How Tumors Exploit Gut Flora to Fuel Growth, and the Surprising Finding that Chemotherapy Boosts Resistant Cancer

October 24 2012

By Dr. Mercola

Could your gut flora play a role in cancer growth? According to recent research, the answer is a tentative yes.

Findings published in the journal Nature¹ report the discovery of microbial-dependent mechanisms through which some cancers mount an inflammatory response that fuels their development and growth. These findings provide new insight into how cancer cells can hijack your body's inflammatory reaction by exploiting microbial-dependent immune cells.

As reported by Medical News Today:²

"The association between chronic inflammation and tumor development has long been known from the early work of German pathologist Rudolph Virchow. Harvard University pathologist Harold Dvorak later compared tumors with 'wounds that never heal,' noting the similarities between normal inflammation processes that characterize wound- healing and tumorigenesis or tumor-formation.

Indeed, 15 to 20 percent of all cancers are preceded by chronic inflammation - a persistent immune response that can target both diseased and healthy tissues... Still, most cancers are not preceded by chronic inflammation.

On the other hand, they exploit ubiquitous, infiltrating immune cells to unduly provoke and hijack the host inflammatory reaction. Until now, the mechanism of so-called 'tumor-elicited inflammation,' which is detected in most solid malignancies, was poorly explained.

'The tumor-associated inflammatory reaction... may hold the keys for future preventive and therapeutic measures,' said first author Sergei Grivennikov, Ph.D

Noting that studies of long-term users of non-steroidal anti-inflammatory drugs, such as aspirin, have revealed that general inhibition of inflammation reduces the risk of cancer death by up to 45 percent, depending on the type of cancer. 'So inhibition of inflammation during cancer development may be beneficial.'"

How Even Beneficial Gut Bacteria Might Spur Colon Cancer Growth

The research centered around colon cancer. What may be surprising is that the intestinal bacteria involved in this inflammatory mechanism are not necessarily the pathogenic variety, but rather ordinarily benign microflora.

The reason for this is because as the tumor develops, it disrupts the normal, healthy functioning of tissues, and because tumors lack a particular protein that normally coats and protects tissue cells, normal microflora present in your colon can enter the tumor. Since the bacteria does not "belong" there, your immune cells recognize them as invaders, and launch an inflammatory response.

The presence of microbial products are also picked up by macrophages (white blood cells) and immune cells within the tumor, which in turn produce cytokines that further spurs the inflammatory process. One of the primary cytokines involved is Interleukin-23, which regulates inflammation and triggers the production of other inflammatory cytokines that promote tumor development and progression.

The researchers were able to reduce tumor-elicited inflammation and tumor growth by using a combination of broad-spectrum antibiotics. Antibiotics, as you probably know, indiscriminately kill off all types of intestinal bacteria, and by reducing the normal microflora, tumor growth and related inflammation diminished.

According to Grivennikov:³

"This is a very nice demonstration of how tumor-elicited inflammation in cancers that arise in the absence of underlying chronic inflammatory disease can be induced... The next step is to look for the upregulation of Interleukin-23 and related cytokines in colon cancer patients, inhibit these cytokines and determine whether these impact cancer progression and response to therapy."

While tumor growth and tumor-elicited inflammation was reduced, I would caution you to not get confused and think that heavy-handed antibiotic use might spare you from colon cancer. I believe this would be a serious mistake... The key, I think, is to place a greater focus on optimizing gut health, to prevent and naturally counteract the development of inflammation in the first place.

The idea that you might be able to halt colon cancer proliferation by eradicating your microflora, or designing a drug to prevent cytokine production is bound to cause some serious side effects. Cytokine production occurs in response to inflammation, so just inhibiting them is not actually going to resolve the underlying inflammation...

And you clearly cannot be healthy without normal gut flora, so eradicating it to prevent tumor growth would likely be disastrous in the long term. What you want to do is encourage the proliferation of beneficial bacteria, which by competitive inhibition, will limit or decimate the populations of pathogenic bacteria, yeasts and fungi. This is largely done by limiting fuel for the pathogens, which would include sugars and non-fibrous carbs, and providing loads of beneficial bacterial supplements like fermented vegetables.

As Grivennikov says, inhibiting inflammation during cancer development is likely a vital component of prevention. The question is how to properly inhibit inflammation, and in my view, inhibiting inflammation through healthy lifestyle choices makes a whole lot of sense, as opposed to taking drugs.

Your Gut Affects Your Metabolism and Genetic Expression

As time goes on, we're gaining more and more information about the important roles gut flora plays in maintaining overall health. The good news is that this is an area you can exercise a lot of control over. Your diet can quickly alter the composition of your gut flora. Processed foods high in sugar and chemical additives and low in nutrients is a surefire way to decimate the beneficial bacteria in your gut, allowing the harmful pathogenic kind to thrive.

Research has also shown that your microflora has a significant impact on gene expression, such as the genes responsible for vitamin biosynthesis and metabolism. Probiotics have been found to influence the activity of hundreds of your genes, helping them to express in a positive, disease-fighting manner – some of which affect your body in a manner resembling the effects of certain medicines. Probiotics (healthy bacteria) has over 30 beneficial pharmacological actions that we know of, including those listed below.⁴

Note that probiotics downregulate interleukin-6, one of several cytokines involved in inflammatory processes, so probiotics may turn out to be an important player in helping to inhibit cytokine production – as suggested by Grivennikov above – and control inflammation that might otherwise lead to colon cancer:

Anti-bacterial Anti-allergenic Anti-viral Immunomodulatory

Anti-infective Antioxidant Antiproliferative Apoptopic (cellular self-destruction)

Antidepressive Antifungal Cardioprotective Gastroprotective

Radio- and chemo protective Upregulates glutathione and certain glycoproteins that help regulate immune responses, including interleukin-4, interleukin-10, and interleukin-12 Downregulates interleukin-6 (a cytokine involved in chronic inflammation and age-related diseases) Inhibits tumor necrosis factor (TNF) alpha inhibitor, NF-kappaB, epidermal growth factor receptor, and more

The Ideal Way to Optimize Your Gut Health

Historically, people didn't have the same problems with their gut health as we do today for the simple fact that they got large quantities of beneficial bacteria from their diet in the form of fermented or cultured foods, which were invented long before the advent of refrigeration and other forms of food preservation.

You can ferment virtually any food, and every traditional culture has traditionally fermented their foods to prevent spoilage. There are also many fermented beverages and yoghurts. Quite a large percent of all the foods that people consumed on a daily basis were fermented, and each 2-3 ounce serving of an ideally prepared food can provide trillions of beneficial bacteria – far more than you can get from any probiotic supplement.

In fact, it's unusual to find a probiotic supplement containing more than 10 billion colony-forming units, but when my team tested fermented vegetables produced by probiotic starter cultures, they had 10 trillion colony-forming units of bacteria. Literally, one serving of vegetables was equal to an entire bottle of a high potency probiotic! Fermented foods also give you a wider variety of beneficial bacteria, so all in all, it's your most cost effective alternative.

Fermenting your own foods is a fairly straight-forward and simple process, and can provide even greater savings. To learn more, please listen to my interview with Caroline Barringer, a Nutritional Therapy Practitioner (NTP) who has been involved with nutrition for about 20 years.

More: http://articles.mercola.com/sites/articles/archive/2012/10/24/tumors-exploit-gut-flora.aspx?e_cid=20121024_DNL_art_1

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