Time-specific impact of trace metals on breast density of adolescent girls in Santiago, Chile

Whether trace metals modify breast density, the strongest predictor for breast cancer, during critical developmental stages such as puberty remains understudied. Our study prospectively evaluated the association between trace metals at Tanner breast stage B1 (n = 291) and at stages both B1 and B4 (n = 253) and breast density at 2 years post-menarche among Chilean girls from the Growth and Obesity Cohort Study. Dual-energy x-ray absorptiometry assessed the volume of dense breast tissue (absolute fibroglandular volume [FGV]) and percent breast density (%FGV). Urine trace metals included arsenic, barium, cadmium, cobalt, cesium, copper, magnesium, manganese, molybdenum, nickel, lead, antimony, selenium, tin, thallium, vanadium, and zinc. At B1, a doubling of thallium concentration resulted in 13.69 cm3 increase in absolute FGV (beta: 13.69, 95% confidence interval [CI]: 2.81, 24.52), while a doubling of lead concentration resulted in a 7.76 cm3 decrease in absolute FGV (beta: -7.76, 95%CI: -14.71, -0.73). At B4, a doubling of barium concentration was associated with a 10.06 cm3 increase (beta: 10.06, 95% CI: 1.44, 18.60), copper concentration with a 12.29 cm3 increase (beta: 12.29, 95% CI: 2.78, 21.56), lead concentration with a 9.86 cm3 increase (beta: 9.86, 95% CI: 0.73, 18.98), antimony concentration with a 12.97 cm3 increase (beta: 12.97, 95% CI: 1.98, 23.79) and vanadium concentration with a 13.14 cm3 increase in absolute FGV (beta: 13.14, 95% CI: 2.73, 23.58). Trace metals may affect pubertal breast density at varying developmental stages with implications for increased susceptibility for breast cancer. Trace metals occur in minute amounts and serve important functions in the human body. At unusually high levels, however, they potentially contribute to the pathogenesis of cancer. In this study, a possible role for trace metals in breast cancer was assessed in relation to pubertal breast density among Latino girls in Chile. Analyses show that select trace elements are linked to breast density. However, associations are inconsistent across pubertal timepoints. The findings suggest that breast development is marked by varying windows of susceptibility, during which mammary gland tissues are especially sensitive to exposure to specific environmental factors. image