There are no laboratory tests specific to early gastric cancer. However, laboratory data may undergo changes in advanced gastric cancer. The most common finding is iron deficiency microcytic hypochromic anemia. Even with early cancer, 20% of patients have a decrease in hemoglobin levels. Platelet counts and blood coagulation rates remain within normal limits, with the exception of cases of massive bleeding, disseminated intravascular coagulation, metastatic lesions of the liver, lungs, pancreas, spleen and bone marrow.
Among the biochemical parameters, a slight increase in the level of activity of lactate dehydrogenase and alkaline phosphatase and a decrease in the level of albumin, some fractions of proteins, iron and ferritin in the blood serum can be noted .
A test for occult blood in feces can be negative in about half of patients with advanced gastric cancer. At the same time, a positive benzidine test can be characteristic of patients with pathology in any part of the gastrointestinal tract: peptic ulcers, erosion, gingivitis, reflux esophagitis, hemorrhagic gastritis, hemobilia , colitis, colon polyps, colorectal cancer, hemorrhoidal nodes. An analysis of feces for occult blood can give a false positive result, especially if the patient on the eve ate steaks with blood, turnips, broccoli and radishes. In people older than 40 years, a positive result is an indication for the study of the colon ( colonoscopy or sigmoidoscopy + irrigoscopy with double contrast). The level of tumor markers does not increase with early gastric cancer. The most common gastric cancer cases are CA19-9, CA50, CA72-4, CA546, and CEA. Highly and moderately differentiated tumors are characterized by an increase in the level of at least 2-3 markers, while in patients with low- and undifferentiated tumors of the stomach, the level of markers does not increase. Multivariate analysis suggests that tumor markers are independent prognostic factors and are second only to T, N, and M.
It is aimed at solving the following two problems: screening to identify patients with non-tumor pathological changes in the mucous membrane and the formation of risk groups; detection of stomach cancer. During endoscopic examination, boundaries, the nature of growth, the shape of the tumor, the absence or presence of spread to the esophagus are fixed. In solving the second problem, the detection of early cancer is of great importance. In some cases, there is a need for chromoendoscopic examination. For this, the gastric mucosa is stained with a 0.1% solution of indigo carmine, which makes it possible to visualize the boundaries of infiltration even with endophytic growth of cancer and synchronous tumors or metastases along the gastric mucosa. For morphological diagnosis, a tumor biopsy is performed to obtain material for histological and cytological studies.
Endoscopic ultrasound of the stomach in many specialized medical centers around the world is included in the register of standard examination methods. Direct contact of the ultrasound probe with the wall of the stomach allows you to get a high degree of resolution when visualizing the layers of the organ wall. This makes endosonography an ideal method for assessing the depth of invasion according to the TNM classification. The criteria for metastatic damage to the lymph nodes are the size of the node more than 5 mm in diameter, rounded shape (a spherical shape is more characteristic for inflammatory nodes) and well-defined contours. Thus, endosonography is an effective and generally accepted method for staging cancer of the stomach. When assessing the depth of invasion (T) and the state of regional lymph nodes (N), the accuracy, sensitivity and specificity of the method, according to different authors, ranges from 80 to 95%.
One of the priority tasks of endosonography in recent years has been the evaluation of the effect of neoadjuvant therapy, since combined treatment is playing an increasingly important role in the treatment of gastric cancer. A study performed prior to the start of treatment does not have predictive significance in relation to the possible effect of chemo – or chemoradiotherapy. The restoration of the structural structure of the stomach wall, established on the basis of endoscopic ultrasound, is obviously a sign of the full effect in the patient after neoadjuvant treatment, however, in some cases, endosonography data is difficult to interpret due to the development of inflammatory and fibrotic changes in the primary tumor or in its place .
An X-ray study using suspensions of barium sulfate as a contrast has two main tasks: screening for gastric cancer and determining the prevalence (depth of invasion and extent) of the malignant process. Most successfully, the first problem was solved in Japan. At the same time, the priority is not the detection of stomach cancer, but the formation of risk groups for subsequent observation. The solution to the second problem is especially relevant before surgery.
The main methods of contrast x-ray examination are tight filling and double contrasting.
In early gastric cancer with an exophytic nature of growth during an X-ray examination, a filling defect is detected. The size of the filling defects varies from 1 to 4 cm in diameter. However, the nature of the surface of a polypoid formation is of greatest importance in the interpretation of data from a contrast study. The contours of a benign hyperplastic polyp are clear, even, while for a malignant tumor, the uneven, serrated contours of the tumor are more characteristic. However, despite the roughness of the contours of early cancer, the surface topography of the polypoid early cancer is similar to that of the surrounding gastric mucosa. Thus, in gastric cancer with invasion of the stomach wall no deeper than the submucosal layer, the tumor surface has the same contours as the surrounding mucous membrane. This symptom is most important in the differentiation of early and widespread gastric cancer. As the tumor grows and the deeper layers of the stomach wall are involved in the tumor process, the similarity between the relief of the mucous membrane and the surface of the tumor is lost, erosion, ulceration ( Borrmann type II ) appear , which is observed in about 26-27% of cases of stomach cancer. Sometimes, despite the increase in the size of the tumor, its ulceration does not occur, this type of tumor is observed in 2-3% of cases (type I according to Borrmann ). Peristalsis at the lesion level is not visible, folds of the mucous membrane break off at the edge of the filling defect.
With early endophytic cancer of the stomach, the x-ray picture is determined by two dimensions, with advanced cancer – three. In other words, with early cancer, the depth of invasion may be omitted, while this parameter is crucial in the more common stages of the disease. The contours of early cancer with an infiltrative nature of growth are clearly traced, but in some cases, when the border between the normal mucous membrane of the stomach and early cancer is blurred, the detection of early cancer presents significant difficulties. Common gastric cancer with an infiltrative nature of growth is most often radiologically represented by a defect in filling or a barium depot, elevated tumor edges and the absence of peristalsis in the affected part of the stomach. In cases of insignificant involvement of their own muscle membrane, widespread gastric cancer radiologically resembles early cancer. This form of common cancer is of type V according to Borrmann . Borrmann type III occurs in 40-45% of cases and is characterized by the presence of a filling defect, a crater with uneven contours in the center of the tumor and the absence of peristalsis around the pathological focus, which is due to the infiltrative growth of cancer. (mucosal clutches break off at the edge of the tumor. Borrmann type IV is found in 21% of cases of widespread gastric cancer. In Western literature, this type is called diffuse infiltrative carcinoma. The x-ray picture of the thickening of the wall of the stomach in a significant area is due to tumor tissue infiltration and the development of fibrotic changes. radiographically stomach deformed , poorly extensible most often affected first antral department. Iposledstvii erosion and ulceration takes considerably the surface of the tumor lesion. Linitis plastica is a kind of type IV advanced cancer Borrmann , is observed most often in the age of 40 years. radiologically characterized by deformation and a decrease in size of the stomach, thickened folds. Identification linitis plasllea in the early stages of tumor development is significant fudnosti and is the only unsolved a problem in diagnosing early stomach cancer.
Computed tomography of the chest and abdominal cavity is also included in the list of studies necessary to evaluate a locally advanced tumor process. CT allows you to establish the size of the primary tumor, enlarged lymph nodes of the retroperitoneal space, metastases in the lung tissue and liver, the presence of lymph nodes affected by metastases along the celiac trunk and its branches. An important condition for proper treatment planning is an accurate assessment of the prevalence of the Process. Despite the fact that CT is part of the algorithm for examining a patient with esophageal cancer, the method is ineffective in determining the depth of invasion of the stomach wall by a tumor.
Ultrasound computed tomography
Ultrasound computed tomography of the organs of the abdominal cavity, retroperitoneal space and cervical-supraclavicular zones allows to detect metastatic lesions of the lymph nodes in the corresponding anatomical areas, as well as distant metastases in the liver and kidneys. P
Ozitron Emission Tomography (PET)
Malignant tumors are characterized by increased glucose metabolism. PET using radioactive labeled fgor-18-deoxyglucose (FDG) allows visualization and quantification of glucose metabolism in tumor tissue. FDH is phosphorylated with the participation of the hexokinase enzyme , converted to FDH-6-phosphate and accumulates in the tissues. By the time of execution of I D) T (60 min after injection), the activity of glucose metabolism in tissues is represented by the concentration of FDH-6-phosphate in the tumor. The use of PET is effective for identifying the primary lesion, affected lymph nodes and distant metastases in cancer of the lung, breast, lymphoma , squamous cell carcinoma of the head and neck, malignant tumors of the musculoskeletal system and colorectal cancer. And only recently have data appeared on the effectiveness of the method in the diagnosis of gastric cancer.