DIJON, FranceIn patients with a history of colorectal adenomas,
use of a soluble fiber supplement (ispaghula husk) appears to have an
adverse effect on recurrence, said Jean Faivre, MD, of the European
Cancer Prevention Organi-sation (ECP) Study Group. The study also
showed that calcium supplementation produced a modest but not
significant reduction in the risk of adenoma recurrence.
665 Patients Randomized
Between 1991 and 1994, 665 patients with a history of colorectal
adenomas were enrolled in the study at 21 centers in 9 European
countries and Israel, said Professor Faivre, of Registre Bourguignon
des Tumeurs Digestives, Faculté de Médicine de Dijon.
They were randomly assigned to three groups: fiber supplement (3.5 g
of ispaghula husk daily), calcium supplement (2 g of elemental
calcium daily), or placebo. Ispaghula husk is a mucilaginous
substance used as an ingredient in some laxatives.
The calcium was administered twice daily in the form of two sachets
diluted in water; the fiber was given as one sachet of
orange-flavored effervescent granules diluted in water.
Colonoscopy was performed after 3 years. Of the 552 subjects who
completed the follow-up colonoscopic examination, 94 had stopped
treatment early, but the proportions who stopped prematurely did not
differ significantly between the treatment groups. A complete colon
exam was obtained in 539 patients.
During the 3 years of follow-up, at least one adenoma developed in 28
(15.9%) of the 176 participants receiving calcium, 58 (29.3%) of the
198 receiving fiber, and 36 (20.2%) of the 178 on placebo (Lancet
356:1300-1306, 2000). One person, receiving placebo, was diagnosed
with an invasive adenocarcinoma.
The risk of recurrence was significantly increased in patients
receiving the fiber treatment, Professor Faivre said, with an
odds ratio of 1.63. There was a nonsignificant risk reduction in the
calcium group (odds ratio, 0.75). Adjustment for age, sex, history of
adenoma, and number and location of adenomas at inclusion had little
effect on the results (adjusted odds ratio, 0.66 for calcium and 1.67
The adverse effect of the ispaghula fiber supplementation was
observed overall and in most subgroups of patients, which suggests
that it cannot be attributed to chance alone, he said.
The odds ratio for recurrence for those receiving fiber was
significantly higher in participants whose baseline dietary calcium
intake was above the median, compared with those with low calcium
intake (P = .028). This finding was unexpected, and we
cannot rule out that it was due to chance alone, he said.
The increased risk of recurrence with fiber supplementation was seen
for both small and larger adenomas, with no significant variations
according to the colon subsite. Professor Faivre noted, however, that
since very few patients developed large adenomas, we cannot
exclude the possibility of a beneficial effect of ispaghula husk on
later stages of carcinogenesis, such as adenoma growth and malignant
Finally, he said, there was no evidence that the adverse effect
of fiber could be explained by differential changes in dietary intake
by treatment groups during the trial.
Professor Faivre concluded that the findings do not accord with
the hypothesis of a protective effect of fiber on the risk of colon
cancer. He cited five previous studies showing no benefit for
fiber supplementation or a high-fiber diet.
He added, however, that the findings should not prevent
recommendations for high consumption of vegetables, fruits, and
cereals, because this approach has potentially beneficial effects on
other chronic diseases, especially coronary heart disease.