Scientech Logo


...a club for people who never stop learning...

The Scientech Club provides a forum for weekly presentations and discussions in the fields of science and technology and other topics for the enlightenment of its membership.

Regular, one-hour Meetings are, with the exception of holidays, held every Monday at noon at The Northside Knights of Columbus, 2100 East 71st Street, Indianapolis. Club Members, as well as the general public, may attend our Regular Meetings for a nominal contribution to pay for the facility. For those who wish, a buffet lunch may be enjoyed before the meeting. Occasionally, instead of a presentation, members and their guests may take a tour to a place of interest, such as a plant or historical site.

The Scientech Club is associated with an outstanding local charitable Foundation, The Scientech Club Foundation, established by Scientech members to promote science education. Information about the foundation may be found under the heading Foundations above.

Vol 92 No 24 - June 29, 2015

Colon Cancer Detection

Presented By: Joe Henderson, MD, Gastroenterologist, Indianapolis


Dr. Joe Henderson

Today's talk was given By Dr. Joseph Henderson, a Gastroenterologist from Community Hospital here in Indianapolis. The talk was primarily about colon cancer screening in asymptomatic people with average risk for colon cancer. The discussion largely does not apply to persons with other forms of bowel disease, genetic predispositions, or a prior diagnosis of colon cancer or precancerous colon polyps.

Dr. Henderson's first point was that cancer of the colon is the 3rd most common type of cancer in both men and women. While less common than breast or prostate cancer, it is the 2nd leading cause of cancer deaths. In 2015, 132,700 new cases of colorectal cancer(CRC)will be diagnosed. 49,700 deaths will be attributable to these cases. Predisposing to colon cancer is age over 50, first degree relative with colon cancer diagnosed before the age of 60, adenomas, and Sessile Serrated Polyps. There are also rare genetic cases such as Lynch syndrome, and familial adenomatous polyposis syndrome. Race, obesity, gender, alcohol, high red meat consumption, and smoking increase the risk to some extent.

Dr. Henderson then stressed the importance of early detection of cancer and the predisposing polyps. He discussed several screening options. These include the detection of blood in the stool (fecal occult blood test - FOBT) by any of several methods, and directly visualizing the cancer and predisposing polyps by colonoscopy, sigmoidoscopy, or CT colonography. While not perfect, he feels that colonoscopy is the gold standard detecting 90 to 95% of colon lesions. If the cecum cannot be reached, then CT colonography might be used as an adjunct.

Important: a single stool test for occult blood in the Doctor's office is not sufficient. A valid test requires individual specimens from 3 different stool samples for the Hemoccult Sensa test.

Important: do not retest the stool to verify a positive test. Go straight to colonoscopy if a stool sample is positive for blood.

Important: colonoscopy requires an experienced endoscopist, a very clean colon, and visualization of the entire colon from the anus to the cecal tip.

Screening for CRC: USPSTF (United States Preventive Services Task Force) recommendations:

- Age 50-75: Screening Recommended
- Age 76-85: Recommends against routine screen, but consider on individual basis
- Age GT 85: Do not screen
- Choose one of the following

. Colonoscopy, every 10 years
. Flexible sigmoidoscopy, every 5 years, with high sensitivity FOBT every 3 years
. High sensitivity FOBT annually
..... Immunochemical FOBT (FIT)
..... Hemoccult Sensa

- Insufficient evidence of benefit or harm for CT Colonography

Screening for CRC: Consortium recommendations

- Average Risk: Start age 50
- Preferred Strategy: detect polyps & cancer

. Colonoscopy every 10 years
. Flexible sigmoidoscopy every 5 years
. Double-contrast barium enema every 5 years
. CT Colonography every 5 years

- Alternate: Tests that primarily detect cancer

. High-sensitivity FOBT (FIT vs Hemoccult Sensa) annually
. Fecal DNA, unspecified interval (recent 3 year interval per CMS)

Visualization methods preferred over indirect methods: Prevention vs Detection!

What to do? Best practices:

1. Visualize and remove all lesions by colonoscopy. Sigmoidoscopy and CT colonography are effective but somewhat inferior.
2. If above option is not chosen, then check stool for blood using Fecal Immunochemical Test (FIT)--note, only 2 samples are needed. If positive, follow up with colonoscopy. Fecal DNA is likely effective as well. Note that in the case of sigmoidoscopy, FOBT is likely necessary as well as the entire colon is not studied.

Special thanks to Dr. Henderson for this interesting and informative discussion.

Notes by Bill Elliott