The Clinical Question: Managing Post-Colectomy Risk in FAP

Patients with familial adenomatous polyposis (FAP) face a lifelong battle against colorectal cancer. While the standard of care is a prophylactic colectomy to remove the primary risk, many patients undergo an ileorectal anastomosis to preserve bowel function. This leaves a rectal remnant that remains highly susceptible to developing hundreds of adenomatous polyps, necessitating frequent and invasive endoscopic surveillance.

While certain medications like celecoxib (a selective COX-2 inhibitor) are licensed to help reduce this polyp burden, they come with significant baggage—specifically concerns over long-term cardiovascular toxicity. This study sought to find a safer alternative. The researchers investigated whether a specific, highly purified form of omega-3 fatty acid—eicosapentaenoic acid (EPA)—could effectively reduce the number and size of rectal polyps in these high-risk patients.

The Approach: A Straightforward Comparison

The researchers conducted a randomised, double-blind, placebo-controlled trial. They recruited 58 patients with FAP who had already undergone a colectomy but still had a functioning rectum.

To ensure they were measuring the same polyps accurately, the team used a clever technique: they tattooed a small area of the rectal mucosa with sterile ink. This allowed them to count and measure the exact same cluster of polyps at the start of the study and again after six months.

The participants were divided into two groups:

• The Treatment Group: Received 2 grams daily of a novel, enteric-coated formulation of EPA in its “free fatty acid” form (EPA-FFA).
• The Control Group: Received an identical-looking placebo capsule containing medium-chain triglycerides.

Over the six-month period, the doctors used video endoscopy to track the “global polyp burden”—essentially a big-picture view of whether the rectum was getting better, staying the same, or getting worse. They also took small tissue samples to see if the EPA was actually being absorbed into the rectal lining.

Key Findings: Clear Reductions in Polyp Burden

The results were consistently in favour of the EPA treatment across all measured categories.

1. Fewer and Smaller Polyps

In the small tattooed areas where polyps were meticulously tracked, the difference was stark:

• Placebo Group: The number of polyps actually increased by nearly 10% over six months.
• EPA Group: The number of polyps decreased by over 12%.
• The Net Benefit: When comparing the two groups, those taking EPA saw a 22.4% reduction in the number of polyps compared to those on placebo.

The size of the polyps followed a similar trend. While the total diameter of polyps grew in the placebo group, it shrank in the EPA group, leading to a 29.8% net decrease in polyp size for those on the active treatment.

2. Global Improvement

When independent experts (who didn’t know which patient got which pill) reviewed the full endoscopy videos, they found that the overall state of the rectum worsened in the placebo group but showed modest improvement in the EPA group.

3. Proof of Absorption

The tissue biopsies confirmed that the treatment worked as intended. Patients taking the EPA capsules saw a 2.6-fold increase in the concentration of EPA within their rectal lining. Interestingly, levels of arachidonic acid (a pro-inflammatory fatty acid often linked to cancer growth) did not change significantly, suggesting the EPA might work through other pathways.

4. Safety and Side Effects

The treatment was remarkably well-tolerated. While some patients reported nausea (more common in the EPA group) or diarrhoea, the rates of most side effects were very similar between the two groups. Crucially, there were no reported bleeding issues or significant changes in blood tests.

Strengths & Limitations

Strengths

• Rigorous Design: The use of tattooing to ensure “apples-to-apples” comparisons of specific polyps is a major methodological strength that reduces measurement error.
• Clinical Relevance: By comparing their results to historical data on celecoxib, the authors provided a helpful “real-world” context for clinicians.
• Objective Evidence: Measuring the actual fatty acid content in the tissue proved that the supplement was reaching the target organ.

Limitations

• Small Sample Size: While the study was large enough to show a clear effect, 55 evaluable patients is still a relatively small cohort.
• Short Duration: Six months is enough to see polyps shrink, but it isn’t long enough to prove that EPA prevents actual rectal cancer or reduces the need for future surgery.
• Specific Formulation: The study used a specific “free fatty acid” form of EPA that is better absorbed than standard fish oil. We cannot be certain that standard over-the-counter fish oil capsules would produce the same results.

The Bottom Line

For clinicians managing FAP, this study provides high-quality evidence that 2 grams of EPA-FFA daily can effectively “mop up” existing rectal polyps and slow the growth of new ones. The magnitude of the effect appears remarkably similar to that of celecoxib, but with a much more attractive safety profile—particularly regarding cardiovascular health. While larger, longer-term trials are needed to see if this translates to fewer cancers, EPA-FFA represents a promising, low-risk adjunct to endoscopic surveillance for patients with a retained rectum.