Fiber supplement may help prevent certain types of hereditary cancer
Individuals with Lynch syndrome who took resistant starch supplements for at least 2 years developed significantly fewer non-colorectal cancers, results of a 10-year follow-up study in Cancer Prevention Research showed.
Researchers found the most pronounced protective effect of resistant starch — also known as fermentable fiber — for upper gastrointestinal malignancies, including pancreatic, esophageal, biliary tract and gastric cancers.
The results may be the first to indicate that dietary supplementation can help prevent certain forms of cancer among people with Lynch syndrome, investigators noted.
Background
Individuals with Lynch syndrome are at increased risk for several types of cancer — particularly colorectal cancer.
Researchers designed the international CAPP2 study to determine whether the effects of aspirin or nutritional supplementation with resistant starch influenced the development of subsequent cancers among people with Lynch syndrome.
“We have a long-term interest in cancer prevention and have argued that carrying out chemoprevention studies in people with hereditary cancer — such as Lynch syndrome — is a very cost-effective way of finding out not only what works in these patient groups but also in providing evidence that might be relevant for cancer prevention in the general population,” John Mathers, BSc, Dip Nutr, PhD, professor of human nutrition at Newcastle University in the United Kingdom, told Healio.
Methodology
The multinational CAPP2 trial used a 2 × 2 factorial design that allowed for simultaneous evaluation of aspirin use and dietary supplementation with resistant starch among people with Lynch syndrome. Study participants willing to take both interventions had equal probability of being assigned to one of four study arms: aspirin plus resistant starch, placebo plus resistant starch, aspirin plus placebo, or dual placebos.
The current analysis included 918 study participants (mean age, 45 years), of whom 463 received 30 g resistant starch daily and 455 received placebo. Treatment continued for up to 4 years.
Mathers and colleagues presented data from a planned 10-year follow-up analysis of the study results, supplemented by national cancer registry data up to 20 years for 369 participants from England, Wales and Finland.
The number, size and histologic stage of colorectal carcinomas served as the study’s primary endpoint. Secondary endpoints included number, size and histologic stage of Lynch syndrome-related non-colorectal carcinomas.
Key findings
Twenty-year follow-up data showed no difference in colorectal cancer incidence among study participants who received resistant starch and those who received placebo.
However, using an intent-to-treat analysis, investigators observed significantly fewer Lynch syndrome-related non-colorectal cancers among individuals who received resistant starch supplementation compared with placebo (27 vs. 48; HR = 0.54; 95% CI, 0.33–0.86).
An incidence rate ratio of 0.52 (95% CI, 0.32–0.84) confirmed the significant protective effect of resistant starch against Lynch-syndrome-related non-colorectal cancers.
Researchers found the most prominent protective effects against upper GI tract cancers. Five study participants who received resistant starch supplementation developed subsequent upper GI cancers compared with 21 of those who received placebo.
Clinical implications
Results from the CAPP2 trial are the first to show that dietary intervention can reduce cancer risk among people with Lynch syndrome, Mathers said.
“This is clinically important because, at present, there are no easy-to-use ways of screening for these upper GI cancers, so they are usually diagnosed late,” he told Healio. “This is in contrast with cancers of the large bowel, [such as colorectal cancer, which] can be managed effectively through regular screening programs.”
People with Lynch syndrome typically do not undergo regular screening for non-colorectal cancers and, as a result, they are often detected later and outnumber colorectal cancer-related deaths among those with the condition, Mathers said.
“Indeed, cancers of the upper GI tract are much more likely to be lethal than are [colorectal cancers] in people with Lynch syndrome,” he added.
“We were disappointed when we discovered that those randomized to resistant starch in the CAPP2 study had very similar [colorectal cancer] incidence to those randomized to placebo,” Mathers said. “However, we were very surprised — and encouraged — by the approximately 50% reduction in non-colorectal cancers among those randomized to resistant starch.”
For more information:
John Mathers, BSc, Dip Nutr, PhD, can be reached at Population Health Sciences Institute, Room 2.060, William Leech Building, Newcastle University, Newcastle on Tyne, NE2 4HH, United Kingdom; email: john.mathers@ncl.ac.uk.
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