Stomach cancer: what should a primary care physician pay attention to?
NewsTumors of the digestive system occupy leading positions in the structure of cancer incidence in Russia and the world. Is it possible to prevent their development and what is the role of the primary care physician in this?
Dmitry Bordin, Head of the Department of Pathology of the pancreas, biliary tract and Upper digestive tract of the MCSC named after A.S. Loginov, MD, answered these and other questions in an interview with the medical scientific and practical portal "Attending Physician".
WHAT IS THE DYNAMICS AND STATISTICS OF MALIGNANT NEOPLASMS IN RUSSIA – WHAT HAS CHANGED OVER THE PAST 10 YEARS?
In recent years, there has been a downward trend in the incidence of certain types of cancer, but the "five" most common oncological diseases remain relatively stable. According to 2020 statistics, lung cancer ranks first in men in terms of incidence, prostate cancer ranks second, colorectal cancer ranks third, stomach cancer ranks fourth, and kidney cancer ranks fifth. Consequently, gastric cancer ranks fourth in the structure of oncological morbidity, while the third in the structure of oncological mortality. That is, with this type of cancer, a fairly significant part of patients die quickly enough, unlike colorectal cancer, in which the incidence is higher, but the mortality rate is much lower, since it responds better to treatment, although it occurs more often. In women, colorectal cancer ranks second after breast cancer in the structure of cancer incidence; gastric cancer ranks seventh and fourth in the structure of cancer incidence and mortality, respectively. The one-year mortality rate for malignant neoplasms of the stomach exceeds 40%, which is primarily due to late diagnosis. When a common cancer with distant metastases is detected, the survival rate is only 5%.
Speaking about other types of cancer of the digestive system, for example, pancreatic cancer, it should be noted that in recent years there has been a marked increase in the incidence. In terms of prognosis, pancreatic cancer is one of the most unfavorable due to its aggressive course and rapid progression. The prevalence of esophageal cancer is also increasing, which is associated with an increase in the prevalence of gastroesophageal reflux disease (GERD). The latter, in turn, is due to an increase in the number of obese people. While esophageal squamous cell carcinoma in most cases is associated with nutritional characteristics, in particular, frequent consumption of hot drinks (which is typical for the population of some Asian countries), esophageal adenocarcinoma is a consequence of the long course of GERD.
Thus, cancer alertness in relation to tumors of the digestive system is an extremely important issue, especially in Russia, where the incidence of these types of malignant neoplasms remains at a high level.
WHAT FACTORS CONTRIBUTE TO THE DEVELOPMENT OF COLORECTAL CANCER AND GASTRIC CANCER AND WHAT DIAGNOSTIC METHODS ARE AVAILABLE TO PATIENTS TODAY?
Colorectal cancer, as a rule, is a consequence of chronic inflammatory processes and the formation of polyps, so early detection and elimination of these changes is not difficult – it is recommended to perform a colonoscopy after 50 years and remove polyps when they are detected. If no formations are found, the next colonoscopy is performed after 5 years; if pathology is detected, then the further mode of colonoscopy is determined by the nature of the find. Patients with colon or rectal cancer in the family history are a high-risk group and their first colonoscopy should be performed 10 years before the age at which a blood relative was diagnosed with cancer.
In Moscow, colonoscopy and gastroscopy under sedation are available to patients under compulsory medical insurance at Botkin Hospital and V.M. Buyanov State Clinical Hospital. In 2022, two more endoscopic centers with such capabilities will open – in GKB No. 40 in Kommunarka and in the new building of the Moscow Clinical Research Center named after A.S. Loginov.
If the patient is still not ready for a colonoscopy or does not have the opportunity to undergo an examination, you can assign an "intermediate" study to form a risk group – a stool test for hidden blood, which is available as part of a medical examination. The test is highly sensitive because it detects only human hemoglobin. It is necessary to conduct at least three tests, and at least one positive result will be an indication for a colonoscopy. Nevertheless, colonoscopy remains the preferred method of diagnosing colorectal cancer, especially if it has a family history.
As for stomach cancer, there is an epidemiological trend towards a decrease in incidence. This is due to a decrease in the prevalence of helicobacter pylori infection, which causes at least 90% of cancer cases; in the structure of inflammatory diseases of the gastric mucosa, including gastritis, Helicobacter pylori (H. pylori), is the dominant pathogenetic factor and was recognized as a class I carcinogen back in 1994. The role of the Epstein-Barr virus is discussed.
H. pylori infection usually occurs in childhood. Infection in all cases causes an inflammatory process, and for a long time it can be asymptomatic. In the early stages of infection, chronic active gastritis develops, then after decades it can transform into atrophic, in which the number of normal cells decreases; then intestinal-type cells appear (intestinal metaplasia), followed by intestinal dysplasia and malignant degeneration of these cells. This course of helicobacter infection opens up a number of possibilities. Since helicobacter infection causes the majority of cases of gastric cancer, primary prevention is possible, that is, the detection and timely treatment of infection. For primary prevention, patients aged 20-30 years are tested for H. pylori and, if detected, treatment is prescribed. Effective eradication therapy can also cure gastritis and reduce the risk of peptic ulcer disease, as well as damage to the stomach when taking nonsteroidal anti-inflammatory drugs or oral anticoagulants, reducing the risk of bleeding. Secondary prophylaxis includes endoscopic examination – detection of precancerous changes (atrophic gastritis, intestinal metaplasia). Properly performed endoscopy allows you to detect cancer at an early stage and even cure it with the help of endoscopic techniques – it is enough to remove the pathological area of the mucous membrane.
Despite the fact that helicobacter infection leads to cancer in 1-2% of infected people, probably in the presence of additional risk factors (nutritional characteristics, environment) and genetic predisposition, it always requires treatment, because we cannot be sure that it will not lead to a malignant process in a particular patient.
ARE THE POSSIBILITIES OF "STANDARD" GASTROSCOPY SUFFICIENT TO DETECT PRECANCEROUS CHANGES? HOW EFFECTIVE IS ROUTINE GASTROSCOPY?
Endoscopy is an operator-dependent technology, which also depends on the quality of the technique and the conditions of the procedure, the collection of morphological material. It is important that the doctor has sufficient experience and onco-alertness and has high-quality equipment (for example, narrow-spectrum endoscopy). In addition, it is important that the examination lasts at least 7 minutes (in some cases, it may take up to 20 minutes of examination to detect small changes). It is clear that if the study is carried out with a conventional endoscope and without sedation, the probability of detecting small initial changes is quite small. To solve the problem of diagnosing cancer in the early stages, it is necessary to conduct a fairly thorough examination, preferably under sedation. If atrophy of the mucous membrane is suspected, the endoscopist should take a biopsy from 5 points, according to the results of a morphological examination using the OLGA system, the degree and stage of gastritis are determined. When gastritis is detected at stages 3 and 4, even after successful eradication of H. pylori, there is a high risk of gastric cancer, therefore the patient needs dynamic endoscopic observation according to the recommendations of MAPS II. Thus, gastroscopy must meet the basic conditions – a good endoscopist, technique and sedation.
With endoscopic screening in South Korea, gastric cancer at stage 1 is detected in 80% of cases, due to this, the risk of death from stomach cancer is reduced by almost 50%, while the effect depended on the number of studies: a single endoscopic examination reduced the risk of death by 40%, a double one – by 68%, more than three times – by 81%. In Russia, gastric cancer at stage 1 is detected in 13%, in Moscow in 21% of cases. We have something to strive for. Taking into account the fact that, according to large meta-analyses, H. pylori eradication reduces the risk of developing stomach cancer by the same 50%, timely diagnosis and treatment of helicobacter infection remain the most cost-effective and affordable method of preventing stomach cancer. Of course, ideally, primary and secondary prevention of stomach cancer should be combined.
Speaking of colorectal cancer, the so-called adenoma detection rate is used as a quality control measure of the examination – the number of polyps detected by the endoscopist for a certain number of studies. Endoscopists, especially young specialists, use this indicator as an internal quality control system.
ARE MOSCOW CLINICS EQUIPPED WITH SUCH "PROGRESSIVE" TECHNOLOGIES?
Although Moscow is at the forefront of endoscopy, the number of public medical institutions where it is possible to conduct a high-quality examination using high-tech equipment is limited. The situation should be changed by the opening of endoscopic cents.
WHAT IS THE PLACE OF RUSSIAN SCIENCE IN THE DEVELOPMENT OF METHODS FOR THE DIAGNOSIS AND TREATMENT OF ONCOLOGICAL DISEASES: ARE THERE ANY STUDIES THAT ARE BEING CONDUCTED OR INITIATED IN OUR COUNTRY?
There is no national science. Any science is international, and it develops through the exchange of knowledge and competition. The main thing is that doctors should be interested in conducting qualitative research and implementing the results. Unfortunately, there is no organized colorectal cancer screening program in our country yet, but the professional community understands that this needs to be done, because if the disease is detected at an early stage, the survival rate exceeds 90%.
International experience demonstrates success in reducing the incidence and mortality of stomach cancer as a result of treatment of helicobacter infection. Recently published data on the effectiveness of the H. pylori mass eradication program in Taiwan. The period from 2004 to 2018 is analyzed. As a result of this program, which covered more than 90% of the population, it was possible to significantly reduce both the prevalence of infection from 64% to 15%, the prevalence of peptic ulcer disease from 17% to 3%, and the incidence of stomach cancer and mortality from stomach cancer by 53% and 25%, respectively, and the risk of re–infection did not exceed 1% per year.
We participated in an international observational study of real clinical practice "H. pylori infection Registry "Hp-EuReg"". Since 2013, more than 50 thousand patients from most European countries have been included in the register, about 9 thousand of them from Russia. As a result, we have invaluable data on the correctness of the use of diagnostic methods and the effectiveness of the therapy regimens used. Based on the materials of the register, articles have been published in leading journals of the world, co-authored by our scientists from different regions of Russia. Error analysis allowed to develop measures to improve the knowledge of doctors and improve the results of treatment. In addition, these data were taken into account in the preparation of new international recommendations for the diagnosis and treatment of H. pylori infection "Maastricht VI", which will be published this year.
WHAT IS THE REASON FOR THE HIGH INCIDENCE OF ADVANCED FORMS OF STOMACH CANCER? LOW ONCOLOGICAL ALERTNESS OF DOCTORS, PASSIVITY OR FEAR OF PATIENTS? PROBLEMS OF THE MHI SYSTEM?
Secondary prevention, i.e. the detection of precancerous changes and early cancer, is the cooperation of the doctor and the patient. At the same time, it is important to have a screening system, it has begun to take shape in Moscow. Primary prevention is easier. Stomach cancer is one of the few oncological diseases, the avoidable cause of which is known. The best, most cost-effective strategy is to identify and eliminate H. pylori in a timely manner. However, there is a huge problem here – this is the thinking of a number of representatives of the medical community who consider the presence of H. pylori to be the norm. In one of our studies, H. pylori was detected among medical professionals in half of the cases, but only 70% agreed to undergo treatment. That is, some doctors underestimate the risks not only for their patients, but also for themselves personally. In addition, not all doctors follow the recommendations for choosing therapy regimens, and also prescribe them for 7 or 10 days, although, according to Clinical Guidelines, the duration of therapy should be 14 days. 30 days after the completion of treatment, a control test is required to show whether the infection has been cured. Such a recommendation is often ignored.
Another organizational problem is the availability of highly sensitive tests for the diagnosis of helicobacter infection. The 13C-urease breath test has the greatest diagnostic value. It does not require an EGDS. The patient exhales a sample of air into a special bag on an empty stomach. Then it takes a solution of urea labeled with a non-radioactive isotope of carbon 13C; in the presence of H. pylori in the stomach, the urease produced by the bacterium breaks down the 13C urea entering the stomach to form carbon dioxide, the carbon of which carries the label. Therefore, in the second portion of exhaled air, after 30 minutes, the concentration of 13C increases in an infected H. pylori. The analyzer fixes this increase and gives a conclusion. The sensitivity of the test exceeds 90%. This test can be done in network laboratories, but it is not paid for by the compulsory medical insurance. The rapid urease test available under the OMS is less sensitive (about 75%), which means that a negative result cannot be a reason for excluding H. pylori. Patients go to additional studies less often, including due to financial considerations. Thus, it is not enough just to train doctors – it is necessary to give them a reliable diagnostic tool in their hands.
ARE CHILDREN WHOSE PARENTS HAD A HELICOBACTER INFECTION AT AN INCREASED RISK OF INFECTION?
Children, as a rule, become infected from their parents. If you have a family history of peptic ulcer disease or stomach cancer, then these people are also at high risk. However, it is important to emphasize that the tactics of treating helicobacter pylori infection for adults and children are radically different: in adults, the presence of H. pylori is the basis for the appointment of eradication therapy, while in children it is necessary to identify and treat infection only if there are absolute indications, erosive and ulcerative lesions of the stomach and duodenum. The intestinal microflora in children is extremely sensitive to the action of antibiotics, so eradication should be carried out only in situations where the benefits outweigh the risks. In addition, children have a high risk of re-infection.
CAN A HELICOBACTER INFECTION BE CURED WITH PROBIOTIC DRUGS?
H. pylori is very well adapted to the gastric mucosa, so a 14-day regimen of therapy with a proton pump inhibitor with two or three antibiotics remains the basis of treatment. At the same time, undesirable phenomena often occur, the severity of which decreases with the use of certain strains of probiotics, which contributes to taking a full course of therapy and increasing its effectiveness.
Of course, alternative eradication schemes without antibiotics are being investigated. Recently, we completed a pilot study of gastrokur dietary supplements (active ingredients –dihydroquercetin and indole-3-carbinol) in combination with pantoprazole in patients with helicobacter infection without erosive and ulcerative lesions and severe symptoms. Out of 10 patients, 2 had complete eradication. For a drug of plant origin, 20% is a good result, because it means that every fifth patient will be able to recover without antibiotics. Such methods are promising as an alternative approach to eradication. They can be recommended to patients as primary treatment, and in case of ineffectiveness, antibiotic therapy can be prescribed.
