Presidential candidate John Edwards and his wife Elizabeth will appear tonight on 60 Minutes where they will publicly discuss with Katie Couric Elizabeth's newest cancer diagnosis and their decision to continue on in the presidential race.

Elizabeth, 57 and first diagnosed with breast cancer in November 2004, shared Thursday that her cancer has returned, this time in her bones. Considered stage four and treatable -- but not curable -- her cancer has generated much discussion and awareness about the workings of this life-threatening disease.

To view a clip from tonight's news program, airing at 7:00 PM ET/PT, click here.

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.

Elizabeth Edwards, wife of Democratic presidential candidate John Edwards, has had many routine medical follow-ups since her 2004 breast cancer diagnosis. And all of them -- until just a few days ago -- resulted in what is generally termed a clean bill of health.

The term doesn't always come with a sense of relief for those of us surviving breast cancer -- or any cancer for that matter -- because it only really defines what our bodies are telling us at one specific moment. There are no magic blood tests, no special body scans, no conclusive ways of determining whether or not cancerous cells have gone astray and will one day surface again.

I asked my oncologist after my first six-month follow-up how he would know if my cancer returns. He told me it's really up to me to determine whether it comes back. It's up to me to get mammograms and ultrasounds and MRIs. It's up to me to report any symptoms and suspicions. It's up to me to track my general well-being so that it will be clear when something feels not-so-right. If I have a persistent cough or headaches that won't subside, my doctor will take action with X-rays and scans and tests. But as long as I feel fine and nothing troubling presents itself, then I remain in the clean-bill-of-health club.

Edwards no longer has a clean bill of health. But she is determined to use her newest diagnosis -- stage four metastatic cancer of the bones, considered treatable but not curable -- to work toward the best health she can acquire for as long as she can hold onto it. And that is about as good as any of us can do.

Boise State basketball player Coby Karl, son of Denver Nuggets coach George Karl, had surgery 13 months ago to remove his thyroid after he was diagnosed with papillary carcinoma, a form of treatable cancer. And while Karl received chemotherapy to kill off any lingering cancer cells, he must undergo cancer surgery once again.

Karl, who plans to play in the NABC All-Star game in Atlanta on March 31, will return to Boise on April 2 for surgery to remove cancerous lymph nodes.

The lymph node cancer was identified in January, but Karl, 23, kept his condition private until his team lost to New Mexico State in the Western Athletic Conference tournament semifinals. This ended the Broncos' season. And now begins Karl's second go-round with cancer.

You may remember Karl as one of last year's NBA draft hopefuls. He worked out for three teams, including his dad's team, but eventually withdrew his name from the draft and returned to Boise State for his senior year.

Virginia Congresswoman Jo Ann Davis announced this week that she has been diagnosed with breast cancer -- again. Her first bout with the disease began in October 2005. Her recurrence was spotted last month during her recovery from an unrelated medical procedure.

Davis, who received both a mastectomy and chemotherapy treatment during her first battle with breast cancer, knows she will conquer cancer for a second time.

"This cancer is treatable," Davis says. "I have just begun chemotherapy and I am very confident of a full recovery. I was able to beat this disease before, and I will beat it once again. I again plan on working throughout this process, and I once again believe that this experience will help me in serving Virginia's First Congressional District."

Davis, who is at home recovering from a ruptured ureter, will return to Washington this month.

It's March. And that means it's the national month for Brain Injury Awareness, Endometriosis Awareness, Nutrition Awareness, Eye Health and Safety Awareness, Multiple Sclerosis Awareness, Sleep Awareness, Problem Gambling Awareness and my favorite, for the purposes of The Cancer Blog -- Colorectal Cancer Awareness.

Colorectal cancer -- cancer of the colon or rectum -- is a disease that affects both men and women and is preventable nearly 90 percent of the time.

Starting at age 50, men at women at average risk for the disease should get screened. Those with increased risk, like African-Americans who typically develop colorectal cancer at younger ages, should be screened even earlier.

Screening -- by way of fecal occult blood test (FOBT), flexible sigmoidoscopy, and colonoscopy -- is critical because colorectal cancer often occurs with no symptoms. Symptoms do sometimes present themselves in the later stages of the disease and include rectal bleeding, bright red blood in or on the stool, change in bowel habits, stools that are narrower than usual, general stomach discomfort, diarrhea, constipation, frequent gas pains, unexplained weight loss, constant fatigue, and vomiting. Persistence of any of these symptoms for more than two weeks warrant an immediate visit with a health professional.

Treatment for this disease, which strikes about 153,000 people and causes about 52,000 deaths each year, includes surgery, radiation, and chemotherapy.

In the spirit of this National Colorectal Awareness Month, experts recommend remembering these important points:

• Colorectal cancer can be prevented.
• Screening for the disease can identify polyps -- grape-sized growths in the colon and/or rectum -- that can be removed to prevent cancer from developing.
• The magic age for screening is 50 -- unless you have an increased risk for the disease.
• Colorectal cancer is treatable.
• Regardless of your age, know the risk factors, know the symptoms, and know your family history.
• Talk with your health professional about colorectal cancer and your own risk for the disease.