13 An inverse association with CRC has also been reported for circulating retinol in one of three previous studies. [10][11][12] The large number of cases in this study is one of its great strengths, together with the prospective design and information on a wide range of confounders. It is possible that previous studies were unable to detect associations with CRC or subsite-specific associations, because of the low number of included cases (ranging from 88 to 184).…”

“…9 Studies examining the association between blood concentrations of carotenoids and vitamins A, C and E with CRC risk have generally been inconclusive as well and have reported only suggestive risk reductions for carotenoids (most notably b-carotene) and vitamins A (retinol) and E (tocopherols). [10][11][12][13] None of these studies distinguished between proximal and distal colon cancer types. However, etiological pathways underlying colon cancers proximal to the splenic flexure are different from those distal to the splenic flexure and evidence that risk factors for tumors originating from different colorectal subsites vary is accumulating.…”

Fruits, Vegetables, and Antioxidants and Risk of Gastric Cancer among Male Smokers

“…The between-run coefficients of variation were 2.2% for a-tocopherol, 3.6% for h-carotene, and 2.4% for retinol (21).…”

Kolorektale Karzinome: Neue Entwicklungen in der Tumorprävention und in der Diagnostik der Tumorausbreitung

“…Dazu gehören Kalzium, Magnesium, β-Carotin, Vitamin A, C, D, E, Folsäure und Selen [36]. Im Fall von Vitamin A und C sah die Leitliniengruppe keinen eindeutigen Beleg für eine Senkung des KRK-Risikos durch eine regelmäßige Einnahme des Vitamins [21,32,37,38]. Für Vitamin D ist die Datenlage ebenfalls unzureichend, um eine sichere Aussage über einen möglichen protektiven Effekt treffen zu können [32,[37][38][39].…”