FORT LAUDERDALE, Fla--Because colon cancer develops in a stepwise progression that occurs over 10 to 15 years, physicians have a "tremendous window of opportunity for prevention," Sidney Winawer, MD, of Memorial Sloan-Kettering Cancer Center, said in a presentation at the second annual Industries' Coalition Against Cancer (ICAC) conference. He believes that colorectal cancer screening is "no longer controversial," based on available data.
For companies watching the bottom line, such screening programs, if carefully planned, should also be cost effective, a representative of Eli Lilly & Co. said at a session on screening programs currently under development.
The goal of colorectal cancer screening is to prevent cancer by removing polyps, rather than to detect cancer in the early stages, Dr. Winawer said. He and his colleagues recently published the results of the National Polyp Study, which has more than 8,000 person-years of follow-up in a cohort of 1,400 individuals.
"We expected to see a large number of colon cancers in this cohort after their polyps were removed, but we observed only five, and none of these were symptomatic. They were all discovered on a follow-up examination as a malignant polyp in the very early stage." he said.
For asymptomatic individuals at average risk, the American Cancer Society and the WHO Colon Cancer Prevention Program at Memorial Sloan-Kettering, which Dr. Winawer heads, recommend, starting at age 50, a flexible sigmoidoscopy every 3 to 5 years, and annual fecal occult blood testing such as Hemoccult.
"The two tests work well together," he said. "The Hemoccult test examines the upper bowel, and the flexible sigmoidoscope examines the lower bowel."
For high-risk individuals, including those with a known genetic factor or family history, the screening strategy changes to one involving colonoscopy and beginning at an earlier age, he said.