The higher risk for breast cancer in obese women after menopause is thought to result mainly from chronic exposure of

Estrogen ...

Answer;

Estrogen

The higher risk for breast cancer in obese women after menopause is thought to result mainly from chronic exposure of Estrogen.

Explanation;

Being overweight is associated with increased risk of breast cancer, especially for women after menopause.

Fat tissue is the body's main source of estrogen after menopause, when the ovaries stop producing the hormone.