WASHINGTON — Nearly half the people who need potentially lifesaving checks for the nation's No. 2 cancer killer — colorectal cancer — miss them, despite years of public efforts to make colon screening as widespread as tests for breast and prostate cancer.

But what if you opened your mailbox one day to find an at-home test kit, no doctor's appointment needed?

The dreaded colonoscopy might get the most attention, but a cheap, old-fashioned stool test works, too — and when California health care giant Kaiser Permanente started mailing those tests to patients due for a colon check, its screening rates jumped well above the national average.

Now specialists are looking to Kaiser and the Veterans Affairs health system, another program that stresses stool-tests, for clues to what might encourage more people to get screened for a cancer that can be prevented, not just treated, if only early signs of trouble are spotted in time.

"By overselling and overpromising colonoscopies, we've put up barriers for people" to get any type of screening, said Dr. T.R. Levin, Kaiser Permanente's colorectal cancer screening chief in northern California.

Everyone is supposed to get screened for colorectal cancer starting at age 50, but U.S. data shows just 55 percent do. That's better than a decade ago when screening rates hovered below 30 percent, and both new cases and deaths have dropped as a result.

But about 150,000 people still are diagnosed with colorectal cancer each year, and nearly 50,000 die. The Centers for Disease Control and Prevention said proper screening could eliminate many new cases, because regular colon checks can remove precancerous growths called polyps before the cancer has time to form.

Colonoscopies — where doctors use a long, flexible tube to visually inspect the colon — now account for 80 percent of all screening, a panel of specialists convened by the National Institutes of Health reported this month.

The $20 stool test — usually handed over by a doctor, performed at home and then mailed to a lab — is considered as effective if properly used once a year. But its use has dropped as colonoscopies took center stage.

Many doctors recommend colonoscopies as "one-stop shopping: You get screened and can get treated with one intervention," said NIH panel member Dr. Lawrence Friedman of Harvard Medical School and Tufts University.

Sedation means it doesn't hurt, although it requires a day of bowel-cleansing preparation and can exceed $1,000. But colonoscopies allow removal of polyps on sight. If no problems are found, they're only required once a decade. They're also the required next step when the stool test or other screenings signal a possible problem. Other options: sigmoidoscopy, an exam of the lower colon only, and the new virtual colonoscopy, a new X-ray exam offered in only limited places.

The NIH panel concluded people should pick the screening option best for their own needs and comfort, but it urged eliminating financial barriers. Both out-of-pocket costs and access to a regular health provider to advise about each option's pros and cons are hurdles.

Indeed, researchers at the Fred Hutchinson Cancer Center last week reported racial disparities in colon cancer are widening, suggesting unequal improvements in screening access. In 1992, blacks were 60 percent more likely than white to be diagnosed with late-stage colorectal cancer; by 2004, that likelihood had doubled.