Rectal Cancer

　　With the improvement of people's living standards, reasons such as overly refined food, lack of exercise, and other factors have caused the incidence of rectal cancer to continue to rise.

　　Chronic Rectal InflammationChronic ulcerative colitis, chronic schistosomiasis, and granulomas formed by chronic blood fluke disease are directly related to the occurrence of colorectal cancer. The longer the course of the disease, the higher the possibility of developing colorectal cancer, and the incidence of colorectal cancer in patients with ulcerative colitis for more than 20 years is about 20% to 40%.

　　Carcinoma of Rectal AdenomaRectal adenomas refer to the protruding lesions on the surface of the rectal mucosa into the intestinal cavity, including adenomas (including villous adenomas), juvenile polyps, inflammatory polyps, and polyposis, etc.

　　Diet and CarcinogensEpidemiological studies show that the occurrence of colorectal cancer is obviously related to economic conditions and dietary structure. In economically developed areas, regions and groups with a high proportion of animal fats and proteins in their diet and a low fiber content have a significantly higher incidence. The exact mechanism of the relationship between dietary structure and the occurrence of colorectal cancer is not yet fully clear. It is generally believed that it may be related to factors such as the metabolites of animal fats, bacterial decomposition products, and the increased absorption of toxins in the intestines due to the slow intestinal peristalsis under a low-fiber diet state.

　　Genetic FactorsExcluding colorectal cancer patients with familial polyposis syndrome or ulcerative colitis with malignant transformation, about 5% to 10% of other colorectal cancer patients have a significant family history of cancer, collectively known as hereditary non-polyposis colorectal cancer, also known as Lynch syndrome.

　　The common complications of colorectal cancer patients mainly include colon obstruction and intestinal perforation. The prognosis of colorectal cancer is not related to the patient's gender and age, but is closely related to the course of the disease, the extent of tumor infiltration, differentiation degree, and whether there is metastasis.

　　1. Colon obstruction: It is one of the late complications of colorectal cancer, which can occur suddenly or gradually. It is often caused by tumor growth blocking the intestinal lumen or narrowing of the intestinal lumen, or it can also be caused by acute inflammation, congestion, edema, and hemorrhage at the tumor site.

　　2. Intestinal perforation: There are two situations for perforation in colorectal cancer: perforation occurs locally in the tumor; or perforation of the proximal colon, which is a complication of tumor obstruction. After perforation, clinical manifestations may include diffuse peritonitis, localized peritonitis, or the formation of a local abscess. Diffuse peritonitis is often accompanied by toxic shock, with a very high mortality rate.

　　Early-stage colorectal cancer is mostly asymptomatic, while patients with advanced cancer (middle and late stages) may experience symptoms such as abdominal pain, hematochezia, thin stool, and diarrhea.

　　Typical symptoms of colorectal cancer patients

　　1. When colorectal cancer grows to a certain extent, symptoms such as hematochezia may appear. Small amounts of bleeding are not easily visible to the naked eye, but a large number of red blood cells can be found in the stool when examined under a microscope, known as positive occult blood test in stool. With a large amount of bleeding, stool may contain blood, which can be bright red or dark red. When the surface of the tumor breaks, forms an ulcer, and the tumor tissue necrotizes and becomes infected, pus and mucus-containing blood stool may occur.

　　2. Patients may have varying degrees of incomplete defecation, anal坠感, and sometimes diarrhea.

　　3. When rectal tumors cause intestinal stricture, symptoms of varying degrees of intestinal obstruction may occur (abdominal pain, bloating, difficulty defecating), with abdominal pain and intestinal rumbling before defecation, and symptoms alleviating after defecation. The stool may become thin and grooved.

　　4. When the tumor invades the bladder and urethra, symptoms such as frequent urination, urgency, dysuria, and difficulty in urination may occur; when the tumor invades the vagina, it may cause a rectovaginal fistula, with feces flowing out of the vagina; when the tumor invades the sacrum and nerves, severe pain in the sacral tail and perineum may occur; when the tumor compresses the ureter,腰部胀痛 may occur; and the tumor can also compress the external iliac vessels, leading to lower limb edema. All these symptoms indicate that the tumor is in an advanced stage.

　　5. When the tumor spreads to distant organs such as the liver and lungs, the corresponding organs may show symptoms. For example, if it spreads to the lungs, it may cause dry cough and chest pain.

　　6. Patients may experience varying degrees of fatigue, weight loss, and other symptoms.

　　Since the etiology of colorectal cancer is not completely clear, there is still no special preventive method. The preventive measures listed below are mainly to reduce the chance of cancer development and to detect and treat patients early.

　　1. Do not eat too much salty and spicy food, and do not eat overcooked, undercooked, expired, or spoiled food; for the elderly, the weak, or those with certain genetic predispositions to diseases, eat some cancer-preventive foods and alkaline foods with high alkalinity in moderation to maintain a good mental state.

　　2. Have a good mental attitude towards stress, combine work and rest, and do not overwork. It can be seen that stress is an important cancer trigger. Traditional Chinese medicine believes that stress leads to overwork and physical weakness, thus causing a decrease in immune function, endocrine disorders, internal metabolism disorders, and the deposition of acidic substances in the body; stress can also lead to mental tension, causing qi stasis and blood stasis, internal fire, and so on.

　　3. Strengthen physical exercise, enhance physical fitness, exercise more in the sunshine, and sweat more to excrete acidic substances in the body through sweat, avoiding the formation of an acidic body.

　　4. Live a regular life. People with irregular living habits, such as staying up all night to sing karaoke, play Mahjong, not returning home at night, and so on, will aggravate acidification of the body, making it easy to develop cancer. It is necessary to develop good living habits to maintain an alkaline body and keep various types of cancer diseases away from oneself.

　　5. Do not eat contaminated food, such as contaminated water, crops, poultry and eggs, moldy food, and so on. Eat some green organic food and prevent disease from entering through the mouth.

　　The examinations that rectal cancer patients need to do include pathological examination, cancer embryonic antigen determination, sigmoidoscopy, barium enema contrast examination, B-ultrasound examination, CT scan, MRT examination, defecation contrast examination, and so on.

　　1. Pathological Examination: It is the main basis for the diagnosis of rectal cancer. To avoid misdiagnosis and mismanagement, it is absolutely necessary to obtain the results of pathological examination before or during surgery to guide treatment. Under no circumstances should the anus be easily removed.

　　2. Cancer Embryonic Antigen Determination: A significant decrease in cancer embryonic antigen after surgery or chemotherapy indicates good treatment effect. If the surgery is not thorough or chemotherapy is ineffective, the serum cancer embryonic antigen often remains at a high level. If the cancer embryonic antigen decreases to normal and then rises again after surgery, it often suggests tumor recurrence.

　　3. Sigmoidoscopy Examination: For those who cannot palpate a mass during rectal examination but have suspicious clinical symptoms or cannot rule out tumors, a sigmoidoscopy must be performed further. For rectal cancer, a rigid sigmoidoscopy is generally sufficient, and the gross morphology of the lesion can be directly observed under the scope, and living tissue specimens can be obtained accordingly.

　　4. B-ultrasound Examination: For cases found to have rectal tumors, further rectal cavity B-ultrasound can be performed. Its advantage is that it can judge the infiltration depth and scope of rectal cancer, and also has certain value for whether the lymph nodes have metastasized.

　　5. Defecation Contrast Examination: When rectal cancer is accompanied by constipation symptoms, a defecation contrast examination should be performed. It can show intestinal wall stiffness, defects, mucosal damage, perineal descent, and anterior rectal bulging.

　　What kind of food is good for rectal cancer patients to eat

　　Patients with rectal cancer should have a diverse diet, avoid being picky, and not consume high-fat and high-protein diets for a long time. They should often eat fresh vegetables rich in vitamins and cancer-preventing foods, such as tomatoes, deep green and cruciferous vegetables (celery, coriander, kale, rapeseed, radish, etc.), soy products, citrus fruits, malt and wheat flakes, scallions, garlic, ginger, yogurt, and so on.

　　What foods should rectal cancer patients avoid eating

　　Rectal cancer patients should avoid smoking and eating smoked food, fried food, overly spicy food, and food that is too strong in stimulation and difficult to digest. The more animal fat intake from the diet, the greater the risk of dissolving and absorbing carcinogens. A high-fat diet can increase the secretion of bile acids in the intestines, which has potential stimulation and damage to the intestinal mucosa. If exposed to this kind of stimulation and damage for a long time, it may induce the production of tumor cells, leading to colorectal cancer.

　　Eat less or not eat foods rich in saturated fat and cholesterol. Including: lard, beef fat, chicken fat, mutton fat, fatty meat, animal internal organs, fish roe, squid, cuttlefish, egg yolks, and palm oil and coconut oil, etc.

　　The most common treatment for rectal cancer in Western medicine is surgery, and the type of surgery is determined according to the location of the tumor in the rectum. There are two systems in the rectal wall, namely the submucosal lymphatic plexus and the intermuscular lymphatic plexus. The metastasis of cancer cells in the lymphatic system of the intestinal wall is rare. Once the cancer cells penetrate the intestinal wall, they will spread to the external lymphatic system of the intestinal wall.

　　Generally, the first to be affected is the para-aortic lymph nodes at the same level or slightly higher than the tumor, then gradually upward to the intermediate lymph node groups accompanying the superior hemorrhoidal artery, and finally to the para-colic artery lymph node group. The upward lymphatic metastasis mentioned above is the most common metastasis method of rectal cancer.

　　If the tumor is located below the rectum, cancer cells can also horizontally infiltrate the obturator lymph nodes along the lymphatic vessels of the levator ani muscle and the pelvic fascia, or flow to the internal iliac lymph nodes along the hemorrhoidal artery. Sometimes cancer cells can also pass downward through the levator ani muscle, drain to the ischiorectal fossa lymph nodes and inguinal lymph nodes along the hemorrhoidal artery, as the lymphatic metastasis direction of rectal cancer above the rectum is almost always upward, the removal of the lymphatic tissue adjacent to the tumor and above this level can achieve the purpose of radical surgery, and there is a possibility of preserving the anal sphincter muscle.

　　The lymphatic metastasis of rectal cancer below the rectum is mainly upward, but there is also a possibility of horizontal metastasis to the internal iliac lymph nodes and obturator lymph nodes. Radical surgery needs to include the surrounding tissues of the rectum and anal canal and the levator ani muscle, so the anal sphincter muscle cannot be preserved.