However, radiologists who do the actual mammography screenings have long known hormone use can change breast tissue.

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"Based on our study, we do not recommend women change their hormone use, " said Laya.

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We have to change their skulls, their metabolism, their hormone interactions, the structure of their limbs, and everything else that is affected in the process of accomplishing those goals.

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"To specifically overcome resistance to hormone treatment that's sort of a paradigm change, " said Gabriel Hortobagyi, head of breast oncology at MD Anderson Cancer Center in Houston and lead author of Bolero-2.

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In fact, Hunt said, mixed martial arts guidelines don't require a sex-change surgery, but they do require two years of hormone therapy for transgender fighters.

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