'Male' Hormone Tied to Early Puberty in Girls
The researchers found that girls whose genetic makeup caused them to produce higher levels of a liver enzyme that breaks down testosterone, called CYP3A4, tended to start puberty earlier. These findings suggest that girls with relatively low levels of testosterone might experience early puberty and hence a higher risk of breast cancer.
"Because the early onset of puberty is a risk factor for breast cancer, it won't be surprising if studies of this genetic variance and breast cancer also find it to be a risk factor," Kadlubar said.
Next, Kadlubar and his team will look at how this same genetic variation affects the onset of puberty in young boys. He expects to find an opposite relationship. That is, boys with the highest levels of testosterone in their bodies should start puberty soonest.