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.

Stomach cancer is not uncommon, with around 15,000 new cases per year on the list of carcinomas. 9,300 men and 5,600 women are affected. The cause of the gender difference is currently unknown.

Stomach cancer is not one of the most common cancers, but the chances of survival are not good. Two thirds ultimately die of the tumor disease. “We have to assume that three out of four patients will only be diagnosed in a locally extended or even metastatic situation,” reports Michael Stahl, head of the Clinic for Internal Oncology at the Evangelical Clinics Essen-Mitte (KEM).

This late diagnosis means that three quarters of the patients have a poor prognosis and cannot be cured with an operation alone, summarizes the oncologist, who is among other things the author responsible for the German guideline for the diagnosis and treatment of esophageal cancer and a member of the lead group of the working group for internal oncology for carcinomas of the stomach and esophagus.

Cause of stomach cancer unknown but there are risk factors

“The only good relative risk factor for stomach cancer is the stomach germ Helicobacter pylori”, the expert clarifies. That would be risk factor number 1.

However, around a quarter of Germans are infected with this bacterium, but only a fraction of them develop gastric cancer. Why they get sick is not yet fully understood, just as much is still unknown about the causes of stomach cancer.

There is also evidence that smoking increases the risk. And what about alcohol? “However, there is no meaningful evidence that alcohol also increases the risk of stomach cancer,” adds the oncologist. However, it can lead to gastric mucosal inflammation, i.e. gastritis, up to and including gastric ulcer (ulcer).

Chronic gastric mucosal inflammation and reflux disease could in turn increase the risk of stomach cancer at the junction with the esophagus.

Stomach cancer can also develop from previous operations on the stomach.

The reflux of bile is also considered a risk factor. This danger arises from being very overweight.

And on the subject of obesity and nutrition: Scientists assume that a one-sided diet with a lot of processed meat products, heavily salted, but also smoked and grilled foods promote stomach cancer – keyword nitrosamines, which are known to be carcinogenic. Rotten and moldy foods pose a general health risk, also with regard to stomach cancer.

Stomach cancer with certain genetic changes

In addition, there are genetic components in the development of gastric cancer: first-degree relatives (children, siblings) of patients with gastric cancer have an increased risk – i.e. if the father, mother or sibling are ill. In addition, stomach cancer can occur if a certain form of colon cancer is already present (hereditary colorectal cancer) or breast cancer.

These are patients with changes in their genetic makeup, for example what is known as microsatellite instability (MSI). You are at an increased risk of various types of cancer, including cancer of the stomach and intestines. “Doctors should keep this in mind if a patient has a colon cancer with microsatellite instability , or if there are multiple carcinomas in the family,” emphasizes the Essen-based oncologist.

However, all of these are only possible risk factors. “Of most patients who fall ill, we don’t know why, because none of these risk factors apply to them,” summarizes Michael Stahl.

Look out for these warning signs

Besides this, there is the second difficulty in gastric cancer – late diagnosis. This is because the symptoms are rather unspecific, affecting the stomach, but are often dismissed as harmless everyday complaints. Early signs can be:

• Feeling of fullness, pressure in the stomach
• general upper abdominal discomfort
• Eructation
• nausea
• Vomit
• Flatulence
• Loss of appetite

“Anyone who has one or more of these complaints for more than three weeks should have them checked out by a doctor,” advises Michael Stahl.

Do not treat persistent stomach problems with acid blockers on your own initiative

However, many sufferers do not take these symptoms seriously and try to relieve them first with self-medication – wasting valuable time on early cancer therapy and thus a high chance of recovery.

They resort to gastric acid blockers that are available over the counter or prescribed by doctors. The pain will actually go away. “Cancer itself does not cause the pain at the beginning of the disease, rather the mucous membrane defect it causes is irritated by stomach acid – and that triggers the pain,” explains the expert.

This pain disappears when the stomach acid is blocked because it no longer irritates the mucous membrane. The cancer growth is not influenced by this, the tumor can spread undisturbed.

The most important diagnostic tool – gastroscopy

The oncologist therefore urgently recommends that the complaints be clarified by a quality-assured endoscopy, i.e. in a gastroenterological practice that carries out these examinations on a daily basis or in an appropriate center.

The gastroscopy only takes a few minutes; the doctor can not only check the condition of the esophagus and stomach up to the duodenum, but can also test whether Helicobacter is present and possibly take additional tissue samples.

Usually no tumor is discovered, but rather the stomach germ or an enlargement or relocation of the area between the stomach and esophagus (hernia), which can cause reflux. A change in diet can help here or medication may be necessary. Sometimes, however, the doctor finds stomach cancer, “and more and more often in the transition area to the esophagus,” reports the expert from the practice.

The reason for this is that there are more and more people who are very overweight. “Being overweight puts pressure on the abdominal cavity, which is why bile acids and stomach acids flow back into the transition area to the esophagus, which is not designed for frequent contact with these acids and is therefore damaged,” says Michael Stahl, summarizing the chain of reactions.

How stomach cancer spreads

The treatment depends on the severity of the disease (grading):

• Whether the carcinoma is limited to the mucous membrane,
• already affects the underlying muscle
• in addition, the outer connective tissue of the stomach
• surrounding organs
• Lymph nodes
• Has metastasized.

In Asian countries, where the risk of stomach cancer is very high and gastric cancer screening is therefore carried out regularly, the cancer can often be detected early. If the diagnosis “stomach cancer” is made in the early stages, i.e. only the mucous membrane is affected, there is a high chance of recovery.

Unfortunately, this is extremely rare in Germany, explains the oncologist. In this country, stomach cancer is usually only discovered when it has worked its way deeper into the tissue or has already broken through the stomach. This is also the reason why the prognosis for stomach cancer in Germany is so unfavorable – the cancer is recognized very late.

Stomach cancer does not depend on age

How long the time span between gastric cancer in its initial stage and the appearance of metastases cannot be answered. However, Michael Stahl points out in this context that it is a cancer myth that the tumor only grows slowly in the elderly. “We also have elderly patients with rapidly growing stomach cancer, and young ones,” he warns. Young people should also take stomach problems seriously and not dismiss them: “I’m only 35, it can’t be something bad, like cancer.”

Treatments for stomach cancer – chemotherapy plus surgery

Only in the early stages, i.e. when stomach cancer is limited to the mucous membrane, surgery alone is the method of choice. Then it is the only way to cure the patient.

Most patients, however, need more than the operation, the scientist reports. For locally advanced tumors (without metastasis), treatment consists of chemotherapy, surgery and renewed chemotherapy. Chemotherapy before the operation is intended to shrink the tumor and combat (invisible) metastases at an early stage.

Antibody therapy for HER2-positive gastric cancer

In addition, chemotherapy plus antibody therapy with so-called HER2 antibodies is used for certain forms of metastatic gastric cancer. In around 20 percent of gastric cancer patients, HER2 receptors (HER2-positive gastric cancer) are found in particularly large numbers on the cancer cells. They are docking points for growth factors. Occupied by the special antibodies, tumor growth can slow down significantly.

By the way, HER2 receptors are also found on breast cancer cells, keyword HER2-positive breast cancer. This is where this antibody therapy, which incidentally does not count among the immunotherapies, was first used.

In addition, attempts are being made in Germany, the scientist reports, to treat HER2-positive gastric cancer with HER2 antibodies plus immunotherapy. Scientists hope that this will enable them to offer equivalent treatment without chemotherapy in the future. However, the effect of this combination of therapies has not yet been proven.

Immunotherapies for gastric cancer do not (yet) meet expectations

In some forms of cancer such as melanoma or lung cancer, immunotherapies, for example with checkpoint inhibitors, are considered particularly successful today. These drugs are also currently being tested in studies for gastric cancer .

“Unfortunately, the first results are sobering,” reports the scientist. He and his colleagues had hoped that immunotherapy could improve the effect of chemo, but this was not confirmed. “If, however, all therapy options have already been exhausted in a patient, more can be achieved with immunotherapy than without further tumor-specific treatment,” reports Michael Stahl about the studies.

The problem with this is that it is currently difficult to predict in which patients the immunotherapy will work and which will not. Only in the few patients (less than ten percent of all patients with gastric cancer) whose tumors show what is known as high microsatellite instability (MSI-H) can one predict that immunotherapy has a high chance of effectiveness. Overall, the risk of severe side effects under immunotherapy is significantly lower than under chemotherapy, namely 20 percent instead of 60 percent.

The prognosis for gastric cancer is poor because the patients are late

How successful are the therapies at a glance? “The chances of a cure for stomach cancer are on average 25 to 30 percent; if stomach cancer is metastatic, the average life expectancy is one year,” reports Michael Stahl. The prognosis is only very good at a very early stage. However, patients with gastric cancer in this easily curable stage would be the exception in practice because many go to the doctor too late.

Prevention of stomach cancer – three measures

This makes provision and prevention all the more important. This includes, on the one hand, having longer stomach complaints clarified by a gastroscopy – and it does not matter how old the person affected is.

On the other hand, everyone should pay attention to the following three factors. Because little is known about the development of stomach cancer, so few are:

1. Pay attention to food hygiene, do not eat spoiled food, nothing that is moldy
2. Do not smoke
3. Avoid being overweight

This can not only protect the stomach, but is known to promote general health – not smoking and maintaining a normal weight are among the most important preventive measures against cardiovascular diseases such as high blood pressure, heart attack and stroke, but also against cancer.