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:

I hate it when I fit the mold for some not-so-great research finding. Like the recent news about how women with early-stage cancer of the left breast (that's me) who are treated with radiation following lumpectomy (me again) face an increased risk of developing radiation-related coronary damage.

OK, so the benefits of radiation therapy still outweigh the risks. Still, when radiation is applied to the breast on the same side as the heart, there are worries. I knew about these concerns. My radiation oncologist addressed them prior to my treatment. Hearing that an actual, important, convincing study confirms what I already knew may be a side effect, though, makes my heart race a little bit more.

There were 961 women with stage I and II breast cancer who were followed in this study. Well, the arteries in their hearts were studied anyway. Some had left-sided breast cancer; the others had right-sided. Some 12 years after radiation, 46 of the 485 left-sided women and 36 of the right-sided group needed cardiac stress testing. Among those tested, 59 percent in the left-sided group had abnormalities. Only 8 percent in the right-sided group showed problems.

It seems screening for lung cancer doesn't save lives and it doesn't prevent advanced disease. But it does lead to potentially unnecessary and harmful treatment.

This isn't the final word on the use of CT scans to screen smokers and former smokers for the disease. But right now, the hope some experts had for the special X-rays to detect tiny lung abnormalities has been diminished by a large study that is still in the works. And until conclusive evidence says the screening is useful, the American Cancer Society will not endorse the test.

While CT screening did increase diagnosis and treatment -- those screened were three times more likely to be diagnosed with lung cancer and 10 times more likely to have lung surgery than predicted -- study co-author Dr. Peter Bach of Memorial Sloan-Kettering Cancer Center in New York says, "We don't see a trace of evidence that a single life was saved, that a single case of advanced cancer was avoided."

And because CT scanning led to more biopsies and surgeries, patients were put at risk for complications such as lung puncture, bleeding, and infection, according to Bach, whose work is published in the Journal of the American Medical Association.

"Getting screened for lung cancer with CT scanning is not only unproven, it's potentially a risky endeavor," he said.

Until an effective screening tool emerges -- possibly still years away -- experts say there is one surefire way to protect yourself from lung cancer. Stop smoking.

Besides preventing birth defects in the brain and spine and other congenital abnormalities, the folic acid found in prenatal multivitamins has now been shown to prevent cancer in children whose mothers take the vitamins during pregnancy.

A new Canadian study, appearing online in the journal Clinical Pharmacology & Therapeutics, estimates prenatal multivitamin supplements can save hundreds of children each year in Canada -- where only 40 to 50 percent of women take prenatal vitamins -- from developing leukemia, brain tumors, or neuroblastoma. And the vitamins may prevent 900 cases of pediatric leukemia and more than 300 brain tumor cases annually in the United States.

It's not clear which vitamins or minerals, and in what amounts, could be protecting babies from cancer, but it's possible folic acid -- critical for cellular function -- may be acting alone.

One thing is certain, says lead investigator Dr. Gideon Koren -- this is one inexpensive way to prevent cancer.

A colonoscopy camera lets the physician check for abnormalities inside the colon. These can include cancerous or precancerous growths. The doctor guides a flexible scope though the colon, that can take about seven minutes, he then spends on average another six minutes withdrawing the scope evaluating inside of the colon.

The New England Journal of Medicine published a study that found colonoscopies that took a longer time to complete found more abnormal growths. Faster testing was shown to miss some abnormalities. Doctors who spent more than six minutes withdrawing the colonoscopy tube found more abnormal growths than those who withdrew it in less than six minutes.

The study did not have a conclusive answer as to exactly long physicians should spend withdrawing the tube. Other experts say to keep it in the range of six to ten minutes.

I know this is the last thing you want to say to your physician-- "Can you keep that up there a bit longer please?', but it might just save your life.

There is no major test or screening tool or exam that reveals the definite presence of cancer in the body. There are mammograms that can detect suspicious masses in the breast and there is a blood test that might raise concerns about the health of ovaries and there are various x-rays and scans that allow doctors to peek into the intricacies of the human body -- and some tests, like the mammogram clearly do save lives -- but some tests that seem harmless can damage the psyche while accomplishing little else.

I asked my oncologist how he would know if my breast cancer returns. He said I will receive regular mammograms and ultrasounds of my breasts. And he will perform in-office exams every few months. He will complete a breast exam and will feel my neck for enlarged lymph nodes. He will listen to my lungs and feel my stomach. But largely, he will rely on me to report symptoms and signs and complaints -- because these are the true indicators that something is amiss.

I imagined myself getting a whole host of tests on my whole body to rule out that cancer is invading every part of me. But this won't happen without reason -- because some tools, like imaging tests, may detect noncancerous abnormalities and false positives that lead to unnecessary psychological stress and tests -- and sometimes even surgery. So if I develop a persistent cough that can't be controlled, perhaps my oncologist will order a chest x-ray. If headaches begin to plague me and relief is not in sight, then perhaps a scan of my head will be in order. But as long as I feel well, the assumption is that I am well. It's better for my soul this way -- to live life without the constant worry that cancer will return. And it's a whole lot more cost effective too.