Bowel cancer (also called colorectal or colon cancer) is the second biggest killer of Australians from cancer each year. This is one form of cancer where diet and lifestyle choices play a big part in changing a person’s risk of developing it. But once someone is diagnosed with cancer, the outlook changes. Now emerging research is finding that the use of probiotic supplements taken in conjunction with active treatments of surgery, chemotherapy or radiotherapy can have a beneficial effect on the outlook of people with bowel cancer. And that’s the topic I’ll cover in this podcast episode.
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Bowel cancer (also called colorectal or colon cancer) is the second biggest killer of Australians from cancer each year. This is one form of cancer where diet and lifestyle choices play a big part in changing a person’s risk of developing it. But once someone is diagnosed with cancer, the outlook changes. Now emerging research is finding that the use of probiotic supplements taken in conjunction with active treatments of surgery, chemotherapy or radiotherapy can have a beneficial effect on the outlook of people with bowel cancer. And that’s the topic I’ll cover in this podcast episode.
Links referred to in the podcast
Episode transcript
To access the full episode transcript, go to the following link and select the individual podcast episode and then click on the ‘Transcript’ tab https://thinkingnutrition.buzzsprout.com
Connect with me
Instagram: doctimcrowe
Facebook: Thinking Nutrition
Twitter: CroweTim
Bowel cancer (also called colorectal or colon cancer) is the second biggest killer of Australians from cancer each year. This is one form of cancer where diet and lifestyle choices play a big part in changing a person’s risk of developing it. But once someone is diagnosed with cancer, the outlook changes. Now emerging research is finding that the use of probiotic supplements taken in conjunction with active treatments of surgery, chemotherapy or radiotherapy can have a beneficial effect on the outlook of people with bowel cancer. And that’s the topic I’ll cover in today’s podcast episode.
Bowel cancer is the second biggest killer of Australians from cancer each year. Almost 16,000 people are diagnosed with bowel cancer every year in Australia though the good news is that rate has been falling when you account for an ageing population as age is the biggest overall risk factor for most cancers. Bowel cancer can occur in any part of the colon or rectum, either growing from the inner lining of the bowel or from small growths on the bowel wall. Undetected, bowel cancer can spread into the wall of the bowel, the lymph nodes and then on to other organs.
Lifestyle factors account for half of all bowel cancer cases. Another quarter of cases are explained by genetics and family history. Those lifestyle factors can be summed up as not eating enough foods high in fibre such as fruits, vegetables and wholegrains, eating too much red and processed meat, carrying too much weight, not being active enough, smoking and drinking too much alcohol. If you want to learn more about this topic, then check out one of my previous podcasts, episode 38, where I covered five different ways to cut your risk of bowel cancer.
But what about when someone has bowel cancer and is undergoing active treatment? At this time, the focus is more about tolerating treatment and staying as healthy as possible. One such common treatment for bowel cancer is radiotherapy.
Radiotherapy is an effective treatment for certain types of cancers, but like any cancer treatment, it is not without its side effects.
Depending on what part of the body is being targeted by the radiotherapy, and the duration of the treatment, side effects can vary. Common side effects include fatigue, skin burning and inflammation, loss of appetite, swallowing problems, nausea, and diarrhoea.
If radiotherapy is being targeted to the stomach or lower abdomen, then diarrhoea is a very likely consequence. While the radiotherapy is effective in destroying cancer cells in this area, healthy cells lining the bowel can succumb to ‘friendly fire’. Up to 90 percent of people receiving lower abdomen radiotherapy can experience some form of ongoing disruption to their bowel habits which can persist for months to even years after treatment.
Researchers have wondered for some time if the advice to people receiving radiotherapy to follow a lower fibre diet to help mitigate some of the problems of diarrhoea and gastrointestinal problems from treatment could have some adverse consequences. One of these potential problems is causing a change in the intestinal bacterial microflora profile of the gut. Enter the idea of trialling probiotic supplements in people receiving radiotherapy to help maintain and support the normal gut bacteria population.
Probiotics are foods or dietary supplements that contain beneficial bacteria which are normally found in the body. Fermented milk products such as yoghurt, sour cream, buttermilk and commercial off-the-shelf probiotic supplements are all available. Although probiotics are not considered essential to health, the microorganisms they contain may assist with digestion or help protect against harmful bacteria by improving the workings of the immune system.
There have already been several small-scale clinical trials exploring the benefit that probiotics can have on radiation-induced bowel disease caused by radiotherapy. When the clinical trials are considered on their own, it is hard to see if there is a clear benefit or not. Scientists though have collated all the research together in the form of a systematic review and meta-analysis to see if there is a key message from the research field which I’ll link to in the show notes. https://www.sciencedirect.com/science/article/abs/pii/S0261561413000502
All up, 10 randomised-controlled clinical trials were identified which used a range of probiotic supplements. Six of the clinical trials were considered of good enough quality to form part of the meta-analysis. The results appeared favourable with a significant reduction in the incidence of diarrhoea by over 50 percent when comparing people given probiotics against a control group. Although not achieving the level of statistical significance, there was a trend for lower use of anti-diarrhoeal medications and fewer reports of watery stools.
So, the results looked good. But this review was published way back in 2013 and since then, a lot more work in the broader space of using probiotic supplements in people with bowel cancer has been published. And this was the topic of a just-published systematic review and meta-analysis. All up, 23 randomised-controlled trials were included that compared the effect of probiotic supplementation versus a placebo in people with colorectal cancer. And I’ll link to this study in the show notes. https://academic.oup.com/nutritionreviews/article-abstract/80/1/22/6283538
Now there was a lot of data in the review, so here are the overall findings put forward by the research team.
Probiotic supplementation in people with colorectal cancer improved their quality of life, enhanced the diversity of the gut microbiota, reduced the risk of infections following surgery and inhibited pro-inflammatory cytokine production. That is a pretty impressive list of topline findings.
And to add to that, there was also evidence that probiotics reduced the side effects of chemotherapy, improved the outcomes of surgery, shortened the amount of time spent in hospital stays, and overall, decreased the risk of death.
The four clinical outcomes that showed the highest level of evidence grade were: modulation of the immune system and inflammatory biomarkers, length of hospital stay, quality of life, and colorectal tumour growth.
And the studies overall were rated quite highly for having a low risk of inherent bias in them which adds strength to the results.
So, the big question: what were the probiotics used? As you would expect, studies used a wide variety of types and doses of probiotics, but it was Bifidobacteria and Lactobacillus that were the common probiotics used across most studies. But half of the studies used a mixture of different strains of probiotics as an intervention so there wasn’t one particular species or strain of bacteria that stood out.
And it didn’t seem to matter much what form the probiotic was given be it powdered in a capsule or infused into a drink. Dosage and how long it is taken for were more important. This is especially important if you look at trials that used probiotic supplements both before and after surgery or chemotherapy which showed a better indication of a benefit.
With this level of evidence now accumulated, it increasingly seems that the use of a cheap and simple nutritional intervention with probiotics shows promise in having a role in managing colorectal cancer treatment-related side effects and overall health and cancer-related outcomes. With further studies likely to add to the evidence base in the future, the use of probiotics could become a standard part of treatment for people diagnosed with colorectal cancer.
Finally, a disclaimer: the information presented in this podcast should not be taken as medical advice that you should take probiotics or advise others to take them with bowel cancer without first viewing the research evidence in greater depth and speaking about it to your treating medical team.
So that’s it for today’s show. You can find the show notes either in the app you’re listening to this podcast on if it supports it, or else head over to my webpage www.thinkingnutrition.com.au and click on the podcast section to find this episode to read the show notes.
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I’m Tim Crowe and you’ve been listening to Thinking Nutrition.