Saturday, July 05, 2008

Family and fiber: Colorectal cancer risk

I'm always recommending a screening colonoscopy to my patients 'of age,' after all, I had one, therefore, so can they. Here's the top two excuses (after 'I'm a chicken' and 'I'm embarrassed') that people give me for not undergoing this important screening test, and here's what I have to say to them:

1) No one in my family has colon cancer. While having a first degree relative (parent or sibling) with a history of colorectal cancer (CRC) increases risk 2-fold, 80% of persons who get CRC have no such family history.

2) I eat a high fiber diet. Boston doctors undertook a prospective study of nearly 89,000 women ages 34-59 in 1980.(1) They found no association between dietary fiber intake and the risk of CRC during 16 years of follow-up.

One might raise the question, as did Dr. Neil Raven(2), as to what really constitutes a high fiber diet. He responded to the above study in a letter to the editor wondering if the flaw in the study's design might not be that Boston women who say they eat high fiber aren't really as fiber-filled as they think. He cited information from Dr. Denis Burkitt, a physician who spent time in West Africa studying lifestyle and disease. Per Dr. Raven:

Burkitt began his lecture with a slide showing a stool of a typical Western, "civilized" person, a sausage-shaped thing, familiar to most of us, in a toilet bowl. His next slide was of a stool of a typical rural West African, which looked like a flat cow pie. Burkitt postulated that the West African's stool moved more quickly through the colon, giving carcinogens contained on its surface less time to be in contact with the mucosa — thus less time to induce carcinogenesis.

During the question-and-answer period, many questions from the audience concerned how one determined whether or not a diet was high in fiber in the sense Burkitt meant. Burkitt shook his head at all the salads, cereals, and breads offered as sources of fiber. He showed a slide of the staple cereal eaten by West Africans, which looked, in its wooden bowl, not too different from the stool that came out the other end. The only thing the study by Fuchs et al. proves is what anyone who heard Burkitt's lecture already knew: the American public has been sold a sugar-coated misconception.

(1)Fuchs, CS et al. Dietary Fiber and the Risk of Colorectal Cancer and Adenoma in Women. NEJM Volume 340:169-176 January 21, 1999 Number 3.

(2)Raven, ND. Dietary Fiber and Colorectal Cancer. NEJM Volume 340:1924-1926 June 17, 1999 Number 24.


JeanMac said...

But I don't wanna - pout. I guess I best talk to my trusty MD.
Do they give out any prizes after or only before?!

Anonymous said...

All well and good. But for the low-risk patient who is willing to do yearly hemoccults, I don't push too hard. Just got through getting a low-risk, asymptomatic patient (who just wanted a colonoscopy because she'd read she needed one, so I sent her) through a laparotomy with a colostomy for 3 months followed by another surgery to take the thing down. She was in her 50's and otherwise healthy, so no way to see this coming. This happened in the hands of a very good, experienced gastroenterologist who's been doing these procedures for 20 years. It doesn't take but one of these to make you think twice.

Mauigirl said...

Scary scenario, there, Anonymous. I keep trying to convince my husband to get a colonoscopy and he keeps citing the rather high 1 in 1000 chance of perforation as a reason not to do it. I pooh-poohed it but I guess it does happen. I'll try to convince him on the occult blood test instead.

In the meantime I'll probably go have my colonoscopy! Had one 7 years ago and am 54 now and probably should have one again.

dorsey said...

about the west african diet; yes, lots of millet, looks more like soup than our idea of cereal, add some cooked-at-least-an hour vegetables and peanut sauce, (plus lots of salt and MSG) but I'd bet what causes the cow-pie shape are parasites. I'm not talking Jamie Lee's yogurt microbes, I mean critters you can see having a swim meet in that mess.

One other difference, the people there tend to be happy, no cultural pressure to go after material things, so maybe the way to avoid colon problems is to de-stress and take on some amoebas. I think this may be a "choose your poison" dilemma.