During a decade in national politics, Claire McCaskill has been a trailblazer several times. In 2006, she was the first woman elected to the Senate from Missouri. In 2008, the first senator to back Barack Obama for president. In 2012, the biggest upset winner among the many Democratic incumbents challenged by tea party Republicans. And almost three years ago, the first in Congress to endorse Hillary Clinton well before she started this presidential campaign.
This week McCaskill stood apart again, becoming the first senator to announce she has breast cancer.