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.

I have heard the term chemobrain many times -- even here at The Cancer Blog when Dalene wrote about it. And I've started using the terminology myself -- to explain my new-found odd behavior. Like when I put a carton of ice cream in the refrigerator with no recollection of it. And when I took a cap off a pen, couldn't find it, and discovered it on top of an egg carton in the refrigerator. I don't think this is a refrigerator theme -- just a coincidence -- because I've also lost a clipboard at work, forgotten to hand a guest her glass of water immediately after I prepared it, lost library books and movies, and failed to remember responsibilities time and time again. This may seem like minor forgetfulness -- this is what my oncologist believes may be at work -- but for me, this is odd. I have always had a good memory, have always delivered on my promises, and have never felt as scattered as I do now. So I call it chemobrain -- a good excuse, I figure -- and am now trying to determine what exactly this word means.

My oncologist tells me he doesn't really like this term. He thinks it puts a negative spin on regular functioning. He believes those of us who have experienced chemotherapy look more closely at our post-chemo behavior and may interpret quirky stuff as more serious than it is. It probably existed before chemotherapy, he says. But now, we are more sensitive to it and find chemotherapy a good explanation. He may be right. But for me, something in my head has definitely been altered.

One patient advocate for Hurricane Voices: A Breast Cancer Foundation believes that something doesn't have to be scientifically proven to exist. And while chemobrain may not be completely proven, there are still studies that support its existence -- which manifests itself through aging-type memory problems, forgetfulness, distraction, and loss of the ability to calculate quickly. Some studies show that 20 to 30 percent of women who undergo chemotherapy for breast cancer, and some who receive similar treatment for lymphoma, score lower than average on mental function tests for as long as 10 years after chemotherapy. ''There's enough data now to at least know it's a real effect,'' said Dr. Ian F. Tannock, a psychiatrist who has studied this issue at Princess Margaret Hospital in Toronto. Some suggest that typical aging may be at fault -- and for premenopausal women who may be rushed into menopause, this effect may be due to hormonal issues. Regardless, it seems to stem from chemotherapy -- somehow. And somehow, this topic needs more attention, more research, and maybe a more positive name.