Colorectal cancer includes colon cancer and rectal cancer. It has become a highly prevalent tumor in China, seriously threatening the health of the nation. According to the data from the National Cancer Center in February this year, it ranks among the top four tumor incidence rates for both men and women. About 90% of intestinal cancers are evolved from intestinal polyps, which evolve from adenomatous polyps to cancer, generally takes 5-10 years, thus, to detect and remove at the stage of polyps is an effective way to prevent intestinal cancers, and the best examination to detect intestinal polyps is colonoscopy. Therefore, when you visit a gastroenterologist, your doctor will often recommend you to have a colonoscopy. This is especially true for people over the age of 40 and those with intestinal symptoms. In the United States, colorectal cancer is one of the highly prevalent cancers and the number two cancer killer. In China, the incidence of colorectal cancer has caught up with the rising standard of living. Each person is at different risk, and on average, about one in twenty Americans may develop colorectal cancer. If someone in the immediate family has rectal cancer, the risk increases two to three times. Ninety percent of colorectal cancers are seen in people over the age of 50. In recent years, the incidence has increased in younger people. Early symptoms of colorectal cancer are neither obvious nor typical, and can be easily missed. Early symptoms include blood in stool, black stool, change in bowel habits (sudden constipation or diarrhea, increased frequency, incomplete defecation, etc.), change in stool characteristics (thinning and deformation, etc.), abdominal distension and pain, unexplained anemia or weight loss, etc. Risk factors for colorectal cancer include obesity, smoking, excessive alcohol consumption, excessive intake of red meat and processed meat products, lack of physical activity, family history, genetic factors and other intestinal diseases. The prevention of colorectal cancer includes weight control, smoking cessation, diet adjustment, meat reduction, high fiber food intake, regular exercise and good mood, etc. So, how does colorectal cancer occur? The exact cause of colorectal cancer is still unclear, but most colorectal cancers are just a small polyp at the earliest and usually do not cause any symptoms. A polyp is a neoplastic tissue growth, and there are many kinds, some of which do not develop into cancer (which can be collectively referred to as benign polyps) and some of which can develop into cancer (which can be collectively referred to as precancerous polyps). Starting with precancerous polyps, they undergo some genetic mutations, develop into atypical hyperplasia, and then often take years or even a decade to develop into cancer. Patients with family history will develop faster. Progression from early stage cancer to advanced stage again takes some time, and the rate of progression often depends on the malignancy of the cancer. About 15% of women and 25% of men over the age of 50 have these precancerous polyps. The purpose of screening is to detect these precancerous lesions and relatively small early cancers and intervene in a timely manner. Although colorectal cancer remains one of the most prevalent cancers, it is also one of the most preventable cancers. This is crucial. If detected early and treated promptly, colorectal cancer can be cured very well. The incidence of colorectal cancer in the United States has been on a downward trend over the past two or three decades, at least in part due to the spread of various screening tools. From 2000 to 2010, colonoscopy screening rates rose from 19% to 55% among people aged 50 to 75 years in the United States, and the incidence of colorectal cancer fell by 30% over the same period. In China, colorectal cancer has also become a highly prevalent cancer, and most of them are already in the middle and late stages when detected. What is more frightening is that the trend of colorectal cancer in China is very young. The average age of onset of colon cancer in China is 48.3 years old, which is 20 years younger than the average age of onset of colon cancer in the United States (69.8 years old). Therefore, early detection and treatment are especially important. There are several screening methods for colorectal cancer recommended by the American Cancer Society and the FDA. Colonoscopy is probably the most direct and effective means among them. Not only can colonoscopy directly examine the intestines, but it can also remove suspicious lesions. What does a colonoscopy look like? Preparation: The day before the test, the patient should eat only liquid food and drink a laxative prescribed by the doctor to cleanse the intestines. This is important so that the doctor can see clearly during the examination and detect any small lesions. Colonoscopy: Simply put, a colonoscope is a thin, flexible, lighted tube with a small lens at the end. The doctor puts it into the patient’s intestines to check for polyps or other abnormal changes. If so, a small device at the front of the colonoscope will cut out the diseased tissue. The entire procedure usually takes less than half an hour. The excised tissue is sent to a pathologist for microscopic examination. Although the colonoscopist will make a general judgment based on the shape of the lesions, it is up to the pathologist to confirm whether the lesions are benign or malignant. Is it painful to have a colonoscopy? Many hospitals now offer “painless colonoscopy”. Before the procedure, the patient is usually sedated by a gastroenterology endoscopist, and if necessary, an anesthesiologist is called in to provide anesthesia. Therefore, 99% of patients can easily complete the colonoscopy. The vast majority of patients either drift off to sleep or wake up without any recollection of having such a test. Painless colonoscopy is also performed in many hospitals in China. Usually secondary hospitals are equipped with endoscopy centers. Does a colonoscopy hurt without anesthetic? Generally, people still feel pain, and the degree varies from person to person. According to the descriptions of those who have done it, the lighter the pain is like diarrhea, the heavier the pain. All in all, it is a very unpleasant experience. But a painless exam is much less painful or completely painless. You sleep and the test is over. Are there any risks associated with having a colonoscopy? Only specially trained doctors are allowed to perform colonoscopies. Although colonoscopy was invented by surgeons, today, in most cases, it is done by gastroenterologists. No operation can be absolutely risk-free, but colonoscopy is relatively safe. The chance of causing intestinal perforation is less than 1 in 1000 and the chance of bleeding is less than 1%. Therefore, colonoscopy is an effective and feasible screening method for colorectal cancer. The American Cancer Society recommends that people at average risk, starting at age 50, have one every 10 years. If the risk is higher than average, it is recommended to start screening earlier, discussing the details with your doctor. What are other screening methods besides colonoscopy to prevent colon cancer? CT Colonography: CT imaging is done every five years. Patients also need to clean out their intestines, but do not need sedation or anesthesia. Very small lesions may not be visible due to resolution limitations. If abnormalities are found a colonoscopy is still needed. Rectoscopy (Flexible Sigmoidoscopy) and sigmoidoscopy: Similar to colonoscopy, but only examines the rectum and part of the colon. It is done once every five years. Patients need a simple bowel cleanse and most of the time do not need sedation or anesthesia. Like proctoscopy, it can only diagnose the lower part of the large intestine and does not help with higher lesions. 3. Guaiac-based Fecal Occult Blood Test (gFOBT) and Fecal Immunochemical Test (FIT): Both are based on blood in the stool. Patients do not need to have their bowels cleaned out or be anesthetized, and the stool is left and sent for testing according to the procedure. The test is done once a year, and if the test result is positive, a colonoscopy is required. 4. Stool DNA test: To detect DNA changes in stool that may be related to precancerous lesions or cancer, and to detect blood in stool. It is done once every one to three years. If the test result is positive, a colonoscopy is required. 5.Capsule endoscopy: Preparation before capsule endoscopy is similar to colonoscopy, it is one of the best means to diagnose gastrointestinal diseases with single-use, no chance of cross-infection such as hepatitis and AIDS, painless, non-invasive and no risk of perforation. The disadvantage is that biopsy cannot be taken. 6.Tumor marker test: It can only be used as an auxiliary means. Conclusion Colorectal cancer is one of the highly prevalent cancers, but it is also preventable, controllable and curable . In addition to weight control, smoking cessation, diet adjustment, regular exercise and good mood, early screening is crucial for people of appropriate age. There is more than one screening method, but colonoscopy is the most direct and effective. The time to start screening and the specific screening method will vary from person to person, so we recommend discussing with your doctor.