The continued decline in new cases of colorectal cancer represents only a tantalizing peek at what could be achieved if more people took advantage of colon cancer screening, experts say.
A concentrated push to increase screening to 80%—the rate now seen with mammography—could cut by half the 52,000 colorectal cancer deaths expected this year, said Dr. Bernard Levin, vice president for cancer prevention and population science at the M.D. Anderson Cancer Center, Houston.
National surveys show that each year, about half of U.S. citizens eligible for screening undergo the test. But despite the steady decreases in new colon cancer diagnoses and mortality, a 50% screening rate just isn't good enough.
“Although it's high, it's not at the optimal level,” Dr. Levin said in an interview. “What is outstandingly obvious is that we could do so much more.”
Dr. Sidney Winawer, a gastroenterologist who holds the Paul Sherlock Chair at Memorial Sloan Kettering Cancer Center, New York, agreed.
“We don't have anything in colorectal cancer like the educational outreach that we see for breast cancer screening. They get their message out consistently, repeatedly, and to many different groups. That's what we need to do—not just talk about screening once a year in March [National Colorectal Cancer Awareness Month].”
The American Cancer Society's latest report on U.S. trends says about 112,000 new cases of colorectal cancer will be diagnosed in 2007. That's a 2% decrease from the 2004 report, and a continuation of the decline since 1985. But colorectal cancer is still a killer, ranking third in both prevalence and mortality in men as well as women, the report says.
The problem of education is one that must be “attacked on multiple fronts,” said Dr. Winawer, who is also the director of the World Health Organization's Collaborating Center for the Prevention of Colorectal Cancer. “Patient education is only one part of our task. We also need to educate providers—gastroenterologists, primary care physicians, nurses, and health maintenance organizations.”
He envisions a message with three components: family history, gender equality, and minimizing fear. “We have to emphasize that the risks are equal for men and women. … It is an equal-opportunity killer.”
People with a family history of polyps or colorectal cancer are at significantly increased risk of developing the disease; they need to understand that screening is even more important for them, and should begin at a younger age.
“And we simply have to address the fear component of this,” Dr. Winawer said. “People shouldn't be afraid to be screened. The tests are much more comfortable than they were, sedation is much better, we are more experienced, and the instruments are much better.” In addition, he said, most patients don't need to be afraid of what the scope might see, since most colonoscopy findings are easily removed polyps or very early, highly curable cancers.
Because screening picks up these early lesions, it has also contributed to the significant decrease in colorectal cancer mortality noted in the ACS report—about 5,000 fewer deaths are expected this year than were expected according to the 2004 report.
But advances in treatment also play a very strong role here, said Dr. Alfred Neugut, head of cancer prevention and control at Herbert Irving Comprehensive Cancer Center, New York.
“Colorectal cancer has seen some huge advances in treatment in the last few years, some of the most dramatic treatment changes seen in any cancer. We went from having just one active drug, 5-fluorouracil, to having six or seven.”
Advances in adjuvant therapy for regionally advanced colon cancer have also had a significant impact on mortality. “There has also been an improvement, although less dramatic, in treating metastatic colon cancer,” Dr. Neugut said.
Screening and treatment are undoubtedly the biggest contributors to the steady decrease in colorectal cancer, the physicians said. But other factors are at work, exerting a smaller effect or one that is difficult to extrapolate. “Lifestyle changes have probably played a part,” he said. “People are more health conscious with regard to diet and exercising.”
Hormone therapy in postmenopausal women might also be exerting a small protective effect, Dr. Levin added. “And there may be some small effect of the very widespread use of nonsteroidal anti-inflammatories, which are known to reduce both colon polyps and cancer.”
Still, the experts agreed, screening is the area that deserves the most emphasis. Advances in the comfort and accuracy of screening will combine to make it a more acceptable option for more people, they predicted.
“We are in an exciting time with regard to developing options for screening,” Dr. Winawer said. “Soon we're going to see better stool screening methods, including a DNA mutation test and an immunochemical test, both of which may be much more accurate than fecal occult blood.”