The early symptoms of colorectal cancer are not obvious. They are often ignored or misdiagnosed, which leads to the delay of colorectal cancer to the middle and late stages, which has an impact on the treatment. One of the early symptoms of colorectal cancer is nausea.

Early symptoms of colorectal cancer can appear fullness after eating, accompanied by mild nausea. Tumors in the cardia can begin to suffer from eating disorders, and gradually develop into dysphagia and food reflux. Antral cancer develops further, and vomiting may occur due to pyloric obstruction. In addition, there are the following points:

　　Bloating, abdominal pain. The reason is due to intestinal dysfunction or intestinal obstruction. Most of the parts are concentrated in the middle and lower abdomen, most of them are hidden pain or bloating pain, and there is a tendency to gradually increase.

　　Bleeding blood, because the lesion is closer to the anus, the blood color is mostly bright red or dark red, and often bloody stool is separated. Only when there is a lot of bleeding, the stool is brownish red and jam-like. The right colon cancer patients have this kind, and the bloody stools visible to the naked eye account for 36.5％. This also belongs to the early symptoms of colorectal cancer.

　　Anaemia, when chronic chronic blood loss exceeds the compensatory function of the body''s hematopoiesis, patients can have anemia, an early symptom of colorectal cancer. Tumor obstruction, when the tumor grows to a considerable volume, or infiltrate the muscle layer of the intestinal wall, it can cause intestinal stenosis, the intestinal cavity becomes smaller, and the intestinal content is blocked.

　　Change in bowel habits and traits. Rectal cancer patients can increase the number of stools, but there are not many bowel movements every time, and there is no stool at all, but only some mucus and blood are discharged, and there is a feeling of endless bowel movements. Changes in bowel habits, frequency, and constipation or unexplained diarrhea may occur when the large intestine tumor is relatively large and has erosion, ulcers, or infection.

　　If a cancerous tumor protrudes into the rectal cavity, resulting in a relatively narrow intestinal cavity, the excreted stools tend to become thinner and deformed, and may be flattened, and sometimes some bloodshot blood adheres to the deformed stools.