A newly releasted report on the incidence of breast cancer appeared in JAMA today indicating that the incidence of metastatic breast cancer in women 25- to 39-years of age has almost doubled from 1976 to 2009, from 1.53 to 2.90 per 100,000 women, or a growth rate of over 2% per year. No other age group had a similar increase, nor did non-metastatic cancer rise even in this age group. The increase was particularly marked among women with estrogen-receptor positive types of cancer.
Estrogen exposure from various sources has surely increased over the last three decades, and might contribute to this statistic. Our own obese tissue secretes estrogen and synthetic chemicals in the environment, from plastics, to pesticides, to cosmetics and house cleaning agents, all can mimic estrogen's effects in the bloodstream.