Stomach cancer: signs and symptoms, causes, treatment, prognosis

What is stomach cancer?

Stomach cancer Is a general term for cancer affecting the stomach. Typically, it is a malignant tumor that arises from the cells lining the stomach. These cells, like all cancer cells, show abnormal and rapid growth. At the onset of the disease, symptoms are usually absent. As the disease progresses, symptoms such as indigestion, nausea, vomiting, and early satiety (early satiety) may develop. The cause of stomach cancer is multifactorial, which means that several factors are necessary for the development of cancer, which come together. These factors can include genetic, immunological, infectious and environmental factors. Stomach cancer usually develops randomly for unknown reasons (sporadically) and usually has no family history.

There are several different forms of stomach cancer. The most common of these is adenocarcinoma, which accounts for about 90-95% of patients with stomach cancer. Other types include primary gastric lymphoma, gastrointestinal stromal tumor (GIST), and neuroendocrine (carcinoid) tumors of the stomach. Rarely, other forms of cancer can develop in the stomach, including squamous cell carcinoma, small cell carcinoma, and leiomyosarcoma. Malignant neoplasms in other organs rarely metastasize to the stomach, although breast cancer is a malignant neoplasm that in very rare cases can spread to the stomach. This article focuses primarily on gastric adenocarcinoma.

The stomach is the organ in which most of the digestion takes place. The stomach is connected to the esophagus (a tube connected to the throat) at the gastroesophageal junction. After food is chewed and swallowed, it travels up the throat, through the esophagus and into the stomach. The lower part of the stomach is connected to the small intestine called duodenum. Stomach cancer (adenocarcinoma) can occur anywhere in the stomach, but is most often caused by the cells that make up the lining of the stomach (the cells that produce mucus). When cancer forms near the esophagus, it can be called gastroesophageal junction cancer.

Signs and symptoms

Signs and symptoms can vary greatly from one person to the next. Specific signs depend on many factors, including the exact location of the tumor, the extent to which the tumor has spread to nearby tissues or organs, the specific organs involved and whether the disease has remained localized or has spread to other areas of the body (metastasized). Stomach cancer is a slow-growing cancer that usually develops over a year or longer.

There are usually no symptoms in the early stages. As the disease progresses, a variety of symptoms can develop. These symptoms include indigestion (dyspepsia), which may be severe and persistent, nausea, vomiting, feeling full after eating small amounts of food (early satiety), feeling bloating after eating and heavy persistent heartburn. Sometimes there may be discomfort or pain in the stomach, difficulty swallowing (dysphagia), fatigue and unintentional weight loss. The pain is mild and indistinct in the early stages of the disease, but becomes more severe and constant as the disease progresses.

Loss of blood from the stomach may occur, which may go unnoticed, leading to anemia (low level of circulating red blood cells). Anemia can lead to fatigue, pale skin and shortness of breath. Although this is rare, in advanced cases, patients may vomit blood (hematemesis) or dark sticky stools (melena) due to blood in stool.

Sometimes the first signs or symptoms of stomach cancer appear after the tumor has spread to other parts of the body. The exact symptoms will depend on where the cancer has spread, but common symptoms include an inability to tolerate any oral food intake due to intestinal obstruction, fractures, neurological changes, and bloating due to fluid buildup (abdominal ascites).

Some other signs of advanced disease include the formation of a mass in the upper center of the abdomen or an enlarged liver (hepatomegaly).

Causes and risk factors

The exact underlying cause of stomach cancer is not fully understood. The cause of cancer is a complex issue, and researchers suggest that multiple factors are involved in the development of stomach cancer. These factors can include genetic, environmental, infectious and immunological factors.

Most patients develop stomach cancer incidentally without a family history (sporadically). Cancer is often associated with different genes that are associated with the development of cancer. When a change (DNA mutation) occurs in a gene associated with cancer, the protein product created by that gene may be defective, ineffective, absent or overproduced. Variations in genes associated with cancer have been shown to increase a person's risk of developing cancer (genetic predisposition). Genetic predisposition means that a person has a gene or genes for a disease, but the disease is not will develop if no additional genetic or environmental factors are also present Wednesday. These variations are somatic mutations and can occur in any cell of the body other than germ cells (ovum or sperm). Consequently, these variations are not inherited and are acquired throughout life. Understanding the genetic factors that underlie stomach cancer is essential and may lead to more targeted treatments in the future.

In rare cases, stomach cancer can be inherited. A risk factor for this disease is the presence of stomach cancer in a first-degree relative. Some of these families may have a mutation associated with known risk factors that affects multiple family members. For example, there might be clustering of an infection H. pylori within families or there may be a predisposition to chronic inflammation of the gastric mucosa (chronic atrophic gastritis).

There are hereditary cancer syndromes (genetic disorders) that increase the risk of stomach cancer (and often other cancers). Approximately 1-3% of patients with stomach cancer have a hereditary cancer predisposition syndrome. These are inherited diseases in which a person has a higher risk of developing cancer than the general population. These syndromes include hereditary diffuse gastric cancer (mutations CDH1), gastric adenocarcinoma and proximal gastric polyposis, familial gastric intestinal cancer, hereditary breast and ovarian cancer syndrome (due to mutations BRCA1 or BRCA2 gene), lynch syndrome, which is also called hereditary non-polyposis colorectal cancer; familial adenomatous polyposis; Li-Fraumeni syndrome and Peutz-Jeghers syndrome.

Several different environmental factors have been linked to stomach cancer. Infection Helicobacter pylori (H. pylori) is strongly associated with stomach cancer, especially cancer of the lower stomach. H. pylori - a type of bacterial infection that occurs in the mucous layer of tissue lining the stomach. This infection can cause inflammation and ulcers in the stomach. Long-term or chronic infection H. pylori associated with severe inflammation and precancerous changes in the cells of the gastric mucosa. Most people who are infected H. pylori, cancer never develops.

Individuals who have a rare cancer called mucosal lymphoid lymphoma are at a greater risk of developing gastric adenocarcinoma than the general population. Patients with certain medical conditions, including pernicious anemia, combined variable immunodeficiency, or Menetrie's disease (hypertrophic gastropathy) are also at increased risk of stomach cancer. Small benign growths (polyps) are usually found in the stomach. Many people have these polyps. A certain type of polyp, called an adenoma, can change and become cancerous.

People who have had previous stomach surgery, such as an ulcer, are also at increased risk. Some research suggests that a person's diet may affect the risk of stomach cancer and that a diet high in salt and foods that are smoked or pickled in salt, including certain meats or salted fish, may increase the risk of cancer stomach. There are studies showing that a diet high in fried foods, processed meats, and fish can increase the risk of stomach cancer. There are also studies that have shown that eating fruits and vegetables can help prevent stomach cancer.

People who smoke have a doubling of the risk of stomach cancer. Smoking especially increases the risk of cancer near the esophagus. There is also an increased risk for people who work in certain industries where they are exposed exposure to toxic materials, including the coal, metallurgical, rubber industry (professional impact). Although the reason for this is unknown, people with Type A blood also have a slightly increased risk of stomach cancer. Other potential factors have been suggested, including obesity, alcohol consumption and infection Epstein-Barr virusbut the evidence is inconsistent and such links remain unproven.

Cancer of the gastroesophageal junction may be associated with gastroesophageal reflux (GERD). GERD is a condition in which stomach contents flow back into the lower esophagus.

Affected populations

Globally, stomach cancer is the fifth most common cancer and the third leading cause of cancer death, accounting for 7% of cases and 9% of deaths. According to statistics, only 29% of patients recover. More often stomach cancer occurs in men.

In Russia, stomach cancer consistently ranks second in the structure of oncological diseases (15.8% in men and 12.4% in women), the disease is widespread in Korea, Japan, the United Kingdom, South America and Iceland. In Korea, stomach cancer ranks first in the structure of cancer incidence (20.8%) and second in mortality.

Metastases occur in 80-90% of patients with gastric cancer, the six-month survival rate is 65% in the case of early diagnosis of the disease and less than 15% in the later stages of the process. On average, the highest survival rate for stomach cancer is noted in Japan - 53%, in other countries it does not exceed 15-20%.

In one case out of fifty, gastric cancer is diagnosed in patients complaining of dyspepsia.

Symptomatic disorders

Symptoms of the following conditions may be similar to those of stomach cancer. Comparisons can be useful for differential diagnosis.

There are many conditions that can cause symptoms similar to those seen in stomach cancer. These conditions include forms of inflammation, irritation, or erosion of the stomach lining (gastritis), including acute gastritis, atrophic gastritis and chronic gastritis. Esophageal cancer, narrowing (stricture) of the esophagus, and inflammation of the esophagus (esophagitis), stomach ulcer, viral gastroenteritis and bacterial gastroenteritis can also cause similar symptoms.

• Gastrointestinal stromal tumor (GIST) belong to a group of cancers known as sarcomas of soft tissues. Tumors usually arise from the intestinal tract, most often in the stomach, then in the small intestine, and then in the colon / rectum, and rarely in the esophagus. There are also tumors that develop in the membranous tissue lining the stomach wall (peritoneum) or in the fold of such membranous tissue (omentum). There are also reports of cases of tumors arising in appendix and / or pancreas. These tumors most often present with abdominal pain, bleeding, or signs of intestinal obstruction. Most often, they spread to the abdominal organs and into liver, although there are rare cases of spread to the lungs and bones. Some GISTs are not malignant (benign) and are not distributed; others are aggressive with extensive local invasion as well as distant metastases. Most cases are the result of a change (mutation) in one of two genes, KIT or PDGFR, which leads to continued growth and division of tumor cells. There are several reported cases of families in which the gene mutation is inherited; however, most tumors occur randomly for no apparent reason (sporadically) and are not inherited (acquired mutation). Most cases occur in older people.
• Primary gastric lymphoma Is a general term for a type of cancer that occurs in the stomach. Approximately 90 percent of patients with primary gastric lymphoma are either gastric lymphoma associated with mucosal lymphoid tissue or diffuse large B-cell lymphoma of the stomach. Gastric lymphoma associated with lymphoid tissue of the mucous membrane often results from infection with bacteria Helicobacter pylori. There is considerable disagreement in the medical literature regarding the precise definition, classification, and stage of primary gastric lymphoma.

Diagnostics

The diagnosis of stomach cancer is based on the identification of characteristic symptoms, a detailed history of the patient and his family, a thorough clinical examination, and various specialized tests. Because stomach cancer usually does not cause symptoms in the early stages of the disease, it is often not diagnosed until the disease progresses.

- Analyzes and examination.

Complete blood count is a standard blood test. This test may be ordered if stomach or gastrointestinal cancer is suspected for detecting low levels of circulating red blood cells (anemia) that may result from loss of blood. Another test that can be ordered is a fecal occult blood test. During the analysis, the stool is checked for the presence of blood that is not visible to the naked eye.

Doctors may order an upper endoscopic examination in individuals with suspected gastric cancer. This exam allows doctors to look at the upper part of the digestive tract, including the esophagus, stomach, and duodenum. During this examination, doctors insert a thin, flexible tube into the person's throat. Attached to this tube is a tiny camera that allows doctors to visually examine these areas. If abnormal growth or abnormal tissue is seen, doctors may pass instruments through the tube to allow them to take a tissue sample.

All tissue samples taken are then examined under a microscope. Surgical removal and microscopic examination of a tissue sample is called a biopsy. This biopsy sample is then examined by a pathologist, who is a specialist trained to examine tissues and cells to find the disease and determine which disease is present.

Doctors may also prescribe modern imaging (X-rays), especially computed tomography and endoscopic ultrasound. During computed tomography, a computer and X-rays are used to create a film showing cross-sectional images of specific tissue structures. Doctors will examine the chest and abdomen to determine if stomach cancer has spread (metastasized) to these sites.

Endoscopic ultrasound is performed to determine the depth and exact location of the tumor and determining if the cancer has spread to the stomach wall or has affected any of the nearby lymph nodes. Ultrasound uses high-frequency radio waves to create images of specific structures, such as internal organs. Radio waves are reflected from internal structures of the body (echo), and the echo is recorded to create an image (sonogram).

Sometimes a double contrast study of the gastrointestinal tract may be recommended. The examination uses X-rays and barium. Barium is a chalky white metallic element. The affected person swallows a solution containing barium that covers the esophagus, stomach, and small intestine. X-rays cannot pass through barium, so X-rays will be able to delineate structures or tissues in these areas. This will help doctors determine the presence and extent of the disease.

In some cases, doctors may recommend laparoscopy or laparotomy to obtain biopsy samples and determine the stage of the cancer. The laparoscopy procedure consists of examining the abdominal cavity using a light tube (laparoscope) inserted through incisions in the abdominal wall. Laparotomy is a surgical procedure in which the abdominal cavity is opened, the organs are carefully are examined for signs of disease, and tissue samples are taken for examination under microscope. Sometimes liquid samples are taken and examined. This can include fluid from the abdomen for ascites.

- Staging.

When a person is diagnosed with stomach cancer, an assessment is also required to determine the extent or "stage" of the disease. The stage is important for characterizing the potential course of the disease and determining the appropriate treatment approaches. Various diagnostic tests (eg, blood tests, computed tomography) can be used to determine the stage of stomach cancer. Stomach cancer can be staged by the American Joint Cancer Committee (AJCC) / Alliance International Cancer Control (UICC), which is based on a classification system for tumors, nodes and metastases (TNM).

Standard treatments

The therapeutic management of people with stomach cancer may require the coordinated efforts of a team of medical professionals, such as physicians, specializing in the diagnosis and treatment of diseases of the digestive system (gastroenterologists), doctors specializing in the diagnosis and treatment cancer (medical oncologists), doctors who specialize in the diagnosis and treatment of cancer through surgery (oncologists), doctors who specialize in the use of radiation therapy to treat cancer (radiation oncologists), oncology nurses, psychiatrists, nutritionists and other specialists in health care. Psychosocial support is also important for the entire family.

Specific therapeutic procedures and interventions can vary depending on many factors, such as the stage of the disease; the size of the tumor; a specific subtype of stomach cancer; Whether the tumor has spread the presence or absence of certain symptoms; age and general health of a person; and / or other elements. Decisions regarding the use of specific drug regimens and / or other treatments must be made doctors and other members of the medical team after careful consultation with the patient, based on the specifics of his case; a thorough discussion of the potential benefits and risks, including possible side and long-term effects; patient preferences; and other relevant factors.

Surgery - The main treatment option for stomach cancer. The exact operation and the extent of the operation depend on the type and stage of the tumor. Surgery may include endoscopic resection, in which the cancer has not spread to nearby lymph nodes. Surgeons pass a thin, flexible tube up the throat to the stomach. They can guide instruments through a tube, which allows them to surgically remove the tumor and any diseased tissue in the stomach wall. Gastric cancer is rarely small enough to allow endoscopic resection. In addition, this method depends on the experience of the physician performing the procedure.

For most patients with cancer confined to the stomach and adjacent lymph nodes, surgeons must remove part of the stomach along with the tumor. This is called subtotal (partial) gastrectomy. If the cancer is in the upper part of the stomach, it may sometimes be necessary to remove part of the esophagus. If the cancer is in the lower part of the stomach, removal of the duodenum may sometimes be necessary.

Sometimes surgeons have to remove the entire stomach and some of the surrounding tissue. This is called a total gastrectomy. It is most often recommended when the cancer has spread to the stomach. During this operation, the end of the esophagus is connected directly to the duodenum to allow the passage of food.

A common part of surgery to remove part or all of the stomach is to remove nearby lymph nodes. This part of the operation may be called lymphadenopathy.

Sometimes chemotherapy or radiation therapy can be performed before or after surgery. This is called neoadjuvant or adjuvant therapy. When used in conjunction with surgery, chemotherapy may be prescribed before surgery (neoadjuvant) for shrinking the tumor or after surgery (adjuvant therapy) to remove any remaining cancer cells and reduce the risk relapse. Sometimes chemotherapy can be prescribed before and after surgery (in the perioperative period). Various drug combinations can be used; this is called a chemotherapy regimen. When chemotherapy is given, the specific chemotherapy regimen may vary. Different medical centers may have different preferences regarding the best approach to treatment and which chemotherapy regimen is best for each person.

5-FU / leucovorin and oxaliplatin are often used as first treatments for stomach cancer that has spread locally or has spread to other parts of the body. Docetaxel (Taxotere) is approved for the treatment of gastric adenocarcinoma or gastroesophageal junction that occurs in people who have not received chemotherapy for advanced disease.

Radiation therapy can also be used as an adjuvant therapy. Radiation therapy is a method of using high doses of radiation to kill cancer cells and shrink tumors. Radiation therapy predominantly destroys or damages rapidly dividing cells, especially cancer cells. The radiation travels through the affected tissue, destroying cancer cells, minimizing exposure and damage to normal cells. Radiation therapy destroys cancer cells by releasing energy that damages the genetic material of the cells, preventing or slowing their growth and replication. Radiation therapy is sometimes given at the same time as chemotherapy (chemoradiotherapy). For example, in the treatment of gastroesophageal junction cancer, chemoradiotherapy is often given after surgery.

Treating an infection H. pylori using antibacterial drugs is also important.

- DIRECTED THERAPY.

Targeted therapy targets a specific molecule, protein or substance to block growth and spreading cancer rather than killing cancer cells (cytotoxic treatments) such as chemotherapy or radiation therapy. Targeted therapy is less likely to damage healthy cells. There are several FDA-approved targeted treatments for stomach cancer.

In 2017, the FDA granted expedited approval of pembrolizumab (Keytruda) for the treatment of stomach cancer or gastroesophageal junction that recurs and locally progresses or spreads (metastasizes). Pembrolizumab is approved for patients whose cancer has the PD-1 protein and has worsened despite two or more other treatments. Pembrolizumab is a new type of therapy called immunotherapy. This type of treatment aims to enhance the body's innate ability to fight cancer cells using the immune system. For example, the most common form of immunotherapy called PD-1 or PD-L1 blockade relieves Immune system brakes, which are used by some cancers to evade immune cells.

In 2015, the FDA approved ramucirumab (Tsiramza) for the treatment of advanced stomach or gastroesophageal junction cancer that cannot be treated with other treatments. In 2010, the FDA approved trastuzumab (Herceptin) along with chemotherapy to treat stomach cancer or gastroesophageal cancer (adenocarcinoma) that produces too much HER2 protein and spreads (metastasizes).

Forecast

If cancer is diagnosed and treated before it has spread outside the stomach, the 5-year survival rate is 69%. If the cancer has spread to surrounding tissues or organs and / or regional lymph nodes, the 5-year survival rate is 31%. If the cancer has spread to a distant part of the body, the 5-year survival rate is 5%.

It is important to remember that survival statistics for people with stomach cancer are approximate. The estimate is based on annual data based on the number of people with this cancer in the United States. Also, every 5 years, experts measure survival statistics. Thus, the score may not reflect the results of a more accurate diagnosis or treatment available in less than 5 years. If you have any questions about this information, talk to your doctor.