Gastric fluid analysis Normal gastric fluid is colorless or light yellow, with free hydrochloric acid about 0-10 U per 100 ml of gastric fluid and total acidity about 10-50 U. The gastric acid of gastric cancer patients is mostly low or no free acid, about 65% of gastric cancer patients show gastric acid deficiency, while 200%-25% of patients still show gastric acid deficiency after stimulation by pentagastrin, and the degree of low gastric acid is often proportional to the size of gastric cancer. The degree of hypogastric acidity is often proportional to the size of gastric cancer. When gastric cancer causes pyloric obstruction, a large amount of food residue can be found, and if it is accompanied with bleeding, coffee-like liquid can appear, which is of certain significance for the diagnosis of gastric cancer.
2.Fecal occult blood test A positive persistent fecal occult blood test has reference value for the diagnosis of gastric cancer and can provide clues for the detection of gastric cancer. The positive rate of fecal occult blood test in early superficial gastric cancer can reach 20%, and with the progress of the disease, its positive rate can reach more than 80%, among which the positive rate is highest in gastric body cancer and second in cardia cancer.
3.Immunological diagnosis There are many methods of examination, which have been used clinically in China. Monoclonal antibodies made by applying cell fusion to establish hybrid cell cancer cell lines have been applied to diagnose and treat tumors at home and abroad. The research of monoclonal antibodies for gastric cancer diagnosis started earlier, and some of them have been applied in the clinic.
(1) Serum diagnosis and body fluid diagnosis: gastric cancer has tumor-associated antigens, and the application of monoclonal antibodies can detect these associated antigens. In general, if the serum CEA exceeds 50ng/ml (normal <15ng/ml) or CA-19-9 exceeds 200U/ml (normal <25u/ml), the gastric cancer is already in advanced stage and the prognosis is not good. peritoneum is involved. Its detection value can be decreased when chemotherapy is effective, so it can be used to judge the efficacy of chemotherapy. However, it does not seem to have much significance for the diagnosis of early gastric cancer, and there are false positives and false negatives, and crossover with other tumors.
Recently, more monoclonal antibodies such as MG5, MG7, MG9, MGb1 and MGdl have been reported in China, which can be used to detect glycolipid and glycoprotein antigens in serum, and the positive rate has been improved, especially the results of series of mixed tests are more accurate. The test methods include radioimmunoassay, enzyme-linked immunoassay and hemagglutination assay, which can not only identify serum tumor-associated antigens, but also detect related antigens in gastric fluid and ascites.
There are also some anti-pancreatic cancer monoclonal antibodies that can also be used for qualitative examination of gastric cancer, such as PS1 and PS7.
Most of these tests are used to determine the prognosis of tumors or the efficacy of chemotherapy, and further research and exploration are needed for the diagnosis and differential diagnosis of gastric cancer.
(2) Pathological immunohistochemical diagnosis: monoclonal antibodies against gastric cancer are used to stain tissue sections by immunohistochemical methods such as ABC method and PAP method, and the positivity rate can reach 82.5% to 92.5%. It has improved the diagnosis of gastric cancer and the diagnosis of lymph node metastasis. In addition, it can also be used as an auxiliary indicator of precancerous lesions and the risk of carcinogenesis of intestinal adenosis. The monoclonal antibodies that have been reported to be used in this operation technique are MG7, MGdl, RWS4 and 83YH2.
(3) Fetal sulfoglycoprotein antigen (FSA): FSA is one of the three sulfoglycoprotein antigens in gastric juice. Hakkinen (1969) used agar diffusion method to detect 78 cases of gastric cancer and 75 cases were positive, with a positive rate of 96.1%. In the Capital Hospital, 33 cases of gastric cancer were examined by this method and 28 cases were positive, with a positive rate of 84.8%.
(4) Gastric cancer antigen (GCA): GCA is a tumor-associated antigen, which exists in gastric juice of gastric cancer patients and is a glycoprotein with immunological activity. Beijing Institute of Biological Products and Shanghai Sixth People’s Hospital have tested 20 cases of gastric cancer patients’ gastric juice by agar diffusion method, and the positive rate was 85% and 80% respectively.
(5) Radioimmunoimaging diagnosis: Anti-gastric cancer monoclonal antibody is injected into the patient after 131I labeling, and single photon emission body scan or mechanical scan with γ camera after 48-72h can show the primary lesions and metastases, and accurate localization images can be obtained, and the satisfactory image display rate can reach 70%-80%. It is helpful to guide the scope of surgical resection.
(6) Cytological diagnosis: gastric exfoliative cytology examination, immunofluorescence or immunoenzymatic cytology examination of cancerous pleural fluid and ascites by applying monoclonal antibody can greatly improve the detection rate of cancer cells, reaching 89.4%. At present, there are several clinical sampling methods as follows.
①General flushing: the day before the examination, the patient should eat liquid juice for dinner and fast in the morning of the same day, empty the gastric juice under the gastric tube, then flush with saline repeatedly, and let the patient change the position, and finally collect the flushing fluid. After centrifuging the rinsing fluid, take the sediment for smear, staining and microscopic examination.
②Rinsing method under direct vision: rinse the suspected lesion with fiberoptic gastroscope under direct vision, and then aspirate the rinsing fluid with a catheter for examination.
③Brush method: Under direct vision of fiberoptic gastroscope, the suspicious lesion is rubbed back and forth with a nylon cytology brush and then removed for smear microscopy. In the brush smear cytology specimen, normal gastric surface epithelial cells were arranged in clumps, with regular cell clusters and accompanied by honeycomb manifestations, round nuclei of individual cells, and uniform chromatin distribution. Cancer cells were usually distributed singly or in small irregular clusters with large cells, distorted deep stained nuclei, and contained multiple or huge nucleoli.
④Printing method: biopsy under direct vision of fiberoptic gastroscopy, remove gastric mucosal tissue and smear it on a slide for microscopic examination.
Gastric exfoliative cytology is a better method to diagnose gastric cancer, with simple operation, high positivity rate and less pain. It is easy for patients to accept. However, it cannot determine the location of lesion, so it should be used in combination with X-ray, gastroscopy and other examinations.
4.Tetracycline fluorescence test There are many methods of tetracycline test, but the basic principle is based on the feature that tetracycline can combine with cancer tissue. For example, tetracycline is taken up by gastric cancer tissues after entering the body, thus fluorescent substances can be seen in the precipitation of gastric lavage fluid. Methods: Tetracycline 250mg was administered orally 3 times a day for 5 days, and the stomach was lavaged 36h after the last dose. The gastric washings were collected and centrifuged, the sediment was spread on filter paper, dried in a greenhouse, and observed in a dark room with fluorescent light, and those with yellow fluorescence were considered positive. The positive diagnostic rate was 79.5%.
The average zinc content in gastric cancer tissues is 11,400mg/kg, which is 2.1 times of the zinc content in healthy tissues. The zinc in the cancer cells is mixed with shed cancer cells in the gastric juice of gastric cancer patients, and after the action of gastric acid and enzymes, the zinc in the cancer cells is freed from the protein-bound state and mixed into the gastric juice in an ionic state. Therefore, the zinc ion content in gastric juice of gastric cancer patients is increased. Hangzhou Cancer Hospital used diphenyl aminothiourea as qualitative reaction at pH 5.5 of gastric juice. Among 88 patients with pathologically confirmed gastric cancer, 77 cases were positive, with a positive rate of 87.5%.
6.Other tumor markers
(1) Polyamines: In recent years, polyamines have been reported to be related to the biological behavior of gastric cancer and identified as one of the malignant tumor markers. The urinary polyamine level of gastric cancer patients is significantly higher than that of normal patients and benign gastric cancer patients; it is positively correlated with clinical stage.
(2) Glycyl prolyl dipeptidyl aminopeptidase (SGP-DA): SGPDA viability assay is valuable in identifying the benign and malignant nature of the lesion.
(3) Cellular nuclear DNA content: Gastric mucosal biopsy sections for cellular nuclear DNA content determination showed a non-holistic DNA detection rate of 71% to 92% for gastric cancer, while benign lesions and mucinous carcinoma were diploid.
7.Gastroscopy Due to the development and common application of fiber endoscopy technology, the diagnosis rate of early gastric cancer has been significantly improved. The 5-year survival rate of early gastric cancer can reach over 90% after surgery, and the prognosis is better if it can be diagnosed early. Gastroscopy is intuitive, accurate and can detect small gastric mucosal lesions. The wide use and popularization of gastroscopy is the key to improve the early detection rate of gastric cancer. Some data show that the sensitivity, specificity and accuracy of gastroscopy combined with biopsy can reach 93.8%, 99.6% and 97.4%, respectively, in the diagnosis of gastric cancer. Japan is a world leader in the early detection of gastric cancer, which is related to the wide application of gastroscopy. In recent years, in addition to the improvement of the performance of general fiber gastroscopy, electronic gastroscopy, ultrasound gastroscopy, pigmented gastroscopy and magnifying gastroscopy have also been gradually introduced into clinical practice.
Endoscopy can directly observe all parts of the stomach, which is of great value for the diagnosis of gastric cancer, especially for early gastric cancer.
The early gastric cancer augmentation type mainly shows local mucosal elevation, protruding into the gastric lumen, with a tip or broad base, rough surface, some are papillary or nodular, and there may be erosion on the surface. The superficial type presents with irregular boundaries, obscure localized mucosal roughness, slightly elevated or depressed, with a pale or reddish surface, and may have vesicles, and these lesions are most likely to be missed. The depressed type has more obvious ulcers, and the depressions mostly exceed the mucosal layer. All the above types can be combined to form a mixed type of early gastric cancer.
There is a half spherical polyp-like elevation in the middle of the gastric body with smooth surface, hard texture, about 1.5 cm in diameter, wide base, intact surrounding mucosa, no edema, no infiltration, a bulge in the posterior wall of the anterior pyloric region, partly nodular, pale, with an irregular shallow ulcer in the center, which is pathologically confirmed as adenocarcinoma.
8.Middle and late stage gastric cancer often has typical manifestations of gastric cancer, and endoscopic diagnosis is not difficult. The lesion of augmented type is larger in diameter, irregular in shape and cauliflower or chrysanthemum-like.
(1) Fiber gastroscopy: domestic fiber gastroscopy has been popularized to county hospitals, which has greatly improved the diagnosis level of gastric cancer. Gastroscopic diagnosis of middle and late stage gastric cancer is not difficult, but the diagnosis of early stage gastric cancer whose lesions are limited to mucosa and submucosa layer is not easy. The detection rate of early gastric cancer still varies greatly among different hospitals, and the composition ratio of early gastric cancer to the total number of gastric cancer cases can be as high as 18.0% and as low as 1.2% to 2.7%, with an average of only 10%. Since early gastric cancer often has no specific symptoms, in order to improve the early detection rate, the indications for gastroscopy should be appropriately relaxed and the gastroscopic features of early gastric cancer should be familiar.
(1) Bulging type: It mostly occurs in the anterior pylorus, the vicinity of cardia and the posterior wall of the upper part of the stomach body. The mucosa is raised in the form of polyps with uneven, red or erosion surface, and there is often no clear demarcation with the surrounding normal gastric mucosa.
②Flat type: the lesion is slightly raised or lower than the surrounding mucosa, and its main feature is the change of color of the surrounding mucosa and the rough and irregular granular feeling. The mucosa of the lesion can be limited or more widely reddened, discolored or discolored, and the diagnosis of this type is generally more difficult with the naked eye.
(3) Depressed type: It is usually found in the anterior pyloric region, the side of the greater curvature of the gastric sinus and the cardia. The depressed area is clearly demarcated from the surrounding normal mucosa, and the mucosal folds of the lesion are irregularly uneven, losing the luster of the normal mucosa and having abnormal redness or discoloration and other color changes, and there are often dirty exudates or bleeding spots, and the mucosa gathered in the depressed area can suddenly become thin or irregularly thickened or even abruptly interrupted, and the marginal mucosa often has nodular and untidy particles.
Since the diagnosis rate of superficial gastric cancer by gastroscopic visual examination is not high, only about 70%. Therefore, biopsy or cytological examination is necessary to make a definite diagnosis, and correct sampling site and skilled operation technique are the keys to the success of biopsy. The positive biopsy rate ranged from 30% to 94.4%, and the overall positive biopsy rate was 82.96%.
In addition to the above three types, clinical reports of a special type of early gastric cancer, Gastritis-like type of EGC, are increasing day by day, and the retrospective data show that this is a fast-growing type of cancer, which mainly shows receding color, congestive changes and uneven mucosa under endoscopy. Therefore, it is very important to improve the recognition of this type of lesion under endoscopy and to take correct biopsy material for timely diagnosis.
(2) electronic gastroscope: has the advantages of high image resolution, multiple simultaneous observation, convenient data storage and output, etc. Some also have digital inspection device, with functions such as magnification, contrast enhancement, negative imaging, pseudo-coloring, edge enhancement, etc., and the size and color of the lesion can be determined by the image analysis system. At present, domestic electronic gastroscopy has begun to popularize to county hospitals.
(3) Ultrasonic gastroscopy: Ultrasonic gastroscopy is a micro-ultrasound probe mounted on the front of fiber gastroscope, and ultrasound examination is performed in the stomach cavity, which can not only directly observe the gastrointestinal mucosa through the gastroscope, but also use ultrasound to probe the structure of the gastrointestinal wall and adjacent organs, thus expanding the diagnostic function and scope of gastroscopy, while ultrasound scanning in the gastrointestinal cavity obviously shortens the distance between the ultrasound probe and the target organ, avoiding the abdominal wall fat At the same time, the distance between the ultrasound probe and the target organ is significantly shortened due to the ultrasound scanning in the gastrointestinal cavity, which avoids the influence of abdominal wall fat, intestinal gas and skeletal system on ultrasound interference, thus significantly improving the resolution and accuracy of ultrasonic diagnosis. At present, many large hospitals in China have been equipped with ultrasound gastroscopy.
Usage: The preoperative preparation and examination methods are the same as those of ordinary gastroscopy. When the site of investigation is reached, airless water must be injected into the stomach, or a rubber capsule is installed at the probe, and airless water is injected into the capsule so that the capsule is close to the esophagus, stomach wall and intestinal wall for ultrasound examination, so that the ultrasound is not absorbed in the air and attenuated in large quantities.
Ultrasound gastroscopy can divide the stomach wall into five layers: mucosal layer, mucosal muscle layer, submucosal layer, intrinsic muscle layer and plasma membrane interface layer. The sonogram of early gastric cancer varies according to different types. The flat type of gastric cancer has thickened mucosa with hypoechoic area, while the depressed type has partial defects in the mucosal layer and can invade the submucosal layer. In progressive gastric cancer, different changes in the five echogenic bands can be used to help identify the depth of infiltration of gastric cancer, and sometimes even metastatic lymph nodes with round strong echogenic masses outside the gastric cavity can be detected.
Ultrasound gastroscopy is important in the diagnosis of invasive gastric cancer, the depth of infiltration and the metastasis of nearby lymph nodes, and it is superior to body ultrasound and CT in determining the clinical stage of gastric cancer. In addition, it has important diagnostic significance for submucosal tumors. In 641 cases of gastric cancer reported by Yasuda in Japan, the compliance rate between the depth shown by ultrasound gastroscopy and histological examination after surgery was 79.6%, including 84.9% for early gastric cancer and 55.8% for local lymph node detection, but it is still difficult to determine ulcerative lesions and to differentiate benign and malignant smooth muscle tumors. In the United States, Karpen applied ultrasound gastroscopy for TNM staging of gastric cancer and found that the risk of recurrence of T3 gastric cancer after surgery was great. Shanghai Changhai Hospital in China reported 8 cases of early gastric cancer, 2 cases were completely accurate, 3 cases were basically accurate and 3 cases were wrong. It is believed that ultrasound gastroscopy is better than gastroscopy in judging early gastric cancer, but it is difficult to distinguish whether the hypoechoic foci are inflammation, fibrosis or tumor.
(4) Pigmented gastroscopy: pigmented gastroscopy is to spray dye on the suspected lesion while examining by ordinary gastroscopy, using certain dyes to stain the tissue, so as to improve the ability to identify cancerous lesions under gastroscopy, reduce the blindness of biopsy sampling, improve the detection rate of early gastric cancer, and also help to determine the scope of surgical resection. Tatsuta et al. reported that in 56 cases of small gastric cancer, the positive rate of conventional gastroscopy was only 25%, while the positive rate increased to 75% using methylene blue-Congo red staining. There are two commonly used methods.
① Spraying method: first take mucus remover to remove mucus in the stomach, insert a plastic tube through the gastroscopic biopsy orifice, spray 0.5%~0.7% methylene blue directly onto the gastric mucosa to be observed, rinse off the staining solution with distilled water after 2 min, then observation can be made, and the lesion mucosa is stained. This method is mostly used to observe the enteric lesions of the gastric mucosa or duodenal mucosa.
② oral method: take mucus scavenger and 100-150mg US blue capsule at the same time, let the patient rotate the position and fully move for 1.0-1.5h within 30min, so that the solution can contact the whole gastric mucosal surface, then perform gastroscopy to observe the mucosal coloring and take biopsy in the coloring area. This method is used for the examination of gastric cancer.
(5) Enlargement of large gastroscope: it can be magnified 35 times and is often used to observe various changes of gastric mucosal sink. With this scope, the morphology of gastric pits can be divided into 7 types, such as A (small granular type), B (broken line type), C (continuous line-like groove), D (circular reticular groove), mixed type AB, BC and CD. The microscopic morphology of gastric mucosa varies in different diseases, and the normal fundic mucosa is type A, which becomes type B and C in atrophic gastritis. The normal mucosa of the pylorus is fine C type and becomes coarse C type in atrophic gastritis. Highly differentiated gastric cancer shows characteristic C-shape, while low-differentiated gastric cancer has uneven surface and small concave absence. d-shape suggests past mucosal destruction and regeneration, mostly seen in erosion and ulcer scar. Hyperplastic polyps have a soft and swollen appearance with no change in mucosal structure.
9.Barium X-ray examination Barium X-ray examination for gastric cancer has a history of more than 70 years, and it is still one of the important methods to diagnose gastric cancer. The misdiagnosis rate of general conventional gastrointestinal examination is high, often reaching 20%-30%, and the surgical resection rate of detected gastric cancer does not exceed 50%, and the 5-year survival rate after resection is less than 20%, and it is even more difficult to detect superficial gastric cancer. In recent 10 years, due to the use of double contrast gas-barium imaging, low-tensor imaging technique, compression method and high-density barium powder, the fine structure of mucosa can be clearly displayed, which is conducive to the detection of microscopic lesions, reducing the misdiagnosis rate of gastric cancer, improving the detection rate of superficial gastric cancer, and detecting intra-mucosal cancer with lesion diameter of only 1 to 2 cm. For those who suspect early gastric cancer, they should take more X-rays from different angles and analyze them carefully so as not to miss the small changes.
The X-ray manifestations of early gastric cancer are as follows
(1) Elevated type: the lesion is elevated above the mucosal surface and appears as a lobulated or myxoid mass lesion convex into the gastric cavity, the surface of the mass is uneven, and it appears as an irregular filling defect in the barium pool. A confined filling defect with a larger volume and a broader base, a rough irregular granular surface, a lobulated shape or a basin-like depressed area on the raised mucosal surface are all features of malignancy.
(2) Flat type: It is not easy to show under X-ray, and sometimes the application of low-sheet double contrast photographs can see abnormal barium attachment on the gastric mucosa or irregular shape of the mucosal folds.
Infiltrative type: Infiltrative gastric cancer can be divided into diffuse type and limited type. Diffuse infiltrating gastric cancer can involve the large part of the stomach or the whole stomach, and barium X-ray imaging shows flattening and disappearance of gastric mucosal folds, obvious shrinkage of gastric cavity, stiffness of gastric wall, and disappearance of peristalsis, which is like a leathery capsule, called “leathery stomach”; or only diffuse abnormal mucosal folds are found and misdiagnosed as chronic gastritis; limited infiltrating gastric cancer can occur in any part of the stomach. It can occur in any part of the stomach, and barium x-ray imaging mainly shows limited gastric wall stiffness and limited, fixed narrowing of the gastric lumen, or tubular narrowing in severe cases, which is commonly seen in infiltrating gastric sinus cancer (Figure 11).
(3) Depressed type: The double contrast imaging shows a large annular irregular shadow surrounded by an irregular ring dike, forming a “double ring sign”, with the outer ring being the edge of the tumor and the inner ring being the edge of the tumor surface ulcer. In the filling phase compression photograph, ulcerated gastric cancer may show typical “half-moon syndrome”, including niche shadow located in the lumen, large and shallow niche shadow, often in the shape of half-moon, surrounded by a translucent band of varying widths, i.e. ring dike, separating it from the adjacent gastric lumen; “finger pressure sign” and “slit sign” can be seen at the mouth of the niche shadow. “The niche is surrounded by a translucent band of equal width, i.e. a ring dike, which separates the niche from the adjacent gastric lumen; “finger pressure sign” and “slit sign” can be seen at the mouth of the niche, and the mucosal folds around the niche are interrupted and destroyed. Filling phase and double contrast phase can be clearly shown.
The niche or depression with irregular jagged edges and a granular base, with sudden narrowing, terminal truncation or pestle-like thickening of the surrounding mucosal folds. In this type, attention should be paid to the early carcinogenesis of benign ulcers. If there is pestle-like interruption of individual mucosal folds around the mouth of the niche shadow, finger pressure signs in the mouth, nodular filling defects inside and outside the mouth, etc., they are all signs of early cancer.
It is not difficult to diagnose middle and late stage gastric cancer by X-ray, and the diagnosis rate can reach over 90%. The mass type mainly shows irregular filling defects protruding into the lumen. The ulcer type mainly occurs on top of the mass, so its niche shadow is located within the gastric contour, often larger than 2.5 cm in diameter, with irregular edges, sometimes half-moon shaped, interrupted surrounding mucosal folds, and a wider range of peristaltic disappearance. The infiltrative type mainly shows stiffness of the gastric wall, loss of peristalsis, narrowing of the gastric lumen, loss of mucosal folds, and extremely rapid discharge of barium. If the whole stomach is involved, it is “leathery stomach”.
10.CT examination Before CT examination, a certain amount of 1% pantothenic glucosamine is taken orally to make the stomach dilate. The thickness of normal gastric wall is usually 2~5mm, while gastric cancer shows irregular thickening of restricted or extensive gastric wall, often more than 10mm, and nodular, polyp-like or lobulated soft tissue masses can be seen protruding into or out of the lumen, and can show narrowing of gastric lumen, soft tissue masses or ulcer images. In addition, it can usually show nearby organs such as liver, pancreas, spleen, gallbladder, colon, ovaries, and adrenal glands, which can determine the extent of spread and metastasis of gastric cancer.