Rectal cancer is formed by the malignant transformation of rectal tissue cells. With the improvement of quality of life, the incidence of rectal cancer is increasing year by year, and it has been reported that the incidence of colorectal cancer (colon cancer + rectal cancer) ranks third (the first two are lung cancer and gastric cancer), and by 2015 the incidence of colorectal cancer may exceed that of lung cancer and gastric cancer and rank first. Therefore, research on the diagnosis and treatment of rectal cancer is a very important topic.
Causes
The cause of rectal cancer is still not clear, and its incidence is related to social environment, dietary habits and genetic factors. Rectal polyps are also a high risk factor for rectal cancer. It is basically accepted that high intake of animal fat and protein and insufficient intake of dietary fiber are the high risk factors for the development of rectal cancer.
Disease stage
Stage 0: cancer is limited to the mucosal layer, without lymph node metastasis
Stage I: tumor is confined to the intrinsic muscular layer without lymph node metastasis
Stage II: tumor infiltration beyond the intrinsic muscular layer, but no lymph node metastasis
Stage III: metastasis in lymph nodes
Stage IV: distant metastasis (liver, lung, etc.) or peritoneal metastasis
Clinical manifestations
Early stage rectal cancer is mostly asymptomatic
Patients with progressive cancer (middle and late stage) show symptoms such as abdominal pain, blood in stool, thinning of stool and diarrhea
1. When rectal cancer grows to a certain extent, blood in stool can appear. A small amount of bleeding is not easily detected by the naked eye, but a large number of red blood cells can be found when the stool is examined by microscope, and the so-called fecal occult blood test is positive. When there is a large amount of bleeding, it can appear as blood in the stool with bright red or dark red color. When the cancer surface breaks down and forms ulcers and the tumor tissue is necrotic and infected, pus and blood, mucus and blood stools may appear.
2.Patients may have different degrees of incomplete stool feeling, anal drop feeling and sometimes diarrhea.
3.When rectal tumor causes narrowing of intestinal lumen, symptoms of intestinal obstruction (abdominal pain, abdominal distension, difficulty in defecation) may appear in different degrees. The stool can be thin and with grooves.
4.When tumor invades bladder and urethra, frequent, urgent, painful urination and difficulty in urination may appear; when tumor invades vagina, rectovaginal fistula and fecal fluid may appear; when tumor invades sacrum and nerves, severe pain in sacrococcygeal area and perineum may appear; when tumor invades and presses ureter, swelling and pain in lumbar area may appear; when tumor also presses external iliac vessels, edema of lower limbs may appear. All the above symptoms indicate that the tumor is in advanced stage.
5.When the tumor metastasizes distantly (liver, lung, etc.), the corresponding organs can show symptoms. For example, dry cough and chest pain may appear when metastasis to lung.
6.Patients may have different degrees of weakness, weight loss and other symptoms.
For patients with the above symptoms (abdominal pain, blood in stool, thinning of stool and diarrhea), it is recommended to go to regular anorectal clinics of hospitals and not to attribute the above symptoms to hemorrhoids. Many patients have delayed treatment because of treating rectal cancer as hemorrhoids.
Diagnosis and identification of auxiliary examination
1.Fecal routine + occult blood: it can be used as a simple screening index, if occult blood is positive, further examination is needed to understand the condition of gastrointestinal tract (stomach, small intestine, large intestine and rectum).
2.Tumor marker examination: there are two main markers for colorectal cancer: CEA and CA-199, which should be noted for liver and lung metastasis if they are elevated before surgery, and the positive rate of CEA is about 30% before surgery and about 70% after surgery for recurrence.
3. Patients who have no problems with rectal examination should not let down their guard: further colonoscopy is feasible to understand the situation of the rectum and large intestine that cannot be reached by finger diagnosis. If you do not want to perform colonoscopy, barium enema is feasible (note that before performing colonoscopy or barium enema, you must exclude the presence of intestinal obstruction, such as intestinal obstruction is prohibited to take laxatives to prepare the intestine).
4, chest X-ray or chest X-ray: exclude the presence of lung metastases
5.Liver ultrasound or abdominal CT examination: exclude the presence of liver metastases
6.Pelvic CT or magnetic resonance imaging (MRI) examination: to understand the infiltration of tumor and the presence of pelvic lymph node metastasis
7.Anal stool control function test: this test is needed to understand the anal stool control function before internal sphincter resection surgery.