How to diagnose early stage colorectal cancer

As people's health awareness increases, many middle-aged and elderly people will regularly undergo routine physical examinations including blood tests, abdominal B-ultrasound, chest X-rays, etc., but few people will take the initiative to do intestinal health checks. The symptoms of early colorectal cancer are relatively hidden. In the early stages of the disease, or even in the late stages of the disease, patients may not have obvious local symptoms, so that many patients are already in the middle and late stages when they are diagnosed, and the treatment effect is greatly reduced. Therefore, intestinal health checks are particularly important.

However, early colorectal cancer has no specific symptoms. How can we detect colorectal cancer early through physical examination?

Digital rectal examination

Doctors can judge anorectal diseases through the simplest and most direct palpation and observation. More than half of colorectal cancers occur in the rectum, and 80% of rectal cancers are in the middle and low positions. Rectal and anal digital examination can detect and make preliminary judgments on perianal diseases and colorectal cancer.

The rectum of an adult is generally 15 cm long. The rectal wall 7-8 cm below the anus can be directly palpated by hand, and slightly raised nodules can be found on the rectal mucosa. More than half of the colorectal cancer patients in China have rectal cancer, and among the rectal cancer patients, about 60 to 70 percent have low-mid rectal cancer. In other words, 70% of rectal cancer (about one-third of colorectal cancer) can be found through rectal digital examination. If the doctor finds mucus on the finger cot during the examination, it means that the patient has purulent and bloody secretions in the rectum. If it is stained with dark red blood, it may indicate intestinal bleeding, and bright red may be hemorrhoidal bleeding. Most rectal cancers, especially low-mid rectal cancers, can be found through rectal digital examination. In addition, the shape, texture and mobility of the tumor can also be determined through rectal digital examination.

Fecal occult blood test

Fecal occult blood test is of great value in the diagnosis of gastrointestinal bleeding and is often used as a screening indicator for the early diagnosis of gastrointestinal malignancies.

Why do we need to do occult blood test to screen for colorectal cancer: When there is a small amount of bleeding in the digestive tract, there will generally be no symptoms such as blood in the stool or black stool. The appearance of the stool is normal to the naked eye, but the fecal occult blood test can be used to judge the very small amount of bleeding in the digestive tract. In fact, not only colorectal cancer, but also digestive tract tumors such as gastric cancer, in the early stage of tumor occurrence, the tumor will erode the mucosa and submucosal blood vessels, causing very small amounts of digestive tract bleeding. This very small amount of bleeding is difficult to judge with the naked eye. At this time, a stool examination can be performed to find out whether there is hidden digestive tract bleeding. For people who have no history of gastric disease, if the physical examination finds that the fecal occult blood test is positive, it is recommended to do it again at an appropriate time. If it is still or continues to be positive, then you need to be vigilant. First of all, digestive tumors should be ruled out. The most common sites of digestive tract tumors are the stomach, colon, and duodenum. Further colonoscopy or gastroscopy should be performed under the advice of a specialist. (Appendix: Positive fecal occult blood test: intermittently positive in case of digestive tract ulcer bleeding; and often persistently positive in case of digestive tract tumors, so it can be used as a way to distinguish between benign and malignant bleeding.)