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Missouri Democrat Sen. Claire McCaskill announced on her social media accounts that she has breast cancer on Monday, a disease she says was detected through a routine mammogram.

I very recently learned that I have breast cancer... - https://t.co/VYOi5pohqP — Claire McCaskill (@clairecmc) February 22, 2016

"I very recently learned that I have breast cancer. It was detected through a regular mammogram," she wrote on her Tumblr account. "It’s a little scary, but my prognosis is good and I expect a full recovery."

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McCaskill, 62, said that she would spend the next three weeks in St. Louis receiving treatment.

She directed readers to her website for a record on how she would have voted on issues that may come before the Senate during her absence and plans on submitting questions for hearings she may miss.