Fish, vitamin D, and flavonoids in relation to renal cell cancer among smokers

Abstract

Fish, vitamin D, flavonoids, and flavonoid-containing foods may have cardiovascular benefits and therefore may also reduce the risk of renal cell cancer. Risk was prospectively assessed in the Alpha-Tocopherol Beta-Carotene Cancer Prevention Study (1985-2002) cohort (N = 27,111; 15.2 mean person-years of follow-up). At enrollment, demographic, health, and dietary history information was recorded. Individuals who smoked less than 5 cigarettes/day, with chronic renal insufficiency or prior cancer, were excluded. Hazard ratios and 95% confidence intervals from Cox regression were used to compare upper quartiles (quartiles 2-4) with the lowest quartile (quartile 1) of dietary intake. Among 228 cases, risk (quartile 4 vs. quartile 1) was associated with consumption of the flavonoid quercetin (hazard ratio = 0.6, 95% confidence interval: 0.4, 0.9; P(trend) = 0.015) and Baltic herring (hazard ratio = 2.0, 95% confidence interval: 1.4, 3.0; P(trend) < 0.001), with adjustment for age, body mass index, smoking, blood pressure, alcohol use, physical activity, urban residence, and education. In geographically stratified models, the risks associated with herring and total fish intake appeared to be highest in the urban coast region, although the interaction was not statistically significant. These results suggest that the flavonoid quercetin may prevent renal cell cancer among male smokers. The possible risk associated with fish intake warrants further investigation before conclusions may be drawn.

Figure 1.

Hazard ratio of renal cell cancer in relation to Baltic herring intake and body mass index, Alpha-Tocopherol Beta-Carotene Cancer Prevention Study, 1985–2002. The reference group was body mass index of ≤23.7 kg/m² and Baltic herring intake of ≤2.1 g/day, represented by the solid diamond. All hazard ratios were adjusted for age, body mass index, pack-years of smoking, systolic blood pressure, alcohol intake, leisure time physical activity, urban residence, educational level, and dietary intakes of quercetin and Baltic herring. All dietary intake variables were energy adjusted. Solid shapes indicate statistically significant hazard ratios. BMI, body mass index.