Colorectal cancer is divided into two categories: colon cancer and rectal cancer. Most colon cancer patients are middle-aged or above, with the average age being 45 years old, and about 5% of patients are under 30 years old. Colon cancer patients may have no symptoms in the early stages, but as the disease progresses, a series of cancer symptoms will appear. Clinically, the middle part of the transverse colon is used as the boundary, and the colon is divided into the left colon and the right colon. Due to the different locations of the cancer, the manifestations are different.

Right colon cancer: Because the intestinal cavity is thick and the feces in the intestine is liquid, cancers in this section of the intestine are mostly ulcer-shaped or cauliflower-shaped, and ring-shaped stenosis is rare, so obstruction does not often occur. However, these cancers often rupture, bleed, become infected secondaryly, and are accompanied by toxin absorption. The main clinical manifestations are:

1. Abdominal pain or discomfort, often located in the right lower abdomen, much like an attack of chronic appendicitis. If the tumor is located in the hepatic flexure and the stool is dry and lumpy, colic may also occur, and attention should be paid to distinguishing it from chronic cholecystitis. About 50% of patients suffer from loss of appetite, fullness, belching, nausea and vomiting.

2. Changes in stool. In the early stage, the stool is thin, with pus and blood, and the frequency of defecation increases. This is related to the formation of cancerous ulcers. The amount of bleeding is small and difficult to see with the naked eye, but the occult blood test is often positive. When the tumor size increases and affects the passage of feces, diarrhea and constipation may occur alternately.

3. Abdominal mass. This mass may be the cancer itself, or it may be a mass formed by extraintestinal infiltration and adhesion.

4. Anemia, weight loss or cachexia.

Left colon cancer: Most are invasive and often cause annular stenosis, so the main clinical manifestations are acute and chronic intestinal obstruction. Clinical manifestations:

1. Abdominal cramps are the main manifestations of cancer accompanied by acute intestinal obstruction, and are also accompanied by abdominal distension, hyperperistalsis, constipation and obstructed exhaust. Chronic obstruction manifests as abdominal distension and discomfort, paroxysmal abdominal pain, hyperactive bowel sounds, Constipation, blood and mucus in the stool, and partial intestinal obstruction sometimes last for several months before turning into complete intestinal obstruction.

2. Difficulty defecation. Half of the patients have this symptom. As the disease progresses, constipation becomes more serious. If the cancer is located in a lower position, you may also experience difficulty in defecation and tenesmus.

3. Blood and mucus in the stool. As the stool in the left colon gradually takes shape and blood and mucus do not mix with the stool, blood and mucus are visible in the stool of about 25% of patients.

The early symptoms of colon cancer are mostly mild or inconspicuous, and are often ignored by patients, so the diagnosis is easily missed. Middle-aged patients should be more vigilant and consider the possibility of colon cancer when they have the following symptoms:

① Changes in bowel habits (such as constipation, diarrhea or poor bowel movements), persistent abdominal discomfort, dull pain or bloating have occurred recently;

② The stool becomes thin or contains blood and mucus;

③ Fecal occult blood test continues to be positive;

④Unexplained anemia, fatigue or weight loss, etc.;

⑤ A mass is palpable in the abdomen.

When the above suspicious phenomena occur, in addition to further medical history inquiry and physical examination, X-ray barium enema or fiberoptic colonoscopy should be performed immediately to rule out space-occupying lesions.