Cannon's 25-year-old daughter was first diagnosed with cancer 3 1/2 years ago, but she responded well to the surgery and immuno-therapy and had been healthy since. On Friday, scans detected that the tumor had returned and metastasized in her body.

Cannon, who is running for a fifth House term, said he will curtail his campaign schedule and miss some votes in Congress in order to be with his family. Cannon said his constituents value families and will understand his occasional absence.

“This is one of those [cancers] that's very aggressive, and if we can curtail the growth then that will determine” how much time he misses, Cannon said. “It depends on what votes come up and when, and also if I'm needed on votes - and primarily it will turn on coming up with a treatment routine.”

He said it will take a few weeks to meet with the various doctors and develop a treatment regimen. The form of cancer she suffers from is exceptionally rare and spreads quickly. The only treatment for it is to try to surgically remove the tumor and boost the patient's immune system.

It's not clear what causes the cancer, although some studies suggest an exposure to herbicide may play a role. Cannon said there is also some family history of cancer. His father suffered from leukemia and prostate cancer.

The news of his daughter's setback has been difficult, Cannon said.

“This is hard. On a positive note, the world has changed a lot in the last three or four years,” he said. “There's a lot more information available and while I do think we need to do a better job with cancer in America there is a lot more information than there was a few years ago.”