It is true that colorectal cancer may have certain symptoms, but not all people with these symptoms have colorectal cancer, and most of them do not. I often have to go back and forth with my patients in the clinic for this matter, and sometimes I think, “Why don’t we just do a colonoscopy for him, rather than bargaining here? We often read reports or interviews in the medical section that we should be alert to the presence of colorectal cancer if there are bloody stools, changes in bowel habits, or accompanying weight changes. But are these symptoms useful or not? First of all, we must clarify a few points with you: 1. Early stage colorectal cancer is almost asymptomatic. In order to have symptoms of colorectal cancer, it is basically necessary to reach stage 2 or even stage 3 or above. 2. Age is the important factor affecting the incidence of bowel cancer. Change in bowel habit is not unique to colorectal cancer, it is also a very common symptom of functional gastrointestinal disease. For example, as long as the speed of intestinal peristalsis becomes faster, the water is not fully absorbed, and the stool is still thin and soft at the anal opening, it may become thin; while if the peristalsis is slower and the water is absorbed, the stool will be harder or cause constipation. Therefore, it is very difficult to tell if you have colorectal cancer just by whether your bowel habits have changed, and it will add to your fear and distress. Because colorectal cancer is an age-related disease, and with each passing year, young people with similar symptoms are often functional gastrointestinal diseases, and it is difficult to predict the presence of colorectal cancer based on symptoms alone, compared to adults over 50 years old. If you have had colonoscopy in recent years, based on the fact that it takes five years or more for adenoma to grow into cancer, and the chance of cancer causing symptoms is relatively small, you do not need to receive colonoscopy repeatedly, even if you have done it, it will not help the symptoms, but will worsen the symptoms because of worry or tension (because anxiety is an important cause of functional gastrointestinal disease symptoms), and you should You should receive medication to control functional gastrointestinal disorders or adjust your daily routine. Generally, only progressive adenomas found by colonoscopy should be followed up by colonoscopy within a short period of time, and even then only after three years, so there is no need to undergo annual colonoscopy. As for normal or small adenomas, it is generally recommended to follow up with colonoscopy after five years. The water in the stool will be gradually absorbed by the intestinal mucosa as it peristalsis in the large intestine, so that the stool will gradually become dry and hard as it moves from the proximal colon to the anus, therefore, symptoms such as change in bowel habits or bloody stool are more likely to occur in remote colon cancer or rectal cancer, while the stool in the proximal colon is still in liquid form or soft stool, which usually does not easily cause friction with the tumor. In the proximal colon, because the stool is still liquid or soft, it is usually less likely to rub against the tumor and cause the above symptoms. On the contrary, because it is not easy to have symptoms, tumors that occur in the proximal colon often grow to a considerable size before they are diagnosed, and are often not diagnosed until anemia occurs and hemoglobin drops to a certain level and then symptoms such as wheezing, dizziness or pallor begin to appear in the doctor. 5. People with hemorrhoids may also have rectal cancer Some people have hemorrhoids, so they discharge bloody stools and wishfully believe that it is due to hemorrhoids. If you’ve never had a screening test, it’s a good idea to be vigilant. No one says that people with hemorrhoids are immune to rectal cancer, and ostriches selectively assume that the cause of bleeding must be hemorrhoids, and with one thought, life may go in a completely different direction. Many people who are screened for early-stage cancer exclaim, “How could this happen? I was fine, right? As we can see, the most common symptom of colorectal cancer is called “asymptomatic”, and when there are really symptoms, the disease has already progressed to a certain level. What should we do then? It is good to be alert with symptoms, but more important is age. Over 50 years old, screening test is the key action for early diagnosis even if there are no symptoms. It’s not called a screening test until you have symptoms, it’s called a medical visit.