The Antibiotic Cancer Connection

Written by Dr. Colin Champ
Posted November 19, 2014 at 7:00PM

"If all the medicine in the world were thrown into the sea, it would be bad for the fish and good for humanity"

-Oliver Wendell Holmes

Last week we discussed the important function of our normal bowel bacteria. This week, we take a look at the connection between our bowel bacteria, antibiotics, and cancer.

Normal Bacteria Help Us to Fight Cancer

A recent study has even revealed that normal bowel bacteria may be necessary for chemotherapy to provide its full anticancer effect.1 Cyclophosphamide, a commonly used chemotherapy for leukemia and lymphoma, directly damages cancer cells, but also stimulates a response within the body to fight the cancer cells with our own natural immune cells.

When scientists took mice and gave them antibiotics, the germ-free mice experienced a significantly reduced response of their own immune cells in the form of T cells. Worse-off, their tumors appeared to be resistant to cyclophosphamide. The authors concluded that the bacteria within the bowel (gut microbiota) help to mount the response of the immune system to fight cancer.

If normal bacteria have been shown to help in the fight against cancer, it is not unreasonable to think that eliminating these troops would leave the human body more vulnerable to cancer.

Normal bacteria help to stimulate our immune system, which helps to fight cancer.

A similar study reveals further detriment in our normal immune cells with antibiotic usage. While the scientists above showed the lessening effect on chemotherapy efficacy with antibiotic usage in regards to our T cells, other studies show the influence on other immune cells that results from antibiotic usage.2

When given antibiotics to create “germ-free” mice, the response of tumors to immunotherapy, a newer type of cancer treatment that stimulates the body’s immune system, is significantly less. Fewer free radicals are formed within the tumors of these mice (which is how chemotherapy and radiation therapy work to damage and kill cancer cells) and chemotherapy is also left as less effective.

The authors said it best with “optimal responses to cancer therapy require an intact commensal microbiota that mediates its effects by modulating myeloid-derived cell functions in the tumor microenvironment.”

In other words, cancer treatment requires an intact and functioning bacterial system within the bowel. Where does that leave us if we sterilize the bowel with antibiotics?

Over-prescribed, Over-utilized, Under-warranted

Cutting physicians some slack, I have seen many patients come in gunning for antibiotics, refuse to take no for an answer, and will not leave without a prescription. If you continually ask your physician to prescribe you antibiotics for your yearly cold or sinus infection, stop.

Viral infections are much more common, in which case antibiotics are only doing us more harm by depleting our naturally occurring bacteria in the sinuses and bowels, leaving a state of inflammation behind, and leaving us more susceptible to infection. Others have hypothesized that these same effects of antibiotics leave us at risk for cancer.3

Another massive issue with over usage of antibiotics is the development of antibiotic-resistant bacteria, and this may even alter gene function in the gastrointestinal tract.4

The Solution

The easy thought is to avoid antibiotics, but that is obviously not always possible. In fact, as I type this, I am just over a long course of antibiotics for Lyme disease (after having a tick lodged in my leg for a week with a bull’s-eye rash).

The real solution is engaging in a lifestyle that builds up the immune system in an effort to fight infections the natural way. Regular exercise (not too long or endurance exercise) with somewhat intense workouts including resistance training can help stimulate the immune system and fight infections and cancer.5–7

Avoid diabetes and limit carbohydrate and sugar consumption, as high blood sugar can lead to decreased immune function and more infections.8 Avoid chronic stress, as it leaves us more susceptible to infections,9 and replace it with acute stresses like workouts and strong experiences.

Also, many vegetables serve as food for our bowel bacteria, and many food sources like kimchi, unpasteurized sauerkraut, and raw dairy contain bacteria.

So, do antibiotics cause cancer?

It is difficult to say if antibiotics can directly cause cancer but obvious to see that that they leave the body in an unnatural and inflammatory state that could decrease its ability to fight cancer. This of course can ultimately lead to cancer.

But, let’s build up our own immune systems to fight disease and infection and not take the chance. Instead of destroying your natural bowel bacteria with harmful antibiotics, feed them, nurture them, and replenish them.

To Your Health,

Dr. Colin Champ

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1. Viaud S, Saccheri F, Mignot G, et al. The intestinal microbiota modulates the anticancer immune effects of cyclophosphamide. Science 2013;342(6161):971-6. doi:10.1126/science.1240537.

2. Iida N, Dzutsev A, Stewart CA, et al. Commensal bacteria control cancer response to therapy by modulating the tumor microenvironment. Science 2013;342(6161):967-70. doi:10.1126/science.1240527.

3. Velicer CM, Lampe JW, Heckbert SR, Potter JD, Taplin SH. Hypothesis: is antibiotic use associated with breast cancer? Cancer Causes Control 2003;14(8):739-747. doi:10.1023/A:1026323424792.

4. Clemente JC, Ursell LK, Parfrey LW, Knight R. The impact of the gut microbiota on human health: an integrative view. Cell 2012;148(6):1258-70. doi:10.1016/j.cell.2012.01.035.

5. Harmer AR, McKenna MJ, Sutton JR, et al. Skeletal muscle metabolic and ionic adaptations during intense exercise following sprint training in humans. J. Appl. Physiol. 2000;89(5):1793-1803. Available at:

6. Pedersen BK. Exercise-induced myokines and their role in chronic diseases. Brain. Behav. Immun. 2011;25:811-816. doi:

7. Pedersen BK, Bruunsgaard H. How Physical Exercise Influences the Establishment of Infections. Sport. Med. 1995;19(6):393-400. doi:10.2165/00007256-199519060-00003.

8. Gan Y-H. Host susceptibility factors to bacterial infections in type 2 diabetes. Miller V, ed. PLoS Pathog. 2013;9(12):e1003794. doi:10.1371/journal.ppat.1003794.

9. Elenkov IJ, Chrousos GP. Stress Hormones, Th1/Th2 patterns, Pro/Anti-inflammatory Cytokines and Susceptibility to Disease. Trends Endocrinol. Metab. 1999;10(9):359-368. doi:10.1016/S1043-2760(99)00188-5.


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