Dietary carotenoids and risk of renal cell cancer in a pooled analysis of 12 cohort studies Free

2000

Renal cell cancer (RCC) is an uncommon cancer, but its incidence has been steadily increasing over the past few decades. RCC is the predominant type of kidney cancer, representing 80-85% of all kidney cancer cases. There is large international variation in RCC incidence rates, which implies that environmental factors, such as diet, may be important for the development of the disease. Many substances in plant foods, such as carotenoids, have been suggested to have anticarcinogenic potential, but the epidemiological evidence does not clearly support the hypothesis that intake of specific carotenoids may lower the risk of RCC. To better understand the relation of specific dietary carotenoids (alpha-carotene, beta-carotene, beta-cryptoxanthin, lutein/zeaxanthin and lycopene) and RCC risk, we analyzed the primary data from 12 cohort studies carried out in North America and Europe. Carotenoid intakes were estimated from food frequency questionnaires administered at baseline in each study. During up to 5 to 20 years of follow-up, 1,323 incident RCC cases were diagnosed among 767,366 participants within the 12 studies. Relative risks and 95% confidence intervals were calculated for each study using Cox proportional hazards models. The study-specific relative risks were pooled using a random effects model. The multivariate models were adjusted for age, body mass index, alcohol consumption, smoking habits, history of hypertension, parity, age at first birth and energy intake, which were modeled identically across studies. The pooled multivariate relative risks (95% confidence intervals) comparing the highest vs. lowest quartile of intake were 0.93 (0.80-1.09; p-value, test for trend 0.32) for alpha-carotene, 0.85 (0.71-1.01; 0.02) for beta-carotene, 0.85 (0.73-1.00; 0.26) for beta-cryptoxanthin, 0.91 (0.74-1.12; 0.06) for lutein/zeaxanthin and 0.99 (0.80-1.23; 0.57) for lycopene (among those cohorts that included tomato sauce in their food frequency questionnaire). The associations observed were similar between cohorts and for both genders. In summary, this study does not suggest that high intake of specific carotenoids, with the possible exception of beta-carotene, are associated with a substantial decrease in the risk of RCC.