Elizabeth Edwards has been told the metastatic cancer found in her bones is considered stage four. And it's treatable. But not curable.

Tricky stuff -- all this cancer terminology -- and a little hard to fully comprehend.

I saw Sheryl Crow talking with Maria Shriver and Dr. Susan Love on Larry's King's CNN program the other night. Crow says her breast cancer was curable -- it was teeny tiny and had not spread and required a lumpectomy and radiation, but not chemotherapy. "I'm the walking poster child for early detection," she said. Her cancer was caught and treated swiftly. She is cured. Theoretically.

Can Crow's cancer still return? Yep.

We just aren't sure at the time of one cancer discovery if these deadly cells have drifted away from the main site and will later show up elsewhere, explained Dr. Love. All predictions would have Crow living a long life free of cancer. But they may have had Edwards in the same boat just two years ago when she was first diagnosed with breast cancer.

So now Edwards' cancer is not curable. It is treatable. And this is a bit easier to understand. Her cancer will never go away. But doctors can keep it at bay. And Love says they can even make it better. But there is no cure for what Edwards has. So she will live with cancer for the rest of her life.

I guess curable means: the cancer is gone and we hope it never comes back. And treatable means: the cancer is not gone and will never be gone but we will treat it for as long as we can.

I think I get it.