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.

Screenings for colorectal cancer offer more than a chance for early treatment -- they offer the chance to avoid cancer completely. The disease usually starts with growths called polyps that can take a decade to turn cancerous. If polyps are found and removed, cancer can be avoided altogether. Yet many are avoiding the screening. And polyps that go undetected can turn to a cancer that can lurk silently in anyone -- especially during middle age and beyond. And black Americans are especially at risk.

Almost 42 million Americans over the age of 50 are not getting checked for colorectal cancer -- the nation's No. 2 cancer killer. Perhaps it's the financial burden that comes with the life-saving procedure. Now in five states, a government-funded program is offering free testing for the poor. But still, many will fall through the cracks in many states. And while Medicare pays for screenings, this federal program is for people 65 and older -- a long wait for someone at age 50 who needs the test but does not have insurance.

Perhaps it's the part of the body under study that steers people away. Perhaps it's the manner in which the test is performed -- a long, flexible tube is used to visually inspect the colon -- that turns heads in the wrong direction. While the financial burden is a valid deterrent, other worries or fears should be put to rest. The test is not all that bad, says one doctor who had a colonoscopy himself. The worst part of the whole experience may be the liquid mixture that is consumed prior to the test that cleans out the system -- minor discomfort really in the scope of the alternative. Cancer.

Colonocopies are recommended just once every 10 years. And nearly 60 percent of deaths from colorectal cancer can be prevented if each person over the age of 50 finds some way to make this screening happen. And if not this screening, there are other options -- like a fecal test that is done annually but is more more affordable and can be quite effective too. So consider your options. And make a choice.