Edie Littlefield Sundby may not have thought she'd ignite a national debate when the stage-4 cancer survivor asked us to publish her Monday op-ed on losing her oncologist due to the Affordable Care Act. But she certainly has, and it's important to understand why. Mrs. Sundby and millions like her must be denied their medical choices if ObamaCare is going to work as its liberal planners intend.

Mrs. Sundby's seven years of gallbladder cancer treatment have been underwritten by a policy known as preferred provider organization...