What Is Colorectal Cancer?

Colorectal cancer is a common malignant tumor, including colon and rectal cancer. The incidence of colorectal cancer from high to low is the rectum, sigmoid colon, cecum, ascending colon, descending colon, and transverse colon. In recent years, there has been a trend toward the proximal (right half colon). Its incidence is closely related to lifestyle, heredity, and colorectal adenoma. The age of onset is aging, and the male to female ratio is 1.65: 1.

Basic Information

English name

large intestinecancer

Visiting department

Oncology

Multiple groups

Older men

Common causes

Related to chronic inflammation of the large intestine, colorectal adenoma, genetic factors, etc.

Common symptoms

Early or no symptoms, only indigestion, occult blood in stool, etc.

Causes of colorectal cancer

The occurrence of colorectal cancer is related to 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 (such as molybdenum deficiency in the soil), and smoking.

Clinical manifestations of colorectal cancer

Colorectal cancer is asymptomatic in the early stage, or the symptoms are not obvious, only feeling discomfort, indigestion, occult blood in the stool, etc. With the development of cancer, symptoms gradually appear, manifested as changes in stool habits, abdominal pain, blood in the stool, abdominal mass, intestinal obstruction, etc., with or without systemic symptoms such as anemia, fever and weight loss. Tumor metastasis and invasion can cause changes in affected organs. Colorectal cancer shows different clinical symptoms and signs depending on the location of its occurrence.

Right colon cancer

The main clinical symptoms of the right half colon are loss of appetite, nausea, vomiting, anemia, fatigue, and abdominal pain. Right half colon cancer causes iron deficiency anemia, showing symptoms such as fatigue, fatigue, and shortness of breath. Due to the wide bowel cavity in the right hemicolon, abdominal symptoms may occur until the tumor grows to a certain volume. This is also one of the main reasons for the late stage of the tumor when it is diagnosed.

2. Left colon cancer

The intestinal cavity of the left half colon is narrower than that of the right half colon, and the left half colon cancer is more likely to cause complete or partial intestinal obstruction. Intestinal obstruction leads to changes in bowel habits, such as constipation, blood in the stool, diarrhea, abdominal pain, abdominal cramps, and bloating. A stool with fresh bleeding indicates that the tumor is located at the end of the left colon or rectum. The diagnosis is usually earlier than that of right colon cancer.

3. rectal cancer

The main clinical symptoms of rectal cancer are blood in the stool, changes in bowel habits, and obstruction. Those with lower cancer sites and harder stools are susceptible to bleeding caused by friction of the stools. Most of them are bright red or dark red. They are not mixed with the formed stool or attached to the surface of the fecal column. They are misdiagnosed as "hemorrhoid" bleeding. Lesion irritation and secondary infections of mass ulcers continuously cause defecation reflexes and are easily misdiagnosed as "enteritis" or "bacillary dysentery". The cancerous ring grows, which results in narrowing of the intestinal cavity, with early manifestations of deformation and thinning of the fecal column, and late stages of incomplete obstruction.

4. Tumor invasion and metastasis

The most common form of invasion of colorectal cancer is local invasion. Tumors invade surrounding tissues or organs and cause corresponding clinical symptoms. Anal incontinence, persistent pain in the lower abdomen and lumbosacral region are caused by rectal cancer invasion and phrenic nerve plexus. Tumor cells are implanted and transferred to the abdominal cavity and pelvic cavity to form the corresponding symptoms and signs. Digital rectal examination can be performed in the bladder rectum or uterine rectal fossa and masses. Tumors are widely implanted and transferred in the abdominal cavity and pelvic cavity to form peritoneal fluid. There are two main ways of distant metastasis of colorectal cancer: lymphatic metastasis and hematogenous metastasis. Tumor cells metastasize to lymph nodes through the lymphatic vessels, and can also metastasize to the liver, lungs, bones, and other parts through the bloodstream.

Colorectal cancer examination

Laboratory inspection

Blood tests, biochemical items (liver and kidney function + serum iron), stool routine + fecal occult blood and other laboratory tests can help to understand the basic situation of patients such as iron deficiency anemia, liver and kidney function. The blood tumor marker carcinoembryonic antigen (CEA) test can help the diagnosis of tumors. In patients with colorectal cancer, high CEA levels do not indicate distant metastases; there are a few patients with metastatic tumors that do not increase CEA.

2. Endoscopy

Colonoscopy is to extend the fiber colonoscopy to the ileocele at the beginning of the colon, check the colon and rectal intestine, and perform biopsy and treatment during the examination. Colonoscopy is more accurate than barium enema X-rays, especially for small polyps of the colon, which are diagnosed by colonoscopy and pathologically confirmed. Removal of benign polyps can prevent their conversion to colorectal cancer, and cancerous polyps can help clear diagnosis and treatment.

3. Biopsy and Exfoliative Cytology

Biopsy is decisive for the diagnosis of colorectal cancer, especially early stage cancers and polyps, and the differential diagnosis of lesions. It can clarify the nature of tumors, histological types and malignancy, determine prognosis and guide clinical treatment. Exfoliated cytology has high accuracy, tedious material collection, difficult to obtain satisfactory specimens, and few clinical applications.

Colorectal Cancer Treatment

Surgical treatment

(1) The treatment plan for colon cancer is a comprehensive treatment plan based on surgical resection. Patients of stage , and often use radical resection + regional lymph node dissection, and determine the extent of radical resection and the surgical method according to the location of the cancer. If intestinal obstruction or severe intestinal bleeding occurs in patients with stage IV, radical surgery may not be performed for the time being, palliative resection may be performed to relieve symptoms and improve the quality of life of patients.

(2) The basis of radical treatment for rectal cancer is surgery. Rectal surgery is more difficult than colon. Common surgical methods include transanal resection (very early near the anal margin), total mesorectal resection, low anterior resection, and transabdominal anal sphincter abdomen-perineal resection. For stage and rectal cancer, it is recommended to perform radiation and chemotherapy before surgery to reduce the tumor, reduce the local tumor stage, and then perform radical surgery.

2. Comprehensive treatment

(1) Adjuvant chemotherapy oxaliplatin combined with fluorouracil drugs (5-fluorouracil) is the current standard treatment for patients with stage III colorectal cancer and some colorectal cancer with high risk factors. The treatment time is 6 months. It is suitable for patients with rectal cancer who have not received neoadjuvant radiation therapy before surgery and who need adjuvant radiation therapy after surgery.

(2) The treatment of IV colorectal cancer is mainly a comprehensive treatment plan based on chemotherapy. Chemotherapy drugs include 5-fluorouracil, capecitabine, oxaliplatin, irinotecan, bevacizumab, and cetuximab. Various drugs such as monoclonal antibodies, panitumumab, and other commonly used chemotherapy regimens: FOLFOX, XELOX, FOLFIRI, etc., combined with targeted drug therapy (bevacizumab, cetuximab, panitumumab, etc.) based on chemotherapy as appropriate ).

3. Radiotherapy

At present, the effects are better and more researches are comprehensive surgery and radiotherapy, including preoperative radiotherapy, intraoperative radiotherapy, postoperative radiotherapy, "sandwich" radiotherapy, etc., each with its own characteristics. For patients with advanced rectal cancer, those with local tumor invasion, and those with contraindications to surgery, palliative radiotherapy should be applied to relieve symptoms and reduce pain.