That's because the pills impact hormone-sensitive tissue, which ALSO means that, conversely, the Pill --- like abrtion --- increases the risk of breast cancer, because the mammary glands are hormone-sensitive.
They'll never admit that, because the liability lawsuits would bankrupt the whole industry.
My previous post was really only to say that RE hormone changes and migraines, pills are only one small part of a much larger picture.
However, taking hormones orally is not a good idea and can lead to many bad things including cancer. Fake hormones are not good for us. If you need hormones they should be taken any way but oral.