Rectal cancer is one of the common malignant tumors in the gastrointestinal tract, ranking second after gastric cancer, with more men than women. Rectal cancer is mostly seen as glandular tumor, the surface of the mass is not smooth and uneven, the texture is hard, and the location of rectal cancer is generally low, so the surgery is not easy to complete and the recurrence rate is high after surgery. Rectal cancer is mostly caused by diet, inflammatory bowel disease, adenoma carcinoma, etc., so that blood is the most common.
I. Causes of rectal cancer
1.Diet: Experts believe that high fat, high protein and low fiber are related to the occurrence of rectal cancer. The possible reason is that high-fat and high-protein food can increase methylcholanthrene in stool, which can cause increased secretion of bile acid and be decomposed into unsaturated polyunsaturated hydrocarbons by anaerobic bacteria in the intestine, both of which are carcinogenic substances; reduced amount of fiber slows down the speed of stool passing through the intestine, which increases the contact time between these carcinogenic substances and intestinal conjunctiva and leads to increased chances of carcinogenesis.
2.Inflammatory bowel disease: ulcerative colitis and clonorchisis due to destruction of intestinal mucosa, ulcer repair and proliferation, and carcinogenesis in the process of granulation tissue formation. Schistosomiasis eggs deposited in the rectal mucosa and chronic inflammatory stimulation can lead to the occurrence of rectal cancer.
Adenoma carcinoma: adenomatous polyps can become cancerous and are considered one of the causes of rectal cancer. Adenoma can be divided into three types: tubular adenoma, villous adenoma and mixed adenoma. Tubular adenomas have a high incidence, and villous adenomas have a high cancer rate. There are hereditary familial adenomas, which are regarded as precancerous lesions.
4.Other: such as immune function defects, genetic factors, viral infections, postoperative effects of gastric and cholecystectomy, etc., also play a role in the occurrence of rectal cancer.
Clinical manifestations of rectal cancer: early stage of rectal cancer can be asymptomatic, and as the cancer lesion gradually increases, a series of symptoms can be produced.
1.Intestinal stenosis and obstruction: the cancer infiltrates around the circumference of the intestinal wall, narrowing the intestinal cavity, especially at the junction of rectum and sigmoid colon, which is mostly hard cancer of stenosis and is very likely to cause obstruction. Recto-pot belly cancer, because it is mostly ulcerated and the recto-pot belly is wider, is estimated to cause narrow obstruction only in about 1 to 2 years, with thin stool formation, difficult defecation and constipation, causing abdominal discomfort, gas and pain. Due to the accumulation of feces, in the upper part of the obstructed sigmoid colon area, sometimes in the left lower abdomen, can be found in the ligamentous mass.
2.Blood in stool: it is the most common symptom of rectal cancer, but it is often ignored by patients. Blood in stool is mostly red or dark red, mixed with mucus and blood of stool or pus and blood, sometimes accompanied by blood clots and necrotic tissue. The above symptoms are caused by the obstruction of blood transport after the proliferation of cancer, necrosis and erosion of tissues, ulceration and infection, and the consequence of ulcer formation.
3.Other: If rectal cancer infiltrates other organs and tissues in late stage, it may cause symptoms of lesions there. Invasion of sacral plexus may cause pain in sacrum and perineum, similar to sciatic nerve pain; invasion of bladder and prostate may cause cystitis, urethritis, vesico-rectal fistula, urethro-rectal fistula, vaginal rectal fistula in women, and discharge of feces and mucus pus and blood from vagina. Liver metastasis may cause hepatomegaly, jaundice, ascites and other symptoms, and systemic symptoms may include anemia and other cachexia, and sometimes acute intestinal obstruction, lower gastrointestinal hemorrhage and perforation may cause diffuse peritonitis and other symptoms.
4, the ambassador habit change: because of the mass and its secretions, can produce intestinal irritation symptoms, frequent bowel movements, defecation is not day feeling, shortness of breath and other symptoms, but the discharge is mostly mucus pus blood-like material, initially these “pseudo-diarrhea” phenomenon occurs in the early morning shortly after waking up, called morning diarrhea. Later, the number of times gradually increased, and even at night can not sleep, changing the old stool habits.
5.Anal pain and anal incontinence: Lower rectal cancer may cause local pain if it infiltrates the anal canal; if it involves the anal sphincter, it may cause anal incontinence, and pus and blood stool often flows out and pollutes the underwear; cancer infection or metastasis may cause lymph node enlargement in the groin.
III. Diagnosis of rectal cancer.
In general, patients with bleeding stool should be highly alert clinically and should not be rashly diagnosed as “dysentery”, “internal hemorrhoids”, etc. Further examination is necessary to exclude the possibility of cancer. For the early diagnosis of rectal cancer, we must pay attention to the application of rectal finger examination, proctoscopy or sigmoidoscopy and other examination methods.
1.rectal finger examination: about 90% of rectal cancer, especially lower rectal cancer, can be detected by finger examination alone. This diagnostic method is simple and feasible, and the size and degree of infiltration of the lump, whether it is fixed or not, and whether there are implanted lumps outside the intestinal wall or in the pelvic cavity can also be determined through rectal finger examination.
2.Proctoscopy or sigmoidoscopy: After rectal finger examination, proctoscopy should be performed to assist diagnosis under direct vision, to observe the shape, upper and lower edges and distance from the anal edge of the mass, and to take tissue of the mass for pathological section to determine the nature of the mass and its differentiation degree. If the cancer is located in the middle or upper rectum and cannot be reached by fingers, sigmoidoscopy is a better method.
With the changes in life and people’s habits, the incidence of rectal cancer is increasing and getting younger. Therefore, it is important to develop good living habits to prevent rectal cancer, eat healthy diet, eat less junk food, try to exercise and improve their immune function to stay away from rectal cancer.
IV. Clinical manifestations of rectal cancer
(a) Change in bowel habit, bloody stool, pus-blood stool, urgency, constipation, diarrhea, etc.
(2) Gradual thinning of stool, and in the late stage, there is obstruction of defecation, wasting and even malignancy
(c) Rectal finger examination: it is a necessary examination step for the diagnosis of rectal cancer, about 80% of rectal cancer patients can be found through natural rectal finger examination, and hard and uneven masses can be palpated; in advanced stage, narrow intestinal lumen masses can be palpated and fixed finger sleeve can see dirty pus and blood containing feces
(d) Rectoscopy: the size and shape of the tumor can be seen and the tissue can be taken directly for pathological examination.