Omega-3 After Bowel Cancer Surgery: High-Dose EPA Linked to Better 5-Year Survival in a New Trial
A simple-sounding supplement has produced a striking result in one of the hardest situations in cancer care. Patients who took high daily doses of an omega-3 fatty acid called EPA before and after surgery for bowel cancer that had spread to the liver were more likely to be alive five years later than patients who took a placebo. About 62% of the EPA group survived five years, compared with about 45% of the placebo group, according to results presented at a major cancer conference and reported on 30 October 2026.
That 17-percentage-point gap is large enough to matter, if it holds up. But the result comes with a puzzle and a warning: the findings have been presented at a conference but not yet fully peer-reviewed, and independent experts say confirmatory trials are needed before this becomes routine care. This article explains what the trial did, what it found, what it did not find, and what patients and families should — and should not — take from it.
A difficult operation, and a frequent return of the disease
Bowel cancer, also called colorectal or colon cancer, is one of the most common cancers worldwide. When it spreads, the liver is often the first place it reaches, because blood from the bowel flows directly to the liver. For some patients, surgeons can remove those liver tumours, offering a real chance of long-term survival.
The problem is that the cancer frequently comes back, either in the liver again or elsewhere in the body. That is why researchers keep looking for extra treatments, given around the time of surgery, that might tip the odds in the patient's favour. The new EPA trial is one such attempt, and its headline result is unusually encouraging for a low-cost, well-tolerated supplement.
What the trial did
The study recruited 418 patients in the United Kingdom scheduled for surgery to remove liver tumours that had developed from bowel cancer. Participants were randomly assigned to two groups: one took 4 grams of EPA (eicosapentaenoic acid) every day, the other a mineral oil placebo. Treatment ran before and after surgery, so the supplement was present during the operation and the recovery period.
Random assignment matters: the two groups should have been similar on average at the start, so survival differences are more likely to reflect the treatment. The trial was led by Professor Mark Hull of the University of Leeds, and the results were presented in Madrid at a meeting of the European Society for Medical Oncology (ESMO), one of the world's largest cancer conferences.
EPA is one of the main omega-3 fatty acids found in oily fish such as salmon, mackerel and sardines, and it is also sold as a supplement. The trial dose, 4 grams a day, is far higher than the amount most people get from food or a standard fish-oil capsule, and it was given as a purified preparation under trial conditions. That distinction matters, as we explain below.
What the trial found — and the puzzle inside it
The headline finding is the five-year overall survival difference: about 62% of patients taking EPA were alive after five years, versus about 45% of those taking placebo. Professor Hull described the benefit, if confirmed, as clinically meaningful for patients who have had surgery for bowel cancer spread to the liver, a group in whom the cancer frequently returns. He also noted EPA was well tolerated and safe, even alongside other cancer treatments.
But there is a twist that researchers themselves flagged. The time patients lived without their cancer getting worse — known as progression-free survival — was almost identical in the two groups: a median of 13.5 months with EPA versus 12.9 months with placebo. In other words, EPA did not obviously delay the return or growth of the cancer, yet more patients in the EPA group were alive at five years.
How can both things be true? Professor Hull offered a possible explanation: the benefit may reflect how a patient's body responds to cancer overall, rather than a direct attack on the tumour. People with advanced cancer often suffer weight loss, reduced appetite and fatigue — a wasting syndrome called cachexia — which wears the body down and can limit further treatment. If EPA helps patients stay stronger and better nourished, they may cope better with later treatments and live longer even if the cancer progresses on a similar timetable. Hull also noted a parallel with immunotherapy trials, where longer overall survival without matching progression-free survival gains has been seen before, and suggested research should test whether EPA works partly through the immune response.
That explanation is a hypothesis, not a proven mechanism. It fits the pattern of the numbers, but the trial as presented does not prove it — that is a question for the full publication and follow-up studies.
Why researchers looked at omega-3s in the first place
The idea did not come from nowhere. Omega-3 fatty acids have been studied for years for their effects on inflammation, which is closely involved in how cancers grow and spread. High-dose purified EPA has also been investigated in heart disease, so researchers already had safety data and experience with the 4-gram dose range.
There is a practical appeal too. Compared with most cancer drugs, EPA is inexpensive, widely available, and — in this trial — well tolerated. If a cheap, safe addition to surgery genuinely improved survival, it would be unusually good news. That promise is precisely why the result deserves both attention and caution.
For readers thinking about diet, keep the distinction between food and trial treatment clear. Eating oily fish as part of a balanced diet is a sensible habit, which is why our complete guide to healthy eating includes oily fish among its recommended foods. But a portion of salmon is not 4 grams of purified EPA taken daily under medical supervision, and this trial does not show ordinary fish-oil capsules or a fish-rich diet would give the same benefit.
What independent experts said
Independent reaction to the results has been positive but careful. Dr Chiara Cremolini, an associate professor of medical oncology at the University of Pisa in Italy who was not involved in the study, called the findings "definitely intriguing, from both a biological and a clinical point of view." She added that confirmatory results are likely needed before the treatment could be incorporated into daily clinical practice.
Cremolini also pointed to a real challenge for future trials: patients needing liver-tumour surgery can have very different treatment histories and tumour biology, and those differences affect outcomes. Future studies will need to account for that variety, ideally by testing EPA in more precisely defined patient groups, so doctors can learn who benefits most — if anyone does.
What this does not mean
It is easy to over-read a headline like this, so here is what the trial does not show.
First, it does not show that omega-3 supplements prevent bowel cancer. This was a treatment study in people who already had advanced cancer and were undergoing liver surgery, not a prevention study in healthy people. Our earlier look at ultra-processed foods and colon cancer risk covers some dietary patterns linked to that risk question.
Second, it does not show that people should start taking 4 grams of EPA on their own. High doses can interact with other medicines — omega-3s can affect blood clotting, which matters around surgery — and the trial's EPA was a defined preparation given with medical oversight. Anyone with cancer, or facing surgery, should discuss supplements with their oncology team rather than self-prescribing.
Third, it does not yet change standard care. Until the results are published in full and confirmed, doctors are unlikely to add EPA to routine treatment, and patients should not expect it as standard. That may feel frustrating when the numbers look so good, but it is how medicine avoids building practice on a single result that might not survive re-testing.
Where this fits in the wider cancer picture
The EPA result arrives as cancer treatment advances on several fronts at once, often by combining approaches. Surgery remains central for liver metastases, chemotherapy and targeted drugs play supporting roles, and newer immune-based treatments are changing expectations in several cancers. In that landscape, a well-tolerated addition that improves survival after surgery would be valuable even if its effect turns out modest — and the gap reported here, if real, is far from modest.
It is also a reminder that progress does not always come from the most expensive new technology. Some of the most useful advances have been repurposed or low-cost interventions, tested rigorously in randomised trials — take a well-understood substance, test it properly, and let the survival numbers speak. The same spirit drives very different innovations, from the mRNA vaccine that cut melanoma recurrence in a recent phase 3 trial to new surgical techniques. The common thread is randomised evidence, not novelty for its own sake.
What to watch next
Three things will determine whether EPA becomes part of standard care. The first is the peer-reviewed publication, which should reveal details the conference talk could not: prior treatment, side effects by group, and whether the benefit held across subgroups such as patients who had prior chemotherapy. The second is confirmation: an independent, ideally larger and multinational trial showing a similar survival advantage. The third is mechanism: work testing whether EPA really acts through the body's response to cancer — weight, appetite, fatigue, immune function — rather than directly slowing tumour growth.
If those pieces fall into place, EPA could become a low-cost addition to care for patients who badly need better odds. If they do not, the trial will still have been worth doing: unconfirmed results are how medicine avoids wasting patients' time and hope on treatments that do not work.
The bottom line
A randomised trial of 418 UK patients found high-dose EPA taken around liver surgery for bowel cancer spread was associated with five-year survival of about 62%, versus about 45% on placebo — but with almost no difference in how long patients lived before their cancer progressed. That combination is intriguing, and the explanation that EPA may help the body withstand cancer and its treatment is plausible but unproven. Independent experts want confirmatory evidence before this enters routine practice, and the findings await full peer review. For now, the honest summary is: a genuinely promising result, in a genuinely hard disease, that still needs to be confirmed.
*This article is for general information only and is not medical advice. If you have bowel cancer or are facing liver surgery, talk to your oncology team about any supplement or treatment change. Do not start or stop any supplement or medicine on the basis of a news report about a conference presentation.*