After decades of debate and inconclusive findings, a major new study has shown that a yearly test can significantly reduce deaths from colon and rectal cancer, the second leading cause of cancer deaths among Americans.
In the 13-year study, those in a group randomly chosen to undergo annual tests for blood in their stools experienced 33 percent fewer deaths from cancers of the colon and rectum than did those in a similar group who were not offered the test.
The study, conducted among 46,551 Minnesota residents, showed that the screening test could detect colorectal cancer at an early and curable stage, before symptoms were apparent. The test also turned up many adenomatous polyps, lesions in the bowel that are considered precancerous.
The life-saving benefit was found even though only 46 percent of the screened group took all 11 of the offered tests.
One drawback to the findings, however, is that because fecal blood can be caused by benign conditions, people with positive results on the screening test have to undergo costly follow-up exams to determine whether they actually have cancer.
The study, longer and larger than any previously undertaken, is being published today in the New England Journal of Medicine.
"We think this is quite an astounding result in terms of its impact zTC on this disease," the director of the study, Dr. Jack S. Mandel, said yesterday in an interview.
The findings suggest that if all Americans over age 50 took the test every year, more than a quarter of a million lives would be saved over the next 13 years, based on current incidence and death rates from colorectal cancer.
The American Cancer Society estimates that 152,000 new cases of this cancer will be diagnosed this year, and 57,000 Americans, the vast majority of them over 50, will die of the disease, which ranks behind lung cancer as a cause of death among Americans.
Dr. Sidney J. Winawer, chief of the gastroenterology and nutrition service at the Memorial Sloan-Kettering Cancer Center in New York, said in an interview that according to the findings, one in 10 people who are not considered at high risk for colon cancer will have a positive stool test, "and in this group you'll find 92 percent of the colon cancers."
Dr. Winawer, who wrote an editorial praising the new study, said it showed "for the first time a significant decline in the death rate as a result of testing. . ."
The cancer society currently recommends that people over age 50 should get the test, which costs only $20 to $40, once a year.
But the encouraging results, while vindicating the cancer society's assertion that the simple test for fecal occult, or hidden, blood can save lives, is likely to spur a further debate: Can a health-care system in economic straits afford the millions of expensive follow-up tests that would be needed to determine which of the nearly 10 percent of people with positive results on the screening test actually have cancer or premalignant polyps?
In the new study, only one in three people whose screening tests showed blood in the stool were subsequently found to have cancer or precancerous polyps. But all those with positive test results had to undergo a costly colonoscopy, a procedure in which a flexible scope is used to examine the entire five feet of the lower bowel.
When performed in a doctor's office, a colonoscopy typically costs $700 to $900. But hospitals, where some colonoscopies are performed, may charge two to three times those prices.
If all 60 million Americans over 50 had a fecal occult blood test each year, the new study suggests that about 6 million of them would need the costly follow-up tests.