Serum vitamins and the subsequent risk of bladder cancer

Purpose: We determined whether serum vitamins are inversely related to bladder cancer risk. Materials and Methods: A cohort of 9,345 Japanese-American men was examined from 1971 to 1977. At examination a blood specimen was obtained and the serum was frozen. After a surveillance period of more than 20 years 111 tissue confirmed incident cases of bladder cancer were identified. Stored serum and that of 111 age matched controls were tested by high pressure liquid chromatography for certain micronutrients, including lutein, zeaxanthin, anhydrolutein, alpha-cryptoxanthin, beta-cryptoxanthin, lycopene, dihydrolycopene, alpha-carotene, beta-carotene, total carotenoids, retinol, alpha-tocopherol, beta-tocopherol, gamma-tocopherol, delta-tocopherol and total tocopherols. Results: Based on quartiles of serum micronutrient levels the ORs for bladder cancer were determined using the general estimating equations approach. There were statistically significant inverse linear trends in risk for alpha-carotene (p<0.01), β-carotene (p=0.03), lutein plus zeaxanthin (p=0.03), β-cryptoxanthin (p=0.04) and total carotenoids (p=0.02). However, after adjustment for pack-years of cigarette smoking none of the inverse trends remained significant. Conclusions: These results suggest that cigarette smoking, which is a strong risk factor for bladder cancer, may explain the apparent protective effect of individual and total carotenoids against this common cancer.