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  • Yuzo Endo, M.D., Ph.D.
  • Masahito Hitosugi, M.D., Ph.D.
  • John E. Lewis, Ph.D.

Doctor’s Health Advice

Doctor’s Health Advice

Pathologist’s advice on how to combat cancer


Defense strategies against colorectal cancer

Colorectal cancer rises as our diet becomes westernized

Let us focus on colorectal cancer as we examine some of the defense strategies we can employ against cancer. I have chosen colorectal cancer because it is most intimately linked with food. Colorectal cancer (a cancer of the large intestine) is truly a lifestyle-related disease; the incidence of colorectal cancer has risen in both men and women in Japan as our diets became more westernized.

Furthermore, new medical evidence has given us clues on how to prevent colorectal cancer. That is, the chances of developing colorectal cancer can be reduced by maintaining a healthy large intestine using medications that reduce inflammation.

The large intestine extends upwards from the lower-right side of the abdomen to the upper abdominal area, traverses to the left side, descends to the lower left side of the abdomen, and ends at the anus. The total length of the large intestine is about 1.5 meters. Water in food matter is gradually absorbed while it moves through the large intestine, and the food residues are accumulated and solified in the lower left side of the abdomen, particularly in the rectum. That is why you can sometimes feel the accumulated food matter in the lower left area when you feel your abdomen. On the right side of the abdomen and in the upper abdominal area, food matter is still in a liquid or semi-solid form. This food matter is gradually pushed towards the lower left area by the muscular movements of the large intestine.

Cancer prevention: Preventing epithelial cells from becoming cancerous

The food matter in the large intestine is called feces in simplistic terms, but the amount of fat or protein it contains varies greatly depending on which portion of the large intestine the food matter is moving through. The passage time of the food matter and its effect on the large intestine has been a subject of interest.

When a colonoscope is used to look inside the large intestine, a soft mucous membrane lining the internal wall can be seen, and the large intestine looks like a pink tube. When the wall of the pink tube is magnified using a microscope, one can see fine, deep folds that are tightly organized. It is due to these folds that the large intestine can have an immense area of contact with the contents that pass through it. The surface of these folds of the mucous membrane is covered with an epithelial layer, which contains a row of tube-like projections. The epithelial cells absorb nutrients and water, and secrete digestive enzymes and mucus that facilitate the movement of the intestinal contents.

These epithelial cells, which are in direct contact with the intestinal contents, can become cancerous. To prevent cancer, we must prevent epithelial cells from becoming cancerous. Certain things we eat can cause these epithelial cells to become cancerous, while other foods are gentle and soothe the epithelial cells.

The immune system of the intestine is the driving force behind the power of natural healing

The contents of the large intestine are not entirely food material. The large intestine is originally inhabited by an enormous amount and variety of intestinal bacteria. Maintaining a good balance of intestinal bacteria is important for maintaining a healthy body. Even though intestinal bacteria are lost together with food matter during the excretion of feces, their population grows back again through multiplying, forming unique bacterial colonies inside the intestines.

These intestinal bacteria are first acquired at birth, during the baby’s passage through the mother’s birth canal. When you are thinking about the relationship between the intestinal contents and the wall of the large intestine, it is important that you give enough thought to not only the food, but also the bacteria, in the intestines. The wall of the intestines has immune functions, which function like a breakwater that protects the coast, and this is called the intestinal immune system.

The presence of intestinal bacteria helps to regularly maintain the entire body’s immune functions. In other words, we can think of the intestinal immune system as the driving force behind the power of natural healing. Three factors comprised of the intestinal mucous membrane, the intestinal contents, and the intestinal bacteria, interact in complex ways to trigger not only colorectal cancer and inflammatory diseases of the intestines (such as ulcerative colitis and Crohn’s disease), but also many other diseases that affect different parts of the body.

The relationship between dietary fiber and colorectal cancer

As I have mentioned in my previous articles, cancers have a latency period. The latency period of colorectal cancer is at least 10 years, and close to 20 years, before the cancer becomes visible to the eye. About 50 years have passed since the mid-1950s, which was when the economic situation improved in Japan, and people started incorporating Western foods into their diets. The incidence of colorectal cancer started rising approximately 20 years later, suggesting that during this time, this lifestyle-related disease was in its latency period. Colorectal cancer is an adulthood cancer. Aside from a rare inherited disease called familial adenomatous polyposis, which can lead to colorectal cancer, I have never heard of a single case of colorectal cancer in children.

You have probably heard of the term “polyp.” A polyp is a growth that projects from a mucous membrane that has a “head” portion, somewhat resembling the cap of a mushroom. The epithelial cells of the “head” portion can often progress to cancer, so polyps are removed during colonoscopy, or in some cases a small sample of the polyp is removed for pathological testing (biopsy). Colorectal cancer can either progress from a polyp or from a lesion that originally forms as a shallow depression.

As I have mentioned earlier, it is the role of the pathologist to examine such areas under a microscope and to determine whether or not they are cancerous. Cancer is not confirmed based on endoscopic examinations and X-rays. The diagnosis always involves a pathological examination of the tissue as well as a pathology report, which is an official documentation of the findings. If a pathological examination is conducted when you have an endoscopic examination, I recommend that you ask the medical institution to give you the pathology report for your personal record so that you can seek a second opinion based on this report.

The causes of colorectal cancer lie in the Western pattern diet

The development of colorectal cancer is not equally common across the full length of the large intestine. In the Japanese population, about three quarters of all cases of colorectal cancer are found around the lower left part of the abdomen. It is often concentrated in the rectum. This trend is generally the same in other countries, though in developed countries, cancer has also been found to develop in other areas of the large intestine. This general trend suggests that the long period of contact between the solidified contents and mucous membrane of the rectum increases the likelihood of developing cancer.

The fact that cancer occurs in other areas of the large intestine in developed countries may suggest that foods in Western pattern diets contain more factors that cause cancer. Red meats such as beef and pork, burnt portion of those meats, the fat in dairy products and bile that tries to break down the fat, and metabolites produced by intestinal bacteria are considered to be possible sources of carcinogens. These foods and substances are therefore thought to be intricately linked to the onset of colorectal cancer.

A relationship between dietary fiber and colorectal cancer was first reported in an investigation conducted by a British surgeon named Dr. Denis Burkitt, in South Africa. In the local people who consumed potatoes and other root crops as a staple food and who could not consume meat, virtually no cases of colorectal cancer, intestinal polyps, diverticulosis, or gallstones were found-however, these diseases were common in England. This finding suggests that certain foods, particularly foods that are rich in dietary fiber, may be preventing those diseases.

Predisposition to colorectal cancer (Risks)

The reality is that colorectal cancer is often discovered too late in clinical practice. The reason for this is because there are few symptoms that we can notice ourselves (subjective symptoms). In many cases, the cancer is already in advanced stages when people experience subjective symptoms such as diarrhea or constipation. However, since colorectal cancer develops slowly, if there are no abnormalities found after a careful endoscopic examination it is not necessary to take the test annually as part of your regular medical check-up.

A thorough check-up every few years is sufficient for starting treatment, if necessary. The fecal occult blood test, which tests for traces of blood in the stool, can be easily done and is effective to an extent. However, it is not adequate for detecting early stage cancers. This brings up an important point: How do we detect colorectal cancer early? Firstly, we must realize whether or not we are prone to getting colorectal cancer.

There are several characteristics that make a person more prone to developing colorectal cancer (risk factors). These include: having a family member with colorectal cancer; a predilection for beef, pork, dairy products and eggs; disliking fruit and vegetables; and being a smoker. If any of these apply to you, I recommend that you have a colonoscopy once you reach the age of 50, even if you do not have any subjective symptoms. According to some studies, a small percentage of such people (who have the above characteristics) would have developed cancer by this age. Naturally, those people who are at low risk often have the opposite characteristics as those listed above. Nevertheless, even those at low risk should undertake a thorough endoscopic examination, to have their own peace of mind.

Chronic inflammation promotes cancer

Recent studies have shown that regular users of analgesics such as aspirin are less likely to get cancer in general, including colorectal cancer; this finding has been attracting some attention. Aspirin, however, has several side effects, so please do not immediately follow this practice after reading my article. Drugs that are better suited for this purpose have been developed, and the use of such drugs to reduce inflammation as well as to prevent cancer has been studied. Aspirin has an effect of reducing inflammation and relieving pain. It is believed that aspirin also exerts these effects on the mucous membrane inside the large intestine. The chance of developing colorectal cancer increases when the large intestine is inflamed for a long period of time (chronic inflammation) as a result of diseases such as ulcerative colitis and Crohn’s disease.

Chronic inflammation is a key factor in the progression of cancer. There are many things we can do to alter the contents of our intestine and make the mucous membrane healthy. Yoghurt made from soybean, calcium, sources of dietary fiber such as boiled vegetables and vegetable salad, and probiotics (which have been popular recently) are some of the foods that are currently in the spotlight. BioBran, which has shown diverse effects including anti-inflammatory effects, is another health food that is anticipated to not only assist in the treatment of colorectal cancer, but is also effective in the prevention of cancer relapse.

The concept of coexisting with cancer rather than eradicating cancer

In contemporary medicine, treatment with anticancer agents is the first choice treatment or the only available treatment for advanced colorectal cancer. However, the treatment effect of anticancer agents on colorectal cancer varies greatly depending on each individual patient because of the difference in characteristics of the individual’s cancer, such as the ways in which it spreads, or the speed of its growth. Therefore, we cannot expect anticancer agents to have the same clear-cut effect as antibiotics. Anticancer agents also cause serious adverse effects. In other words, there are infinitely many ways to select an appropriate treatment method for each person.

Many new treatment methods have been developing in recent years. These include immunotherapy, endovascular therapy, hyperthermia, and cocktail treatment using herbal medicine or Chinese medicine. In cases where there are no treatments that are particularly effective for that patient, I believe it is a matter of gradually finding treatments that have at least a slight effect, and adding such treatments to the patient’s treatment regimen, step by step. During this process, it is important to shift our focus away from eradicating cancer; rather, we should focus on slowing down the speed of cancer progression by even a little bit, or on coexisting with cancer. First and foremost, this requires the patient and the treatment provider to have a tremendous level of trust in their relationship. I believe that by following through with a selected treatment and not giving up, patients can expect a longer survival period.

Finally, let me touch upon the greatest mystery in medicine pertaining to cancer of the digestive tract. As we have discussed, the large intestine is vulnerable to cancer. The mystery is that, in adults, cancer never affects the small intestine, which is about three times longer than the length of the large intestine. Many hypotheses for this phenomenon have been put forth, but no compelling medical evidence has been found. It remains a medical mystery of the 21st century. If we can find out why cancer does not develop in the small intestine, I believe it would give us clues as to how colorectal cancer can be prevented-don’t you think?

In the next article, we will examine some of the defense strategies we can employ against stomach cancer.


Yuzo Endo, M.D., Ph.D.

Yuzo Endo, M.D., Ph.D.
Hamamatsu University School of Medicine

1969.9: Graduated from Medical School, University of Tokyo Consultant pathologist in Hamamatsu University, Medical School, and Fujimoto General Hospital. Medical Consultant in conventional and integrative medicine.

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