Dietary boron and hormone replacement therapy (HRT) as risk factors for lung cancer in women

B58

Hormone replacement therapy (HRT) may reduce lung cancer risk. Dietary boron intake may have similar actions to HRT. However, no previous study has reported on the associations between dietary boron intake or the joint-effects of boron intake and HRT use on lung cancer. In an ongoing case-control study, we identified 763 women with newly diagnosed, histologically confirmed lung cancer and 838 matched healthy controls with data on both diet and HRT. Multiple logistic regression analyses were computed to assess the associations between dietary boron and HRT with lung cancer risk. After adjustment for potential confounders, including other dietary factors, the odds ratios (OR) and 95% confidence intervals (CI) for lung cancer with increasing quartiles of dietary boron intake were: 1.0, 0.84 (0.63-1.12), 0.72 (0.53-0.96), 0.51 (0.37-0.71), respectively for all women (P-trend<0.0001). When stratified by HRT, the highest quartile of boron intake among HRT users had much higher risk reduction than non-users (59% versus 40%). In joint-effects analyses, compared to women with high dietary boron intake who used HRT, the OR (95% CI) for lung cancer for low dietary boron intake and no HRT use was 2.07 (1.83-3.04). Current smokers, those with longer duration of smoking, heavier smokers, alcohol drinkers, and those with late stage disease had higher risk for lung cancer. Our findings suggest that boron intake from food sources in the typical U.S. diet is inversely associated with lung cancer in women, whereas women who consume low boron and do not use HRT are at substantial increased odds for the disease. These new findings warrant confirmation in future investigations.