Generality
Stomach cancer, or gastric tumor, is the neoplasm - of a generally malignant nature - that develops from a "mad cell" of the stomach.
More common in the older age group, this serious disease is the fifth most common form of malignancy and the third most common cause of cancer death after lung cancer and liver cancer.
The precise causes of stomach cancer are unknown; however, the doctors agree that, on the development of gastric neoplasms, they surely affect: a wrong diet, cigarette smoking, genetic factors, gastric ulcer, Helicobacter Pylori infection, pernicious anemia, autoimmune atrophic gastritis, alcohol abuse and consumption of foods contaminated with aflatoxins.
After an initial asymptomatic phase, stomach cancer causes digestive disorders and general symptoms, which tend to progressively worsen with advancing disease.
Accurate diagnosis of gastric cancer requires several investigations; a very important diagnostic test is gastroscopy.
Stomach cancer therapy may include: surgery, chemotherapy, radiotherapy and so-called targeted therapy.
Brief anatomical recall of the stomach
The stomach is the organ of the digestive system within which the foods ingested at the level of the mouth are collected and within which the digestion of proteins and carbohydrates takes place.
About 25 centimeters long and protected by the peritoneum, the stomach resides between the esophagus and small intestine (or small intestine ): to separate it from the first, is a valve called cardias ; to separate it from the second, however, is a valve known as the pyloric sphincter .
Cardias and pyloric sphincters regulate the passage of food (called more properly bolus ) among the compartments that separate, therefore: esophagus-stomach, as far as the cardia is concerned, and stomach-small intestine, as regards the pyloric sphincter.
In this brief review of the anatomy of the stomach, the stomach wall (or gastric wall ) is also worth mentioning; the latter presents 3 fundamental cellular layers (or cassocks) which, proceeding from the outside towards the inside, are:
- The serous tunic . It is the covering layer and, in fact, is part of the peritoneum adhering to the stomach.
- The muscular habit . It is the layer composed of oblique, longitudinal and circular muscle fibers.
- The mucous membrane . Composed of epithelial cells, glands and smooth muscle fibers, it is the layer appointed to:
- the production of acidic gastric juices, necessary for the digestive process;
- mucus secretion intended to protect the stomach from the aforementioned gastric juices;
- gastrin hormone production.
What is stomach cancer?
Stomach cancer, or gastric tumor, is the neoplasm that develops from a stomach cell.
Are stomach cancer and stomach cancer the same thing?
Since it is almost always a malignant neoplasm, stomach cancer is also called stomach cancer .
However, it should be pointed out that, in general, the word "tumor" indicates a neoplasm regardless of its benign or malignant nature, while the word "cancer" specifically refers to a malignant neoplasm.
Locations of stomach cancer
Gastric cancer can affect any part of the stomach. Therefore, it has no localization preferences, as it happens for example in the case of pancreatic cancer, which mainly affects the pancreatic gland head.
Types of stomach cancer
There are different types of stomach cancer.
Among these types, there is one decidedly more common and important than the others: the so-called adenocarcinoma of the stomach or gastric adenocarcinoma . Representing 90% of gastric cancer cases, this malignant neoplasm originates from the epithelial cells of the stomach mucosa or from the glands interposed between these epithelial cells.
To complete the picture of the various types of stomach cancer (as well as the remaining 10% of clinical cases), they are:
- Gastric lymphoma (or MALT lymphoma ). It is the malignant stomach tumor that comes to life from lymphocytes (cells of the immune system) residing in the mucous membrane of the stomach.
The acronym MALT stands for " Mucosa-Associated Lymphatic Tissue ", which in Italian means "Mucoid -Associated Lymphoid Tissue ". Therefore, MALT lymphoma is the malignant tumor arising from a lymphocyte of the lymphoid tissue associated with the mucous membrane of the stomach.
- Gastrointestinal stromal tumor . It belongs to the category of so-called soft tissue sarcomas and originates from one of the particular cells having the function of regulating the motility of food along the digestive tract; cells with this property are found not only in the stomach, but in all the organs responsible for digestion.
- Gastric leiomyosarcoma . Also falling into the category of soft tissue sarcomas, it originates in a smooth muscle cell of the stomach.
- The gastric carcinoid . Belonging to the category of neuroendocrine tumors (tumors deriving from the cells that produce hormones), it is the malignant neoplasm in the stomach that originates from one of the cells responsible for the production of the gastrin hormone.
What is an adenocarcinoma?
Adenocarcinoma is a particular type of malignant tumor that originates from epithelial cells of the exocrine glandular organs or from epithelial cells of tissues with secretory properties .
Examples of exocrine glandular organs are breast, pancreas or prostate; examples of tissues with secretory properties, on the other hand, are the layers of mucosa that line the inner wall of the airways, esophagus, stomach, colon or rectum.
Adenocarcinomas belong to the large category of carcinomas, malignant tumors that develop from epithelial tissue cells.
Stomach tumors in percentages | |
| Types of stomach cancer | % (percentage) of various stomach cancers |
Adenocarcinoma of the stomach | 90%. It means that 90 out of 100 cases of stomach cancer are gastric adenocarcinomas. |
Gastric lymphoma | 6-7%. It means that 6-7 cases out of 100 of stomach cancer are gastric lymphomas. |
Gastrointestinal stromal tumor | About 1%. It means that only 1 in 100 cases of stomach cancer is a gastrointestinal stromal tumor. |
Gastric leiomyosarcoma | About 1% |
Gastric carcinoid | About 1% |
MACRO- AND MICRO-SCOPE VARIANTS OF THE STAINED ADENOCARCINOMA
From the macroscopic point of view (ie with the naked eye), doctors recognize the existence of 4 variants (or subtypes) of gastric adenocarcinoma, which are:
- The polypoid variant;
- The ulcerative variant;
- The ulcerative-infiltrative variant;
- The infiltrative variant, also known as plastic linite .
From the microscopic point of view (ie under the microscope), instead, the variants of adenocarcinoma in the stomach, recognized by doctors, are only 3:
- The intestinal variant (or well differentiated);
- The diffuse (or poorly differentiated) variant;
- The "castone" cell variant.
In the medical field, the macroscopic classification of gastric adenocarcinoma is called " classification according to Bormann ", while the microscopic classification of stomach adenocarcinoma is called " classification according to Lauren ".
Causes
Despite the numerous researches conducted so far, the precise causes of the aforementioned mutations are unknown; however, studies aimed at identifying them were however found to be useful and important, as they allowed doctors to decipher, with a good degree of security, the risk conditions (or risk factors) of stomach cancer .
Main risk factors for stomach cancer
The main risk factors for gastric cancer include:
- Hereditary risk factors . Reliable genetic studies have shown that hereditary diseases are strongly linked to the development of gastric tumors.
The most famous of these diseases is the condition known as diffuse hereditary gastric tumor, which is characterized by the presence of a mutation, which can be transmitted from generation to generation, to the CDH1 gene.
Located on chromosome 16, the CDH1 gene encodes a protein known as cadherin E (NB: cadherins are fundamental proteins for inter-cell adhesion).
Another important hereditary disease, which drastically increases the risk of developing stomach cancer (even 23 times, according to some research), is Lynch syndrome type II ; this hereditary condition is also known to cause cancers of the colon, a section of the large intestine.
- Nutritional risk factors. Because the stomach is an important collection point for ingested food, its health is highly dependent on what you eat.
After numerous research and clinical observations, doctors and experts in the field of nutrition have concluded that it is harmful to the stomach, and favors the appearance of tumors at the gastric level, a diet with the following characteristics:
- Too much salt to season food and too many salty foods already prepared or preserved in salt (sausages, salted meats, salted fish, certain cheeses, pickled foods, fried in bags, dried fruit in bags, etc.);
- Too many smoked foods (smoked salmon, smoked tuna, smoked meat and salami, etc.);
- Too many foods or beverages rich in carbonized molecules (grilled or grilled foods, caramel, coffee, etc.);
- Too many foods rich in nitrites for their preservation (meats and cheeses);
- Too many foods of animal origin (butter, fatty cheeses, milk cream, egg yolk and fatty meats);
- Too many fried foods rich in margarines and oils of tropical origin subjected to processing (chips in envelopes or fast-food fries, chocolates, sweet snacks, etc.);
- Too many alcoholic beverages;
- Shortage of whole foods (legumes and cereals rich in fiber);
- Shortage of fresh fruit and vegetables, rich in provitamin A, vitamin C and antioxidants;
- Shortage of cold-pressed seasoning oils of vegetable origin;
- Excessive consumption of food stored in plastic bags;
- To learn more, read: Stomach Diet and Tumor
- Membership in blood group A. Observing the spread of stomach cancer in samples of people, whose only parameter was blood type, several research teams noted that the sample of people in blood group A was the one with the highest percentage of patients. Therefore, based on this evidence, they concluded that those belonging to blood group A have a particular tendency, higher than that of those belonging to other blood groups, to develop stomach cancer.
Despite studies on the subject, the reasons behind this particular trend remain unknown.
- Consumption of foods contaminated with aflatoxins . Aflatoxins are mycotoxins produced mainly by two species of Aspergillus, a fungus that lives in geographical areas with a hot and humid climate. Aflatoxins owe their notoriety to their marked carcinogenic and mutagenic power and to the fact that they are frequent food contaminants.
- Gastric polyps . They are tissue growths that grow from the cells of the stomach mucosa. As a rule, they are benign in nature, but, for unknown reasons, they can degenerate and evolve into real malignant tumors of the stomach.
The probability of a malignant evolution of gastric polyps would seem to depend on size: the larger a gastric polyp is, the easier it is to turn into a malignant gastric tumor.
- Autoimmune atrophic gastritis . It is the chronic inflammation of the mucous membrane of the stomach, due to a malfunction of the immune system and resulting in the disappearance of the gastric glands, which are replaced by fibrous tissue and other glands that usually reside in the intestine (intestinal metaplasia).
Example of chronic type A gastritis, autoimmune atrophic gastritis has been shown to be an important condition favoring the appearance of stomach cancer.
- Pernicious anemia . It is the lack of red blood cells due to the failure to absorb vitamin B12 (a fundamental element for the formation of new erythrocytes).
It is an autoimmune disease, which arises from the aggression, by some antibodies, of the stomach cells responsible for producing the so-called intrinsic factor, the glycoprotein necessary for the absorption of vitamin B12.
According to reliable statistical surveys, 6 patients per 100 with pernicious anemia (ie 6%) would be destined, sooner or later, to develop a gastric neoplasm.
For the experts, in people with this particular anemic form, the risk of developing stomach cancer would be 2-3 times greater than the risk of those belonging to the healthy general population.
- Gastric ulcer . It is an erosion, more or less deep, of the gastric mucosa, which is very reminiscent of the lesions left by cigarette butts in contact with the skin.
Possible event but extremely rare (less than 10 patients per 100), the malignant degeneration of a gastric ulcer (ie the passage from gastric ulcer to stomach cancer) concerns above all the cases in which the erosion of the gastric mucosa has large dimensions.
- Infection with Helicobacter Pylori . Helicobacter Pylori is a bacterium normally present inside the stomach (it bears very well the acid environment) and has no significant health consequences.
However, if the human body's immune defenses lose their effectiveness, the bacterium in question is free to proliferate uncontrollably and colonize its host, causing an infection.
Scientific studies have shown that people with an Helicobacter Pylori infection are 3-6 times more at risk of developing gastric cancer than people who are not infected, ie healthy.
Most likely, such an increase in the risk of getting gastric neoplasia would depend on the inflammation of the mucous membrane of the stomach, triggered by Helicobacter Pylori . In the characteristics, this inflammation is very similar to the inflammation present at the aforementioned autoimmune atrophic gastritis: in fact, it is chronic and causes the loss of gastric glands, in favor of fibrous tissue and glands typically resident in the intestine.
- Cigarette smoke . It is among the main risk factors of many cancers, not only of stomach cancer.
According to Anglo-Saxon statistics, one case per 5 of gastric cancer would relate to a smoker and would be linked, in some way, to smoking.
According to what the experts say, the risk of developing a neoplasm of the stomach would go up from 40%, for a medium level smoker, to more than 80%, for a heavy smoker. From these numerical data it is possible to deduce that the more one smokes and the greater the probability of developing the neoplasm in question.
- Alcohol abuse . Alcoholic substances irritate the mucous membrane of the stomach, affecting the secretion of protective mucus. The constant mucus deficiency predisposes to chronic gastritis, which, in turn, predisposes to tumors at the level of the stomach.
- Advanced age . Generally, the accumulation of mutations that cause tumors like the stomach is a slow process, which takes many years. This explains why people with a gastric neoplasm are more often elderly people.
- Belonging to the black, Hispanic or Asian race . Compared to the Caucasian race, these breeds are definitely more at risk of stomach cancer.
- Obesity and overweight . The predisposing power of obesity and overweight is uncertain: according to some experts, being overweight or obese would be a risk factor; according to others, however, it would not be so.
To clarify these uncertainties, further studies and observations are needed.
Other risk factors for stomach cancer
Among the less common risk factors of stomach cancer, it is worth mentioning: Barrett 's esophagus, Ménétrier's syndrome, diabetes, having undergone a partial stomach removal operation ( partial gastrectomy ) and exposure to particular harmful chemical substances (eg: those working in the rubber production industries).
Epidemiology
Worldwide, stomach cancer is the fifth most common form of malignant neoplasm and the third most common cause of cancer death after lung cancer and liver cancer. It should be pointed out, however, that its annual incidence varies considerably according to the geographic area considered: in fact, where there is less control of risk factors (eg: in Japan, where salted foods are usually consumed, or in the countries of Africa, where an enormous diffusion of Helicobacter Pylori remains, the number of new cases per year of gastric cancer is decidedly higher, compared to the nations that have "learned" to control the predisposing conditions (ex: United States, United Kingdom, Italy etc. that prefer frozen food storage, have excellent availability of antibiotics against Helicobacter Pylori etc.).
Stomach cancer is a neoplasm whose spread in the population increases with age: statistics in the hand, in fact, up to 40-45 years is rare, but from this age onwards it begins to become more and more frequent, reaching the peak frequency around 69-70 years.
It is men who suffer most from stomach cancer : in fact, the ratio between sick males and sick females is 1.6: 1 (in practice, for every 16 sick men there are 10 sick women).
Gastric cancer has always predominantly affected people in the lower social classes ; this is explained by the limited economic possibilities of the poorest people, which prevent them from providing a healthy, quality and preventive diet against stomach cancer and in general all the pathologies of the digestive system.
Some interesting numbers of stomach cancer:
- For 2017, in the United States (where just over 321 million people reside), statistical experts predict around 28, 000 new stomach cancer diagnoses (17, 750 men and 10, 250 females) and approximately 10, 960 deaths due to same type of tumor;
- The peak incidence of gastric cancer is around 70 years;
- 6 out of 10 people whose doctors diagnose stomach cancer are aged 65 and over;
- In the United States, gastric cancer was the leading cause of death from cancer until 1930. Today, in this "special" ranking, it occupies a decidedly lower position: it has, in fact, fallen to 14th place;
- In 2012, at a global level, there were 952, 000 diagnoses of stomach cancer (the fifth most common form of cancer);
- In Japan, stomach cancer is the most common form of cancer in both men (75 cases per 100, 000 male individuals) and women (35 cases per 100, 000 female individuals);
- In Europe, the number of new cases of stomach cancer is around 190, 000 each year;
- In the UK, stomach cancer is the 15th most common form of cancer and the tenth most common cause of cancer death;
- In Italy, every year there are just over 8, 000 new cases of gastric cancer, in the male population, and around 5, 500 new cases of stomach cancer, in the female population;
- The survival rate at 5 years from the diagnosis of gastric cancer at the beginning is 67%; the 5-year survival rate from the diagnosis of a gastric neoplasm spread to neighboring organs and lymph nodes is 31%; finally, the 5-year survival rate from the diagnosis of a stomach tumor that has disseminated metastasis is 5%.
