Structured Exercise after Adjuvant Chemotherapy for Colon Cancer 2025 Courneya et al

Abstract

Background
Preclinical and observational studies suggest that exercise may improve cancer outcomes. However, definitive level 1 evidence is lacking.

Methods
In this phase 3, randomized trial conducted at 55 centers, we assigned patients with resected colon cancer who had completed adjuvant chemotherapy to participate in a structured exercise program (exercise group) or to receive health-education materials alone (health-education group) over a 3-year period. The primary end point was disease-free survival.

Results
From 2009 through 2024, a total of 889 patients underwent randomization to the exercise group (445 patients) or the health-education group (444 patients). At a median follow-up of 7.9 years, disease-free survival was significantly longer in the exercise group than in the health-education group (hazard ratio for disease recurrence, new primary cancer, or death, 0.72; 95% confidence interval [CI], 0.55 to 0.94; P=0.02). The 5-year disease-free survival was 80.3% in the exercise group and 73.9% in the health-education group (difference, 6.4 percentage points; 95% CI, 0.6 to 12.2). Results support longer overall survival in the exercise group than in the health-education group (hazard ratio for death, 0.63; 95% CI, 0.43 to 0.94). The 8-year overall survival was 90.3% in the exercise group and 83.2% in the health-education group (difference, 7.1 percentage points; 95% CI, 1.8 to 12.3). Musculoskeletal adverse events occurred more often in the exercise group than in the health-education group (in 18.5% vs. 11.5% of patients).

Conclusions
A 3-year structured exercise program initiated soon after adjuvant chemotherapy for colon cancer resulted in significantly longer disease-free survival and findings consistent with longer overall survival. (Funded by the Canadian Cancer Society and others; CHALLENGE ClinicalTrials.gov number, NCT00819208.)

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A 7% difference between groups is reported as....

Major study shows exercise improves cancer survival

"An exercise programme for colon cancer patients can cut the risk of dying by a third, a major international trial shows.

The researchers said it was "not a large amount" of exercise and any type of workout from swimming to salsa classes counted.

The results could change the way colon cancer is treated around the world.

Scientists are already investigating whether similar exercise regimes could improve survival for people with other diseases, such as breast cancer.

"It's a bit of a mind-shift, thinking of treatment as something you do, not just something you take," says researcher Prof Vicky Coyle from Queen's University Belfast."

https://www.bbc.co.uk/news/articles/c8xgyw7k7veo

 

Ah, the SMC is in on the hype, https://www.sciencemediacentre.org/...d-reduced-risk-of-recurrence-of-colon-cancer/

 

Adherence was really low.

 

Have they accounted for the lower recruitment, and especially the lower amount of events detected?

What about multiple testing?

And they forgot to mention in the abstract that they only recruited the less severe patients.

 

That seems accurate. 7% reduction in absolute risk, but that's influenced by how rare or common the event of dying in that timeframe is in general.

But if ~17% of people died in the control group and ~10% died with exercise, that's more than a third less that died over the 8 years. And the hazard ratio of .63 indicates a 37% lower mortality rate in the exercise group.

 

Only read the abstract but sounds like an impressie difference.

 

So the treatment group got not only exercise training but lots of personal contact with HCPs (and "behavioural support"); did the control group get anything to match that?

 

No, I don’t think so. But they do mention that other studies found no survival benefit from contact alone.

 

The Guardian headline for this is criminal:
Exercise ‘better than drugs’ to stop cancer returning after treatment, trial finds

https://www.theguardian.com/society...er-cancer-treatment-international-trial-finds

I’m of the opinion these sorts of headlines can cause excess deaths by convincing people they don’t need medical care and can just solve the cancer themselves with healthy living

 

Very much so, a dreadful headline.

I find it quite hard to believe that there isn't a flaw here somewhere relating to greater supervision in the exercise group. Multicentre studies are very open to abuse because decisions are delegated to all sorts of people who may not understand the need for rigour. Whenever there is some outcome which isn't quite clear it will get biased if the trial is open like this.

What the abstract does not say specifically is the difference in recurrence of the original tumour. That is the only thing I would take note of. If anything the bias would be likely to be the other way if there was more supervision.

 

It does look good, but I wonder if they controlled for factors such as existing health conditions and disability that might mean some of the non-survivors were potentially more unwell to start with?

Or that people who're less likely to engage (or be able to engage) might have other major risks that add to mortality regardless of whether or not they have cancer? The effects of poverty and the complex web of issues associated with it are far from trivial.

 

Presumably, if recruitment was slow, it is likely/possible that the cohort recruited were a rather special group of people who were very motivated to have an exercise training programme - 'Ooh, yes please, I'll do that trial'. In which case the result might imply that telling people that they didn't get the personal training option worsens their chances of survival more than telling people they cannot have more chemo!!

Maybe what they should have done is randomise all patients who fit inclusion criteria and only offer exercise to the ones that drew that option. If only 5% said yes please that would mean you would get a more realistic picture of what offering exercise does.

Trouble is that trials like that are usually unethical. You cannot enrol people in trials and not tell them they were enrolled but drew blank (I think).

If recruitment was very slow you can probably divide the apparent benefit by five or ten for the real world.

 

There were 12 cases of recurrence in the «local colon» in both groups.

 

It was. They spent 15 years and didn’t meat their quota, and had far fewer events than what they powered the study for.

 

The biggest difference is for new breast cancer. Breast cancer is associated with BMI I think but the difference is striking

For recurrence I think the overall figure is relevant - which shows just slight overlap in confidence limits but is not trivial

 

Steve Jobs is, uh, yeah, probably not recommending this framing. As you say, this headline is frankly criminal. It will lead to some literally choosing to try exercise over treatment. If quacks like RFK Jr see this you can bet they will hype it to the max.

I may be too cynical, but I don't believe it. Studies like this are always too poor to be reliable, and always end up being too good to be true. I'll wait for more, assuming that this amazing stupendous groundbreaking number will drop by a lot with more rigorous investigation.

Because, really, if it was that simple and effective, how in the hell would this have not been obvious for decades? There is literally nothing in this study that couldn't have been done a century ago, or at any point since.