Colorectal cancer is a common malignant tumor, including colon cancer and rectal cancer. The incidence rate of colorectal cancer is from high to low: rectum, sigmoid colon, cecum, ascending colon, descending colon and transverse colon, and in recent years, there is a tendency to develop to the proximal end (right hemicolectomy). Its development is closely related to lifestyle, genetics and colorectal adenoma.
Common causes
It is associated with high fat and low fiber diet, chronic inflammation of the large intestine, colorectal adenoma, genetic factors and other factors such as schistosomiasis, pelvic radiation, environmental factors (e.g. molybdenum deficiency in soil), and smoking.
Etiology
The occurrence of colorectal cancer is related to high fat and low fiber diet, chronic inflammation of the colon, colorectal adenoma, genetic factors and other factors such as schistosomiasis, pelvic radiation, environmental factors (e.g. molybdenum deficiency in the soil), and smoking.
Clinical manifestations
Colorectal cancer has no symptoms in early stage, or the symptoms are not obvious, only feeling discomfort, indigestion and occult blood in stool. With the development of cancer, symptoms will gradually appear, which are manifested as change of stool habit, abdominal pain, blood in stool, abdominal mass, intestinal obstruction, etc., with or without systemic symptoms such as anemia, fever and emaciation. Tumor may cause changes in affected organs due to metastasis and infiltration. Colorectal cancer shows different clinical symptoms and signs due to different parts of its development.
1.Right hemi-colon cancer
The main clinical symptoms of right hemicolectomy are loss of appetite, nausea, vomiting, anemia, fatigue and abdominal pain. Right hemicolectomy leads to iron deficiency anemia, which shows fatigue, weakness, shortness of breath and other symptoms. Because of the wide intestinal cavity, abdominal symptoms will appear only when the tumor grows to a certain volume, which is one of the main reasons for the late stage when the tumor is diagnosed.
2.Left colon cancer
The lumen of left hemicolectomy is narrower than the lumen of right hemicolectomy, so left hemicolectomy is more likely to cause complete or partial intestinal obstruction. Intestinal obstruction leads to change of stool habit, constipation, blood in stool, diarrhea, abdominal pain, abdominal cramps and bloating. Fresh bleeding stools indicate that the tumor is located in the left hemicolectomy or rectum. The diagnosis of the disease stage is often earlier than that of right hemicolectomy.
3.Rectal cancer
The main clinical symptoms of rectal cancer are blood in stool, change of bowel habit and obstruction. If the cancer site is low and the fecal mass is hard, the bleeding is easily caused by the friction of the fecal mass, mostly bright red or dark red, not mixed with formed feces or attached to the surface of the fecal column, which is misdiagnosed as “hemorrhoid” bleeding. The secondary infection caused by lesion stimulation and mass ulceration constantly causes defecation reflex, which is easily misdiagnosed as “enteritis” or “bacillary dysentery”. If the cancer grows in a circular pattern, it leads to narrowing of intestinal lumen, which is manifested as deformation and thinning of fecal column in early stage and incomplete obstruction in late stage.
4.Tumor infiltration and metastasis
The most common form of infiltration of colorectal cancer is local invasion, and the tumor invades the surrounding tissues or organs, causing the corresponding clinical symptoms. Anal incontinence, persistent pain in lower abdomen and lumbosacral region are caused by rectal cancer invading sacral plexus. Tumor cell implantation and metastasis to the abdominopelvic cavity form corresponding symptoms and signs. Rectal finger examination can find masses in the cysto-rectal fossa or utero-rectal fossa, and tumor implantation and metastasis in the abdominopelvic cavity extensively form peritoneal effusion. There are two main ways of distant metastasis of colorectal cancer: lymphatic metastasis and hematogenous metastasis. Tumor cells metastasize to lymph nodes through lymphatic vessels, and also to liver, lung, bone and other parts through bloodstream metastasis.
Examination
1.Laboratory examination
Laboratory tests such as routine blood, complete biochemistry (liver and kidney function + serum iron), routine stool + fecal occult blood, etc. can help to understand whether the patient has iron deficiency anemia, liver and kidney function and other basic conditions. Blood tumor marker carcinoembryonic antigen (CEA) test is performed to help the diagnosis of tumor. In patients with colorectal cancer, high CEA level does not mean that all of them have distant metastasis; there are a few patients with metastases, CEA is not increased.
2.Endoscopy
Colonoscopy is to extend a fiberoptic colonoscope into the ileocecal region at the beginning of the colon to examine the colon and rectal cavity, and to perform biopsy and treatment during the examination. Colonoscopy is more accurate than barium enema X-rays, especially for small colon polyps, which are removed by colonoscopy and confirmed pathologically. Removal of benign polyps can prevent their transformation into colorectal cancer, and cancerous polyps can help clarify the diagnosis and treatment.
3.Biopsy and exfoliative cytology examination
Biopsy is of decisive significance to confirm the diagnosis of colorectal cancer, especially early stage cancer and polyp cancer, and to make differential diagnosis of lesions, which can clarify the nature, histological type and malignancy of the tumor, determine the prognosis and guide clinical treatment. The accuracy of abscission cytology examination is high, and it is not easy to obtain satisfactory specimens, so it is rarely used in clinical practice.
Treatment
1.Surgical treatment
(1) The treatment plan for colon cancer is a comprehensive treatment plan mainly based on surgical resection. stage I, II and III patients often adopt radical resection + regional lymph node dissection, and the scope of radical resection and its surgical method are determined according to the location of cancer. stage IV patients with intestinal obstruction and severe intestinal bleeding do not undergo radical surgery for the time being, and palliative resection is feasible to relieve symptoms and improve patients’ quality of life.
(2) The basis of radical treatment of rectal cancer is surgery. Rectal surgery is more difficult than colon surgery. Common surgical methods include: transanal resection (very early stage near the anal verge), total rectal mesenteric resection, low anterior resection, and combined transabdominal anal sphincter abdominal perineal resection. For stage II and III rectal cancer, it is recommended to carry out radiotherapy and chemotherapy before surgery to shrink the tumor and reduce the local tumor stage, and then carry out radical surgery.
2.Comprehensive treatment
(1)Adjuvant chemotherapy? Oxaliplatin combined with fluorouracil (5-fluorouracil) is the standard treatment for patients with stage III colorectal cancer and some colorectal cancer with high-risk factors. It is indicated for patients with rectal cancer who have not received neoadjuvant radiation therapy before surgery and who require adjuvant radiation therapy after surgery.
(2) Treatment of IV colorectal cancer? It is mainly a chemotherapy-based comprehensive treatment program, and chemotherapy drugs include 5-fluorouracil, capecitabine, oxaliplatin, irinotecan, bevacizumab, cetuximab, panitumumab and other drugs, and the commonly used chemotherapy regimens are: FOLFOX, XELOX, FOLFIRI, etc., combined with targeted drug therapy (bevacizumab, cetuximab, panitumumab) on the basis of chemotherapy as appropriate. .