Wouldn't it be great if we could receive full-body scans every year to check for early signs of cancer and other disease? Even if possible and affordable -- right now, scans cost about $900 -- it still wouldn't be such a great idea.

Full-body scans often result in false alarms. People with harmless abnormalities may end up facing more tests, more risks, and more worry in order to rule out illness. The scan itself can present health hazards too. It exposes patients to more radiation than a chest X-ray and could slightly increase the risk of cancer, especially for those scanned every year.

How do we know, then, if something has gone awry in our bodies? Well, we can do our self-exams -- breast exams, testicular exams, skin exams -- and we can report for annual check-ups. We can respond to symptoms we experience -- if headaches are bothersome and persistent, your doctor may prescribe a head scan -- and we can pursue tests and screening that we really need for cancer prevention and early detection. Here are just a few:

President Bush is keeping up with his colon cancer screenings. Good thing -- because five small growths were found and removed during his latest scan on Saturday.

The polyps found inside his large intestine were all less than one centimeter in size and did not appear suspicious. Still, they were sent to the National Naval Medical Center in Bethesda, Md., to be microscopically examined for signs of cancer. Polyps can turn into cancer, so finding them early is the best way to prevent the disease and improve the odds of surviving it. It takes 48 to 72 hours for pathology reports to come back, but the majority of polyps this size are unlikely to be cancerous.

Bush is no stranger to polyps. In 1998, after a similar scan, two polyps were found. In 1999, two more surfaced. And while none were found during his 2002 screening, he has become a prime candidate for regular examinations. For the general population, colonoscopy tests are recommended every 10 years.

David Foster was diagnosed with Advanced Renal Cell Carcinoma in April 2005. Translation: stage four kidney cancer and the sixth deadliest form of cancer. Not a great disease to acquire. Also not the end of the world. Just ask David who is busy working as a National Strategic Advisor in Augusta, Georgia, headlining within the independent magazine community, hanging out with dog Gracie, and documenting his journey in a blog he calls David Foster's Kicking Kidney Cancer's Arse.

He's no wimp, this guy. Just read his June 23 post, titled May kill me, but it ain't gonna beat me. He didn't let that hard-nosed kid Jerry whip him when he was eight -- he smacked him so hard in the lunchroom, Jerry was left stumbling and bleeding -- and he won't let cancer bully him either. Still, David admits: he is sick. He explains it all in a post he calls Mr. Foster, are you really sick?

David got an e-mail one day. It read, Mr. Foster, are you really sick? I read your blog and you don't sound sick.

Ever since revealing her breast cancer had recurred, there has been speculation about a spread from Elizabeth Edwards' rib -- the initial metastasis -- to other spots in her body.

Last night, on the CBS news program 60 Minutes, Edwards told Katie Couric that a hot spot has been detected in her right hip. But doctors believe it is too small to pose a new health risk, she reports.

"There are a couple of hot spots, on the bone scan, in my right hip, for example," she said. "And one of the questions is whether or not to do radiation to reduce the size of that -- of the cancer in that location -- and for fear that it might weaken my bone and that I might break my hip. But their consensus was that it was too small an area for that to be a risk."

In addition to discussion about the cancer itself, Edwards and her husband John defended their decision to stick with the presidential race. Edwards said she just cannot deny her husband the chance to be president.

"That would be my legacy, wouldn't it, Katie?" Edwards said to Couric. "That I'd taken out this fine man from -- from the possibility of -- of giving a great service. I mean, I don't want that to be my legacy."

White House press secretary and colon cancer survivor Tony Snow asks the public to refrain from jumping to conclusions regarding the surgery he will have on Monday to remove a growth from his lower abdomen.

Blood tests and a CAT scan of the growth show no presence of cancer, he reports. But still, he and doctors are proceeding cautiously due to his history.

Snow, a former Fox News radio and television talk show host, was diagnosed with cancer two years ago, when he was a commentator at Fox. Two months after surgery, he returned to the air and then became White House press secretary in April 2006.

Snow's plan is to be back behind the podium a few weeks after surgery, when he has a better idea of what it is he's dealing with.

Radioactive cancer patients attending this weekend's Super Bowl in Miami could be in for an alarming experience when they pass through radiation detectors designed to signal the presence of dirty bombs. Such cancer patients -- who have received treatment using radioisotopes and still may have tiny amounts of radioactive material in their bodies -- may want to come armed with letters from their doctors explaining their precarious set of circumstances.

The use of radioisotopes in medicine is growing -- and so is the use of radiation detectors in our security-conscious nation, which means patients are triggering alarms when they are not even aware they are being scanned, doctors and security officials say.

Nearly 60,000 people a day in the United States undergo treatment or tests that leave traces of radioactive material in their bodies, according to the Society of Nuclear Medicine. These traces are not enough to hurt anyone, but they are enough to trigger radiation alarms for up to three months.

Radioisotopes are commonly used to diagnose and treat certain cancers and thyroid disorders, to analyze heart function, and to scan bones and lungs. And many doctors already know to equip their patients with travel cards because of the problems they can encounter in public places.

Nearly 20 million nuclear medical procedures were performed in the United States in 2005 -- up 15 percent from 2001. Clearly, the number of people who could be mistaken for terrorists is quite large. So if you are one of these people -- with the power to create a buzz in a public setting -- get your papers in order so you can quickly confirm your identity as nothing more than a cancer patient.

Positron emission tomography (PET) can measure metabolic activity of tissue. Cancer cells tend to have a higher metabolism than normal tissue, which can be determined on PET for more accurate detection of cancer.

Using the PET scan after diagnoses of breast cancer to check lymph nodes for cancer was looked at in a study that was published in the Archives of Surgery. What the study found out is that the PET scan can detect 60 percent of patients with positive nodes. These patients that know they have positive nodes might be able to start therapy and avoid the axillary dissection or the sentinel node biopsy. These surgical procedures can often have side effects. By avoiding these surgeries a patient that knows they have positive lymph nodes won't have to wait for surgery and extra time to heal to start chemotherapy or other treatments.

If a patient has a negative PET scan showing no cancer in the lymph nodes the axillary dissection or the sentinel node biopsy should be performed since the PET can only pick up 60 percent of patients cancer in the lymph nodes. The patients could still have microscopic cancer cells that the PET can't pick up so in this case surgery is needed.

Getting accurate information on whether or not the cancer was confined to the breast has a big impact on the treatment plan.

According to researchers, a new blood test can accurately detect early stage non-small-cell lung cancer, the most common type of lung cancer, with 90 percent accuracy. This advancement in lung cancer diagnosis has the potential to eliminate the sometimes inaccurate test results reported with CT scans. After a CT scan, biopsies are often required to confirm the presence of lung cancer. The accuracy of the blood test reduces the number of biopsies done in the need to confirm detection of lung cancer. Another benefit of the blood test is that it can detect non-small-cell lung cancer years before traditional X-ray tests can.

The blood test to detect non-small-cell lung cancer is licensed to 20/20 GeneSystems. Additional clinical studies will be done to confirm the accuracy of the blood test, and if it proves to be as accurate as the initial studies have indicated, this blood test will become the first blood test to predict cancer since the introduction of a prostate specific antigen blood test, PSA, to detect prostate cancer.

This research is published in the Journal of Thoracic Oncology.

Whoever stumbled across this discovery is a genius! First let me say there is nothing that will knock the breath right out of you than being told a test for cancer has come back positive. False-positive results are determined when the second follow-up test reveals the first test is an error in diagnosis. I am certain the first reaction is relief -- and then a sort of aggravation that you had to be put through the harrowing emotions of a cancer diagnosis in the first place.

False-positives can happen for a number of reasons, but one of them involves body heat generated by brown adipose tissue, or brown fat, which can mimic cancer during a PET/CT scan. The current solution is the use of valium and beta blockers during the scan, and studies have shown it reduces reading error by 30 percent. However -- and here is where the whoever thought to do this is a genius comes into play -- the simple use of a warm blanket is more than twice as effective as the administration of drugs in preventing the uptake of tracer by brown fat in the body. According to the researchers, everyone has brown fat, but it is more common in slender women.