What Is a Colon CT Scan?

Sigmoid colon cancer is a type of colon cancer. Early symptoms can include: abdominal pain, indigestion, abdominal distension, and abnormal bowel movements. The disease site is located in the colon between the descending colon and rectum.

Sigmoid colon cancer

Sigmoid colon cancer is a type of colon cancer. Early symptoms can include: abdominal pain, indigestion, abdominal distension, and abnormal bowel movements. The disease site is located in the colon between the descending colon and rectum.

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1. Age of onset. Most patients become ill after age 50.

2. Family history: If someone s first-degree relatives, such as parents, have had colorectal cancer, he is 8 times more likely to develop the disease in his lifetime than the general population, about a quarter of new patients. Has a family history of colorectal cancer.

3. History of colon diseases: Certain colon diseases such as Crohn's disease or ulcerative colitis may increase the incidence of colorectal cancer, and their risk of colon cancer is 30 times that of ordinary people.

4. Polyps: Most colorectal cancers develop from small precancerous lesions. They are called polyps, of which villous adenoma-like polyps are more likely to develop into cancer, and the chance of malignancy becomes about 25%; tubular adenoma-like The polyps malignancy rate is 1-5%.

5. Genetic characteristics: Some familial tumor syndromes, such as hereditary non-polyposis colon cancer, can significantly increase the incidence of colorectal cancer, and the onset time is younger.

1. The earliest stage may have symptoms of sigmoid colon cancer such as abdominal distension, discomfort, and indigestion, followed by changes in bowel habits, such as increased stool frequency, diarrhea or constipation, and abdominal pain before stool. Mucus or purulent bloody stools may appear later.

2. Symptoms of poisoning: due to tumor ulcers and blood loss and toxin absorption, patients can often cause symptoms of sigmoid colon cancer such as anemia, low fever, fatigue, weight loss, and edema, especially anemia and weight loss.

3. Symptoms of sigmoid colon cancer with intestinal obstruction: symptoms of incomplete or complete low intestinal obstruction, such as abdominal distension, abdominal pain, constipation or constipation. Physical examination showed abdominal distension, bowel type, local tenderness, and strong bowel sounds could be heard.

Sigmoid colon cancer 4. Symptoms of sigmoid colon cancer. Abdominal masses: tumors or masses that infiltrate and bind to the omentum and surrounding tissues. They are hard and irregular in shape, and some may have a certain degree of activity with the intestinal canal. In advanced stages, tumors Invasion is more severe, and the mass can be fixed.

When the tumor has reached a certain stage, especially when it has caused obstruction, a series of symptoms will be triggered. Including: weakness, fatigue, anemia, unexplained weight loss, persistent abdominal pain, black or bloody stools, and changes in bowel habits.

1.Fecal occult blood (FOBT) test

It is one of the main methods for early detection of colon cancer. In 1967, Greegor first used FOBT as a test for colon cancer in asymptomatic people. It is still a practical screening method. FOBT has chemical methods and immunological methods. Chemical methods include benzidine. Test and guaiacol test, etc., but the specificity is not ideal. Immunoassay methods include immune single expansion method (SRID), latex agglutination method (LA), convection immunoelectrophoresis (CIE), immunoenzyme method (ELISA) and reverse Indirect hemagglutination method (RPHA), etc., of which RPHA is more suitable for large-scale screening. The sensitivity of RPHA is 63.6%, which is lower than 72.7% of benzidine method, and the specificity of RPHA is 81.9%, which is higher than that of benzidine method. 61.7%, so RPHA as a preliminary screening can significantly reduce the number of re-screening population, and do not need to control diet, easy to be accepted by the census population.

2. Cytological diagnosis

Colon cancer exfoliation cytology methods include rectal flushing, brushing under colonoscopy, wire mesh balloon swabs, and finger smears at the lesion, etc., but clear-sight brushing at the colonoscopy or finger smears at the lesion site The film is more practical. If malignant cells are found to be of diagnostic significance, such as suspected malignant cells or nuclear heterogeneous cells with slightly larger nuclei and increased chromatin are not sufficient for the final diagnosis, but it is suggested that a review or biopsy should be performed to confirm the diagnosis. Exfoliated cells find malignant tumor cells, but the diagnosis of treatment should still be based on histopathological diagnosis.

3. Histopathological examination

Pathological examination of biopsy specimens is the necessary basis for the development of a treatment plan.

(1) Polyp-like mass: If the tumor is small, all the mass should be removed for examination, and the pedicle should be included. If there is no obvious tumor pedicle, the tumor's basal mucosa should be removed at the same time for examination.

(2) When performing biopsy on larger tumors, care should be taken to avoid clamping the necrotic tissue on the surface of the tumor. If possible, the tissue at the junction of the tumor base and the normal mucosa should be clamped as much as possible, especially if necessary. When the tumor becomes cancerous, it should be taken from multiple places.

(3) The tissue of the ulcer edge should be grasped by ulcerative lesions, and the degeneration and necrosis of the ulcer surface should not be taken.

During the production of small pieces of tissue, attention should be paid to the embedding direction of the mucosa to ensure that the longitudinal section of the glandular duct can be observed in the section.

4. Determination of serum carcinoembryonic antigen (CEA)

Gold was originally extracted from human colon and pancreatic cancer tissues with r-cell membrane glycoproteins in 1965. It was also found in endoderm-derived digestive tract adenocarcinoma and embryonic liver, intestine and pancreas tissues at 2 to 6 months. It is named CEA, and it is considered to be a specific measure of colon cancer. It has also been confirmed by subsequent work. CEA content in colorectal cancer tissues is clearly higher than that of normal tissues, showing that it is used as a basis for diagnosis. However, it has been widely used and further analyzed. It was found that CEA also exists in tumors such as gastric cancer (49% ~ 60%), lung cancer (52% ~ 77%), breast cancer (30% ~ 50%), pancreas (64%), thyroid (60%) and bladder, so CEA is indeed a malignant tumor-associated antigen, with the largest positive rate of colon cancer, especially in patients with liver metastases. It has been reported that CEA levels in portal vein and peripheral veins are significantly higher in 20 cases of colorectal cancer than in portal vein. The level of CEA in peripheral blood indicates that the liver has the effect of clearing CEA, but its mechanism is still unclear. In recent years, CEA measurement has been widely used in clinical practice, and its clinical significance can be summarized into 2 aspects:

Prediction of prognosis: Preoperative CEA can predict the prognosis, the recurrence rate of those with elevated CEA is higher, the prognosis is worse than the normal CEA value, the preoperative recurrence rate is 50%, the normal CEA is 25%, and the CEA is normal The value index is based on the sensitivity, specificity of different standards, and the correct index obtained from its predicted value. The correct index> 5µg / L is the highest (0.43), which is more suitable than other levels. Therefore, the enzyme standard method is 5µg / L. The normal value criterion is more appropriate.

Postoperative follow-up to predict recurrence or metastasis: For patients with elevated CEA before surgery, radical surgery should return to normal within 6 weeks or 1 to 4 months. Those who remain high may have residuals. Some people think that 10 weeks before the recurrence symptoms appear At 13 months, CEA has increased. Therefore, those who have increased CEA value after radical surgery should be closely examined and followed up. If necessary, a second surgical exploration is recommended. Moertal et al. (1993) reported 417 cases of recurrence. Serum CEA measurement 59% increased, while 16A increased in 600 cases without recurrence, showing a false positive, CEA is more sensitive to liver and retroperitoneal metastases, and relatively insensitive to lymph node and lung metastases, the authors counted 115 cases of CEA increased. For laparotomy, 47 cases had recurrence (40.1%). Martin reported that 60 cases had reoperation according to CEA elevation, 93.3% confirmed recurrence, 95% liver metastasis had elevated CEA, and generally 17% to 25% had metastasis or recurrence. CEA levels are normal. CEA-led second laparotomy is currently the best method to improve the survival rate of recurrent colorectal cancer.

5.Gene testing

With the study of tumor molecular genetics, the development and application of polymerase chain reaction (PCR) in vitro gene amplification technology has provided the possibility for tumor gene diagnosis. Currently, polymerase chain reaction-limiting fragment length has been developed. Polymorphic analysis (PCR-RFLP) method can detect single-molecule DNA or samples containing only one target DNA molecule per 100,000 cells. It has been studied and applied in colon cancer in the following two aspects.

(1) Determining the mutation rate of Ki-ras gene in colorectal cancer and adjacent tissues: it is helpful to understand the degree of tumor malignancy, and to participate in predicting its prognosis. There are many human tumors in the ras gene, which is a potential tumor marker. Point mutations can turn the ras gene into an oncogene. Gan Yuebo and others detected the 12th codon mutation in 35 cases of colorectal cancer in China (31.4%) and 61 cases in 1 case (2.9%). In one case, only the codon 12 mutation in the adjacent tissue was found, but the 13th codon Gly AsD mutation, which is more common in colon cancer in this paper, was not found (Table 4). This method can be further studied and promoted for the identification of small tissues. Cancer is helpful.

(2) Detection of mutated Ki-ras gene in feces: Qian Yuebo, etc., isolated macromolecular DNA from feces and carried out PCR amplification of exon 1 of Ki-ras gene. RFLP was used to detect the presence of 12 codons in the gene. There were no mutations. Six of the 18 colorectal cancer patients were found to have Ki-ras gene mutations (33.3%). Four of them also found corresponding mutations in cancer tissues. Volgelstein et al. Examined stools of 24 suspected colon cancers, 9 The ras gene was found in 8 cases and the mutation was found in 8 cases. The detection method can be used for the surveillance of highly suspicious and general methods failed to detect the population, and has practical application prospects for early detection of colorectal cancer.

6.Fiber colonoscopy

The application of fiber colonoscopy is an important progress in the diagnosis of colon tumors, which has also improved the early diagnosis rate. The application of short fiber sigmoidoscopy has gradually replaced the examination of 30cm rigid sigmoidoscopy. The rate of cancer lesions is 2 times higher than that of rigid mirrors, and the rate of adenomas is 6 times higher. Because fiber sigmoidoscopy is easy to grasp and apply, it has been widely used in census high-risk populations. Endoscopy, visual inspection and biopsy In addition to pathological diagnosis, it can also perform removal surgery on pedicled lesions in different parts. For those who are difficult to determine by X-ray examination, the microscopy can further confirm the diagnosis. In addition to confirming the symptomatic patients, it is also used to screen asymptomatic people at high risk. .

7. Imaging diagnosis

The purpose of imaging examination is to detect invasion and metastasis. The estimation of the depth of invasion is extremely important. The rate of tumor metastasis is limited to 6% to 11% of those with submucosa, and 10% to 20% beyond those with submucosa. 33% to 50%.

(1) Double contrast imaging of colonic barium:

It is an important test for colon disease, but it should not be used as a general survey of the population. The dual air-barium contrast angiography is significantly better than the results of a single barium contrast examination. The former detection rate can reach 96%, which is similar to colonoscopy. Thoeri and Menuk report double The radiographer had an error rate of 11.7% for small colon polyps and 45.2% for single barium radiography; the detection rates of polyps were 87% and 59%, respectively. In experienced persons, the detection rate of double radiography can reach 96 %, Which is close to the result of colonoscopy, but X-ray angiography is also inadequate. It can cause false negatives due to stool or sigmoid colonic disc turnover. The false negative rate can reach 8.4%.

Check points: cleansing the bowel should not be used for cleansing and bowel preparation. Oral laxatives should be added to the slag-free diet, and the feces should be removed.

Intravenous injection of 70% -80% barium sulfate with drug (654-2), so that the colon was hypotonic, barium agent was injected under perspective until hepatic curvature was displayed, and then gas was injected to achieve abdominal distension.

The subjects change their positions, adopt supine and left and right oblique positions, upright and supine positions, right anterior oblique positions, etc. to fully display the left half, right half, cecum and other parts, pay attention to observe whether there is filling defect, intestinal wall stiffness and Narrowness, shadow, and special signs of malignancy should be noticed in the diagnosis, such as: whether the head of the polyp is stiff, ulcerated, and the intestinal wall shrinks at the base (Figure 4); observe the presence of cancer in other parts of the colon Small polyps; familial adenoma may be considered in those with multiple polyps in those under 40 years of age.

(2) CT scan:

Observation of morphological changes in the colonic cavity is generally better than CT with gas-barium enema examination. However, CT is helpful to understand the extent of cancer invasion. CT can observe the thickening of the bowel wall and highlight it, but it is sometimes difficult to identify benign ones earlier. With malignancy, the biggest advantage of CT is to show the involvement of adjacent tissues, whether the lymph nodes or distant organs have metastasized, so it is helpful for clinical staging. The CT staging method proposed by Moss et al .:

Stage 1: The thickness of the digestive tract wall is normal (usually 5mm), and polypoid lesions protrude into the cavity.

Phase 2: The wall of the tube is locally thickened, showing uniform plaques or nodules, without wall expansion.

Phase 3: Local thickening of the tube wall, direct invasion of surrounding tissues; limited or regional lymph node involvement, but no distant metastasis.

Stage 4: There are distant metastases (such as liver, lung, distant lymph nodes).

Therefore, CT examination is helpful to understand the tumor range, to help preoperative staging, to estimate the range and to formulate a treatment plan, and it is also one of the indicators for estimating the prognosis. Therefore, CT examination has been used as one of the routine examination methods, but some materials have proposed CT surgery. The accuracy rate of pre-stage staging is 48% to 72%, and the accuracy rate of lymph node metastasis is estimated to be 25% to 73%. It may seem difficult to use as a routine test for staging, but it is more meaningful for the detection rate of liver or metastatic nodules.

(3) MRI:

The diagnosis of intestinal tumors is still unclear. MRI can make up for the lack of CT diagnosis. MRI is easy to understand the fat infiltration around the rectum, so it is helpful to find or identify stage 3 patients.

Diagnosis is based on clinical manifestations and laboratory tests.

The treatment of sigmoid colon cancer first emphasizes surgical resection, and pays attention to combined preoperative chemotherapy and radiotherapy to improve the surgical resection rate, reduce the recurrence rate after surgery, and improve the survival rate.

Diet for patients with sigmoid colon cancer

1, should pay attention to eat more vegetables and fruits rich in dietary fiber, such as spinach, rape, cabbage, celery, leek and radish and other green leafy vegetables, as well as fruits, etc. to maintain smooth stool, reduce the contact time between carcinogens in the stool and colonic mucosa .

2. Colon cancer bulges into the intestinal cavity, and when the intestinal cavity becomes narrow, it is necessary to control the intake of dietary fiber. At this time, it is necessary to give digestible and soft semi-fluid foods, such as millet porridge, thick rice noodle soup, rice soup, porridge. , Corn porridge, custard, tofu brain and so on.

3. Eat more fresh vegetables and fruits.

4. Reduce the intake of fat and animal protein in food. It can reduce the carcinogen production and carcinogenesis of its decomposition products to reduce the potential danger of colon cancer.

5. Avoid irritating food such as cold and spicy.

6, avoid tobacco and alcohol.

Postoperative care of sigmoid colon cancer If the patient has weight loss, pain in the sacrum, lumps of the perineum, abdominal mass, ascites, and liver enlargement, he should go to the hospital in time. Patients with anal reconstruction due to surgery for early detection of metastasis and other conditions, because the artificial anus does not have sphincter muscles, and the body has abnormal smells, patients often have a burden of thought, so they should explain and encourage more, and help and guide patients to do a good job Artificial anal care.