Researchers Find Why Early Puberty Increases Breast Cancer Risk
A growing body of evidence has found a link between early puberty and increased risk of breast cancer later in life. A study published today in the Journal of Adolescent Health has given new insights as to how this association occurs.
In 2004, the longitudinal study recruited 183 girls, aged six to seven years old, and followed their pubertal maturation through 2018, measuring age at onset of puberty, adult height, peak height velocity, and hormonal factors that have been associated with increased breast cancer risk in adult women: levels of insulin-like growth factor 1 (IGF-1) and the ratio of estrone to androstenedione (E:A).
The investigators found that while peak height velocity was greatest in girls who matured early and least in those who matured late, with earlier age at menarche related to greater peak height velocity, the pubertal growth spurt was longest in girls who matured early, and it was shortest in those who matured late. Higher IGF-1 levels were related to earlier age of peak height velocity, earlier age at menarche, greater peak height velocity, and taller adult height. A higher E:A ratio was linked with earlier age at menarche.
"Factors driving the association of earlier menarche and pubertal growth with breast cancer risk may be explained through a unifying concept relating higher IGF-1 concentrations, greater lifelong estrogen exposure, and longer pubertal growth period, with an expanded pubertal window of susceptibility," conclude the researchers, led by first author Frank M. Biro, MD, Professor of Pediatrics at the University of Cincinnati.
"We found important, dynamic relationships between the concentration of human growth factor and of other hormones at critical stages in growth that were not evident in short-term studies and cross-sectional studies," commented Dr. Biro. "This gives us a more accurate understanding of why early puberty poses a breast cancer risk and suggests ways for families to help their daughters reduce that risk."
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