Retrograde spread of cancer cells

Introduction Retrograde dissemination of cancer cells is one of the main symptoms of colorectal cancer tumor invasion and metastasis. Colorectal cancer is a general term for colon cancer and rectal cancer. Colorectal cancer refers to the occurrence of colonic mucosal epithelium under the influence of various carcinogenic factors such as environment or genetics. Malignant lesions have a poor prognosis and a high mortality rate. Colorectal cancer is a malignant tumor of the large intestinal mucosal epithelium. It is one of the most common malignant tumors of the digestive tract.

Cause

(1) Causes of the disease

The occurrence of colorectal cancer is the result of multiple genetic changes caused by various factors of genetic and environmental factors in the colonic mucosal epithelium. Many epidemiological studies of colorectal cancer have shown that the possible causes of colorectal cancer are socio-economic development, lifestyle changes, especially changes in dietary structure, and other factors such as environment and genetics.

Dietary factors

Epidemiological studies have shown that dietary factors are an extremely important factor in the pathogenesis of cancer, because 70% to 90% of cancer incidence is related to environmental factors and lifestyle, and 40% to 60% of environmental factors are To a certain extent, it is related to diet and nutrition.

(1) High-fat diet: A worldwide survey found that in countries with high colorectal cancer in North America, Western Europe, and Australia, people eat more than 120g of fat per day. In countries such as Poland, Spain, and Yugoslavia, where the incidence of colorectal cancer is high, the daily consumption of fat per person is 60-120g. In Colombia, Sri Lanka, Thailand and other places with low colorectal cancer, the daily fat consumption per person is only 20 to 60 g. The incidence of colorectal cancer in high and low incidence areas can vary by more than 6 times. The middle and low-incidence areas can differ by about 3 times. The fat content of Americans with high colorectal cancer accounts for 41.8% of total calories, and is mainly saturated fat. The Japanese with low colorectal cancer (the incidence of colorectal cancer is about 1 times lower than that of the United States), and the fat in the diet accounts for 12.2% of the total calories, and is mainly unsaturated fat. The correlation between the time trend of colorectal cancer incidence and dietary structure in Shanghai, China also shows that the change of colon cancer incidence rate is closely related to dietary structure changes.

Some animal studies have also confirmed that high fat intake can increase the risk of colorectal cancer. Reddy et al used induced dimethylhydrazine (DMH) to induce colorectal tumors in rats. The induction rate was 17% to 36% in the diet group containing 5% fat, and 64% to 67% in the diet group containing 20% fat. Significant difference. The results suggest that giving animals a high-fat diet can increase the incidence of colorectal tumors, make tumors appear earlier, increase the degree of malignancy and metastasis of tumors, and significantly shorten the survival time of tumor animals.

The reason why high-fat diets increase the incidence of colorectal cancer is:

A fat diet may cause colorectal cancer by altering the concentration of bile acid in the stool.

2 high fat and some sugars can increase the activity of intestinal bacterial enzymes (such as glucuronidase, ornithine dehydrogenase, nitroreductase, azolasin, lipoxygenase, cyclooxygenase) and promote carcinogenesis. The production of substances and cancers.

3 High-fat dieters often consume more meat, and meat can produce carcinogenic heterocyclic amines during frying or baking, which may lead to colorectal cancer.

(2) Low-fiber diet: Dietary fibre refers to plant polysaccharides and lignin that cannot be hydrolyzed by human digestive enzymes in plant foods.

The possible mechanism by which a high-fiber diet can reduce the incidence of colorectal cancer is:

1 dietary fiber can increase the volume of feces, dilute carcinogens, and shorten the intestinal transit time, reduce the contact between colonic mucosa and fecal carcinogens, thereby reducing the risk of colon cancer.

2 By inhibiting reabsorption, dilution and adsorption, chelation, reducing the deoxycholic acid concentration in the intestine, affecting intestinal lipid metabolism.

3 change the intestinal flora, affect the structure and function of intestinal mucosa, and affect the growth rate of mucosal epithelial cells, and mediate the pH of the intestine (usually the pH of feces in low-incidence areas of colorectal cancer is lower than that in high-incidence areas).

4 through mucin to strengthen the mucosal barrier, reduce intestinal toxic substances on the intestinal epithelium.

(3) Nitrosamine compounds: Many of the nitrosamine compounds are strong carcinogens, and tumors of various organs can be induced in animal experiments. Generally, small doses of nitrosamines can cause cancer if exposed for a long time. Nitrosamine compounds are widely found in food additives and preserved foods such as meat, fish, and vegetables treated with nitrite (such as bacon, ham, salted fish, etc.). Animal experiments have confirmed that nitrosamines can be converted into sputum by intestinal bacteria to cause colorectal cancer. Domestic Yanggong and other studies have found that the positive correlation between pickled foods is a separate risk factor for colorectal cancer. The risk of colon cancer ingested more than 3 times a week was 2.2 times (P < 0.01) for less than one case, 2.3 times for rectal cancer (P < 0.01), and 2.1 times for left colon cancer. Semi-colon cancer is 1.8 times.

(4) Vitamins: Case-control studies showed that carotene, vitamin B2, vitamin C, and vitamin E were all associated with a reduction in the relative risk of developing colorectal cancer. Statistical tests showed significant levels and showed a dose-response relationship. For example, Chiu et al. reported in 2003 that high intakes of vitamin C, carotene, and vitamin E were associated with a reduced risk of colon cancer. Mc Cullough et al. reported a follow-up observation of 60,866 men and 668,83 female participants in 2003, suggesting that vitamin D can reduce the risk of colorectal cancer in men (RR=0.71, 95% CI=0.51, 0.98), calcium in There is a protective effect in the development of colorectal cancer (RR=0.87, 95% CI=0.67, 1.12).

(5) Frying fried foods: The portion of the food roasted (fried) coke (especially meat) contains a carcinogen heterocyclic amine which acts on the colon and may cause colorectal cancer. The case-control study reported by Yang Gong et al. suggests that the carcinogenic effect of fried foods is also an independent risk factor. The risk of colon cancer ingested more than 3 times a week was 2.3 times (P < 0.01) for less than one case, 2.6 times for rectal cancer (P < 0.01), and 2.6 times for left colon cancer. Semi-colon cancer is 1.9 times.

(6) Onion and garlic: The protective effect of onion and garlic on tumor has been widely recognized, and the growth inhibition effect of this kind of food on tumor has been confirmed many times in the experiment. Garlic oil can significantly reduce the damage of colonic mucosal cells caused by dimethyl cholestyramine, and can reduce the induction rate of colorectal cancer in mice by 75%. Domestic Yanggong reported that the risk of colon cancer in high-incubation garlic food was 74% in the low-intake group (P<0.05), but the correlation with rectal cancer was not certain (OR=0.81, P>0.05). .

(7) Trace elements and minerals:

1 Selenium: Selenium is a trace element in the human body. It is a strong antioxidant. One of its most important biological functions is to inhibit the peroxidation reaction, and the peroxidation reaction can promote the carcinogen to the deoxyribonucleic acid. Several large-scale studies have found that mortality from multiple cancers, including nodules and rectal cancer, is inversely related to selenium intake in local diets. However, the influence of inorganic elements such as selenium on the etiology of human tumors may be affected by other food components (or interactions, or mixed, biased, etc.), so some people think that these factors may be just some accompanying factors, but not directly Affect the risk of colorectal cancer in the population.

2 Calcium: Animal experiments have shown that calcium can improve the toxic effects of deoxycholic acid on intestinal epithelium. Some scholars believe that the increase of the concentration of bile acids and free fatty acids in the intestine can promote the occurrence of colorectal cancer, and calcium can be combined with them to form insoluble saponified compounds, so that their stimulation and toxic effects on the intestinal epithelium are alleviated. Many epidemiological studies have also suggested that high calcium intake protects against the development of colorectal cancer. Yang Gong and other 1994 nutritional epidemiological studies showed that the protective effect of dietary calcium on colorectal cancer is not only related to intake, but also closely related to the food source of calcium. Among them, animal dietary calcium is related to the risk of reducing the incidence of colorectal cancer, while plant dietary calcium is not related to this. It is speculated that the calcium ions of different food sources may be different from the organic components of food, and may cause differences in the effects of calcium from different food sources.

3 Other inorganic elements: Studies have shown that potassium, iron, phosphorus and kidney, the risk of colorectal cancer is negatively correlated, zinc, magnesium, copper may affect the metabolism of carcinogens or degrade certain enzymes, which is related to the inhibition of cancer . But there is still a lack of more evidence to support. Some authors believe that these inorganic elements may have a mixed effect with some "vegetable" dietary factors (such as dietary fiber, vitamin C, etc.), or just some accompanying factors. Therefore, the impact of these inorganic elements on the pathogenesis of colorectal cancer needs further research.

2. Professional factors

Although it is generally believed that colorectal cancer is not an occupational disease, the relationship between occupational factors and the incidence of colorectal cancer still needs to be taken seriously. As reported by Donham et al. 1980, workers producing asbestos insulation in colorectal cancer patients are more common, and animal experiments have confirmed that asbestos fibers swallowed can penetrate the intestinal mucosa. In addition, in the metal industry, cotton yarn or textile industry and leather manufacturing industries, the standardized mortality and mortality of colorectal cancer is also higher. Domestic Gao Yutang passed the study on the relationship between occupation and tumor incidence in Shanghai in 1990, and pointed out that the ratio of standardized colon cancer incidence (SIR) of various professional and technical personnel was significantly higher (male = 135, P < 0.01; female = 147, P < 0.01). Female commercial workers had a colon cancer SIR=132, P<0.05. Colon cancer of male production workers, transport workers, etc. SIR=90, P<0.05.

3. Physical activity

In addition to occupational exposure and career-related.

an examination

Tumor infiltration and metastasis:

Local expansion is the most common form of invasiveness of colorectal cancer. Cancer cells invade surrounding tissues often cause corresponding symptoms, such as rectal cancer invading the sacral plexus and causing persistent pain in the lower abdomen and lumbosacral region, and anal incontinence. Due to the detachment of cancer cells, rectal examination can be carried out in the rectal fossa of the bladder or in the rectal fossa of the uterus, and ascites can occur in a wide range of dissemination. Early cancer can also spread along the lymphatic space around the nerve wall of the intestine, and later from the lymphatics to the lymph nodes. When the cancer cells metastasize to the para-aortic lymph nodes into the chyle pool, a left supraclavicular lymph node metastasis can occur through the thoracic duct, causing the lymph nodes to enlarge. A small number of patients have metastasized cancer cells due to blockage of the lymphatic vessels, and there are numerous diffuse small nodules in the perineum. In female patients, the tumor can be transferred to both ovaries and cause Kruken-berg disease. Advanced colorectal cancer can also be transferred to the liver, lungs, bones, etc. by blood.

an examination:

1. Fecal occult blood test: Fecal occult blood test is one of the early detection methods of colorectal cancer.

2. Carcinoembryonic antigen (CEA) examination: CEA does not have specific diagnostic value, both false positive and false negative.

3. Cellular and histological diagnosis: Pathological diagnosis is the basis necessary for definitive diagnosis and development of a treatment plan, including exfoliative cytology and pathological examination of biopsy tissue specimens.

4. Genetics: For more than 10 years, molecular genetics has revealed many genes related to tumorigenesis. People are paying more and more attention to molecular genetics and tumors.

5. Rectal mucus T antigen test: also known as galactose oxidase test, is a simple method to detect colorectal cancer and precancerous lesions specific markers, as long as the rectal finger is applied to a special paper film or slide, The galactose oxidase reaction and the Schiff's reagent color development can determine whether the patient's intestinal mucosa has T antigen expression.

Differential diagnosis

1. Right colon cancer

The prominent symptoms are abdominal mass, abdominal pain, and anemia. Some may have mucus or mucus bloody stools, frequent frequency, abdominal distension, intestinal obstruction, etc., but far less common than the left colon. In the right colon, the intestine is wide, and the primary cancer is often enlarged. It is more common with ulcers. Many patients can lick and mass in the right abdomen. Unless the cancer directly involves the ileocecal valve, intestinal obstruction is less common. Because the stool is still semi-fluid and thin in the right colon, the stool is still semi-fluid and thin in the right colon. Therefore, the bleeding caused by the friction of the stool is less, and most of the bleeding is due to cancer. Caused by swollen necrotic ulcer, because the blood and fecal fluid are evenly mixed and not easy to detect can cause long-term chronic blood loss, patients often seek medical treatment for anemia. Abdominal pain is also common, often painful, caused by a mass invading the intestinal wall. Secondary infection of cancerous ulcers can cause local tenderness and systemic toxemia.

2. Left colon cancer

The prominent symptoms are changes in stool habits, mucus or bloody stools, intestinal obstruction, and the like. The left colon is narrow, and the primary cancer is mostly infiltrated and grows, which tends to cause narrowing of the intestinal lumen, so constipation is more common. Subsequently, due to the increase in the upper end of the intestinal effusion, the peristalsis is hyperthyroidism, so diarrhea can occur after constipation, often appearing alternately. As the stool enters the left colon, it gradually becomes a lumpy shape. Therefore, the blood in the stool caused by the febrile friction is more common. The patient often seeks medical treatment earlier. The anemia caused by long-term chronic blood loss is not as prominent as the right colon. Intestinal obstruction caused by infiltration of the tumor into the intestinal wall is mostly chronic incompleteness. Patients often have long-term poor bowel movements and paroxysmal abdominal pain. Because of the lower obstruction, vomiting is not obvious.

Rectal cancer

The prominent symptoms are blood in the stool, changes in bowel habits, and associated signs of infiltration due to advanced cancer. The site of carcinoma in situ is lower, the fecal mass is harder, and the cancer is easily rubbed by the fecal mass and easily causes bleeding, mostly bright red or dark red, which is not mixed with the formed feces or attached to the surface of the fecal column and misdiagnosed "" bleeding. Due to the stimulation of the lesion and the secondary infection of the mass ulcer, it often causes defecation reflex and is easily misdiagnosed as "bacteria" or "enteric inflammation". The ring growth of the cancer causes the intestinal lumen to narrow, and the early manifestation is that the fecal column is thinned and the late stage is incomplete obstruction.

4. Tumor infiltration and metastasis

Local expansion is the most common form of invasiveness of colorectal cancer. Cancer cells invade surrounding tissues often cause corresponding symptoms, such as rectal cancer invading the sacral plexus and causing persistent pain in the lower abdomen and lumbosacral region, and anal incontinence. Due to the detachment of cancer cells, rectal examination can be carried out in the rectal fossa of the bladder or in the rectal fossa of the uterus, and ascites can occur in a wide range of dissemination. Early cancer can also spread along the lymphatic space around the nerve wall of the intestine, and later from the lymphatics to the lymph nodes. When the cancer cells metastasize to the para-aortic lymph nodes into the chyle pool, a left supraclavicular lymph node metastasis can occur through the thoracic duct, causing the lymph nodes to enlarge. A small number of patients have metastasized cancer cells due to blockage of the lymphatic vessels, and there are numerous diffuse small nodules in the perineum. In female patients, the tumor can be transferred to both ovaries and cause Kruken-berg disease. Advanced colorectal cancer can also be transferred to the liver, lungs, bones, etc. by blood.

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