Small bowel cancer accounts for up to five percent of all bowel cancers; around 2,600 men and women were diagnosed with small bowel cancer in 2016, compared with around 60,000 colon cancer. “It is important to classify a carcinoma on the one hand by localization, i.e. in the case of bowel cancer, small or colon cancer, but also differentiate it on the basis of its biological characteristics,” reports Ulrich Graeven, chief physician at the Clinic for Hematology, Oncology and Gastroenterology at Maria Hilf Mönchengladbach Hospital.

Cancer of the small intestine is usually biologically very different from cancer of the colon

While colon cancer is usually adeno tumors, i.e. growths of the mucous membrane, this affects only a small fraction of small bowel cancer. The most common forms of small bowel cancer, depending on the cells that cause the disease, are:

• Neuroendocrine tumors (NET) with around 50 percent, they arise from hormone-producing cells
• Gastrointestinal stromal tumors (GIST) make up about ten percent, these tumors originate from the connective tissue in the gastrointestinal tract.

The differing biological characteristics of the two types of colon cancer, colon and small bowel cancer, “make these two diseases so fundamentally different, even though both affect the bowel,” explains the oncologist.

Causes of small bowel cancer and why it is less common than colon cancer

What triggers the fact that the cells in the small intestine no longer act normally, but degenerate and multiply in an uncontrolled manner, is still largely unknown. It is assumed that there is a connection with pollutants in food that come into contact with the small intestine during passage and can thus influence its cells.

It is well known that the small intestine connects directly to the stomach. This first section of the three-part small intestine is called the duodenum, followed by the jejunum and ileum. In addition to transporting the chyme to the large intestine, the task of the five-meter-long small intestine is to break down certain food components and release them into the blood. The most important ones are carbohydrates, which are processed into various sugars, fat, but also vitamins and trace elements.

The chyme is still thin in this section of the intestine and is therefore transported on quickly. The contact time with the intestinal wall is much shorter than later in the large intestine, “which could explain why colon cancer is much more common than small intestine cancer,” the gastroenterologist explains the possible background. In addition, the mucous membrane in the small intestine is less susceptible to certain factors such as pollutants than that in the large intestine.

Risk factor hereditary diseases

However, there is also a familial willingness to develop small bowel cancer: Hereditary polyposis syndromes such as familial adenomatous polyposis (FAP) and Lynch syndrome. Genetically, a large number of polyps develop in the large intestine, sometimes also in the small intestine. These are adenocarcinomas, but are very rare in the small intestine compared to NET and GIST.

Small intestinal tumors associated with FAP are usually only discovered when polyps have been detected in the large intestine. In the course of further diagnosis of the familial predisposition, these rare small bowel carcinomas are also identified.

Small bowel cancer symptoms

Small bowel cancer usually grows slowly. Frequently, signs only appear when the disease has progressed and the tumor is taking up space. Depending on you can

• Bleeding,
• Stomach pain,
• nausea
• Constipation or diarrhea

occur. If the tumor is large, it can even block the intestines (ileus). The intestinal obstruction manifests itself through massive pain, it is always a medical emergency that is life-threatening and must be treated immediately.

Small bowel cancer prognosis varies

Small bowel cancer is usually only discovered at an advanced stage. In more than 70 percent, the carcinoma is only diagnosed in stage three or four, i.e. later than this applies to this common colon cancer – again the comparison with colon cancer.

The survival rates for small bowel cancer are therefore somewhat lower. “The decisive factor, however, is always the type of cancer of the small intestine,” explains the expert. If a GIST or NET is detected early, the chances of survival are very good. If, on the other hand, it is adenocarcinoma, which is also usually discovered later, the prognosis is not quite as favorable.

Diagnosis of small bowel cancer

The classic examination methods of gastroscopy and colonoscopy only cover the upper or lower part of the small intestine, “the almost five meters in between are not reached with these examination techniques,” explains the expert.

Imaging methods such as magnetic resonance tomography (MRT) or computed tomography (CT) are only used if there are symptoms and suspicion of this intestinal tumor. Capsule endoscopy, which shows images from the small intestine, also provides information.

Only when these examinations reveal an abnormality is it possible to specifically mirror the small intestine. “However, this is very time-consuming and cannot be used as a preventive examination – also because these intestinal tumors are very rare,” emphasizes Ulrich Graeven.

Small intestinal cancer therapies – surgery and its consequences

Overall, the following applies to the various small intestinal tumors: If possible, an operation should be performed. “If the tumor is limited, parts of the small intestine can usually be removed without any problems,” explains the oncologist in more detail.

A stoma, i.e. an artificial anus, is therefore usually not necessary. However, it is crucial which part of the small intestine is missing and which functions it had, which trace elements and vitamins it passed on to the body. This deficiency must then be compensated for through appropriate nutrition or medication.

Treatment for small bowel cancer varies depending on the type of tumor

Parts of the removed tumor are examined histologically. For the therapy plan, it is crucial whether it is NET, GIST or the rare familial adenocarcinoma in the small intestine. “A generally applicable therapy scheme for small bowel cancer is not possible because there is not just one small bowel cancer, but different ones, it always depends on its type,” emphasizes the oncologist.

Accordingly, there are many different therapy options. If a gastrointestinal stromal tumor (GIST) has metastasized, for example, there are very good drugs for further treatment. “This is not the classic chemotherapy, but we use so-called tyrosine kinase inhibitors, with very good results,” reports the expert. These are inhibitors, such as imitanib, that can block certain signaling pathways within the cells. They are sometimes also used before an operation to reduce the size of a tumor that is too large and therefore inoperable, or after an operation to avoid a relapse.

If the cancer of the small intestine is a neuroendocrine tumor (NET), on the other hand, surgery is often the only treatment required. The NET is further subdivided with regard to the need for drug therapy, taking into account its growth rate. This subdivision of the NET is also of crucial importance for planning therapy for metastatic NET.

Ademocarcinoma of the small intestine is treated on the basis of the results from the treatment of colon tumors.

Small bowel cancer prevention

Targeted prevention against these rare tumors is hardly possible – apart from the well-known rules for a healthy life, i.e. without smoking, with a sensible diet, extensive alcohol restriction and sufficient exercise. Because little is known about the possible causes of small bowel cancer, they cannot be influenced.

However, there is an important tip from the expert for everyone in whose families there are genetically determined polyps in the large intestine: Remember to not only limit the preventive measures to the large intestine, but also to extend it to the small intestine. Although this is provided for in the relevant colorectal cancer screening and follow-up programs, it must not be overlooked.

The latest news from German slaughterhouses have certainly given the vegetarians and vegans community a new boost. In addition to animal welfare and ecological aspects, avoiding meat is usually also based on the desire for a healthy diet. What does science say

1. Consensus: little meat is okay, but not really necessary

Every German eats 150 grams of meat and meat products on average every day. That doesn’t sound like a lot, but it clearly exceeds the maximum 600 grams that the German Nutrition Society per week finds acceptable. Many consumers are also significantly higher. It is these “meat eaters” who are mentioned in the studies on the harmful effects of meat consumption.

But even with those who eat a lot of meat, there are differences: because those who eat a lot of unprocessed meat, and at the same time high in fiber and low in sugar, have a low risk of disease. This is the case, for example, with the Paleo diet.

Experts consider the Mediterranean diet to be the best nutritional method in the world, and it has been for two decades. In 2019 she was once again named the best diet of the year by “US News” . A lot of vegetables, fish and olive oil end up on the plate, but little meat and processed foods.

In comparative studies, it is not vegetarians and vegans who do well, but people who eat little meat.

But you can also say with a clear conscience to Tilmann Kühn, nutritional epidemiologist at the German Cancer Research Center (DKFZ) in Heidelberg: “If you eat wholesome vegetarian food, your body is fine. On the contrary, according to scientific findings, a vegetarian diet is actually very healthy. ”With one small caveat:“ Less meat ”only makes sense if the calorie advantage is not topped up with pizza, biscuits or meat imitations.

2. Those who do not eat meat also live more healthily in other ways

Numerous studies have shown that the biggest meat fans usually do not have good eating habits. Even if you neglect the nutritional value of individual foods, a diet high in meat and sausage as well as sugar, white flour and saturated fats from ready-made foods is unhealthy. Because healthy foods such as vegetables, fruit, legumes, whole grains or nuts are definitely neglected.

3. meat or plant? Nutritional studies are conditionally meaningful

In the laboratory, it is possible to determine how certain nutrients affect human cells. Studies with humans don’t work like that. The health comparison “meat eaters versus vegetarians” is only possible in observational studies. Their conclusions are only an approximation of reality. Too many factors play a role in health for the question to be reduced to schnitzel and tofu . For example: is a chain-smoking vegan healthier than an athletic meat eater?

Epidemiological studies can never conclusively prove that meat consumption is unhealthy. And it is also not conclusively clear which individual ingredients are harmful to health.

4. When it comes to meat, it depends on the color

Beef, pork, lamb or sheep provide the so-called red meat. It is said to cause cardiovascular diseases and problems with the blood vessels.

For US researcher Stanley Hazen from the Cleveland Clinic, a metabolic product of the carnitine contained in red meat is responsible for this. To prove this, he had 113 test subjects eat 250 grams of steak a day for four weeks. A two-week break was followed by four weeks with a correspondingly large amount of (white) poultry meat and, at the end, a meat-free month.

The result , published in the “European Heart Journal”, showed a significant 3-fold increase in the TMAO plasma concentration during the steak weeks. TMAO is produced during the metabolism of carnitine and is a risk marker for hardening of the arteries in the blood vessels. The diet with poultry and vegetables led to a decrease in plasma concentrations in the test subjects.

Red meat is also directly or indirectly involved in the development of cancer.

For example, studies by the DKFZ have shown that people who eat a lot of red meat have increased biomarkers of certain roasting substances, such as those produced during roasting and grilling, swim in the blood. These people were at an increased risk of developing colon cancer.

In the large-scale EPIC study across Europe, 519,000 test persons were examined to find out the connection between diet and cancer .

The results show that red meat can increase the risk of colon cancer. Accordingly, the risk of the disease increases by almost 50 percent if the daily consumption of meat is 100 grams above the recommended amount. The same amount of sausage products increases the risk by as much as 70 percent.

The risk of stomach cancer is also said to be related to heavy meat consumption. In people infected with the Helicobacter pylori bacterium, the risk increases by a factor of five.

5. Theory 1: Iron makes meat unhealthy

There are various theories about why red meat is so problematic. The so-called iron load hypothesis is based on the fact that red meat contains a comparatively high amount of iron. This so-called heme iron has a high bioavailability, unlike iron from plant food, and thus enters the organism in larger quantities.

It has long been suggested that high levels of iron in the blood increase the risk of cancer . However, this theory has not yet been proven by studies.

6. Theory 2: BMMF make meat unhealthy

Scientists working with Nobel laureate Harald zur Hausen believe they have found another cause: a previously unknown class of pathogens is responsible for the increased risk of colon cancer .

These “Bovine Milk and Meat Factors (BMMF)” enter the human intestines through the consumption of meat and dairy products from European cattle. There it comes to a chronic inflammation, which indirectly promotes the development of colon cancer.

7. Avoiding meat protects the intestines

Vegetarian foods contain fiber, which has a positive effect on the microbiome in the gut. Vegans have a particularly large number of them. In addition to fruit and vegetables, lactic acid foods such as yogurt also support the intestinal flora. Vegetarians often consume these. Researchers from the University of New York have confirmed that vegans and vegetarians have more protective types of gut bacteria than meat eaters.

Meat also poses a cancer risk through its preparation and processing: for example, when meat is heated up, several potentially harmful substances are formed at the same time, including so-called polycyclic aromatic hydrocarbons (PAHs); curing also produces nitrosamines. These substances can promote the development of cancer, and above all they increase the risk of colon cancer. Methods such as curing and intense heating are particularly used for industrially processed meat, such as sausage and ham. Accordingly, processed meat products are particularly unhealthy.

8. Avoiding meat makes you slim

Researchers at the Max Planck Institute for Cognitive and Neurosciences (MPI CBS) and the Leipzig University Hospital examined almost 9,000 people, what connections there are between body and mind on the one hand and not consuming animal products on the other. regardless of age, gender and level of education. The study was published in June 2020 in the specialist magazine “Nutrients”.

The result of the physical impact: the less food of animal origin was on the menu, the lower the average body mass index (BMI) and thus the body weight. “Products that are excessively high in fat and sugar make you fat. They stimulate the appetite and delay the feeling of satiety. If you do without animal foods, you eat fewer such products on average, ”explains Evelyn Medawar, first author of the work.

9. Avoiding meat and the psyche

With regard to the psychological effects of the meatless diet, the Leipzig study found no particular susceptibility to neuroses in vegetarians. The study director Veronica Witte says: “Previous analyzes had found that more neurotic people generally leave out certain food groups more often. We focused solely on avoiding animal products and could not observe any correlation. ”No connection was found between a predominantly plant-based diet and depressive moods. There was evidence of this in previous studies.

However, the researchers found a difference in one of the determining factors of personality: the extroversion or introversion. People with predominantly plant-based foods on the menu are more introverted than those who eat primarily animal products. The study authors have not yet found an explanation for this.