Old Wang just turned 60 this year and is ready to retire and start enjoying his family’s life. He is physically fit, moves freely and speaks clearly. Usually there is nothing wrong with his body, even small illnesses such as colds and fevers are rare, basically no major illnesses in this life, let alone to the hospital. Wang also better smoking, drinking this bite, usually eat is also big fish and meat, basically nothing to avoid, can be said to be “all five poisons”, but never to the hospital physical examination, although Wang’s unit will be organized every year physical examination. Another year of physical examination, the unit organized another physical examination, as always, the old king is not willing to go to the physical examination. But the family believes that the old king is old, do a physical examination to see if there is discomfort, early detection of problems can be early treatment, even if there is no problem can also be a peace of mind. In the family actively persuaded, the old Wang finally participated in the unit organized medical examination. Many things look good on the surface, but in fact, the body is also the same. After this physical examination, it was found that the old Wang’s left lung has a 2.5cm “nodule”, that is, the lung inside a tumor. Wang had a CT examination at the local hospital to clarify the nature of the “nodule”. For economic reasons, he did not choose to have a whole-body PET-CT examination, but only an enhanced CT of the lung, which was diagnosed as “lung cancer”. After the surgery, the pathology indicated that the mass in the lung was “middle differentiated adenocarcinoma” and had metastasis in the lymph nodes of the lung gate. The story does not end here …… about 3 months after the lung cancer surgery, Lao Wang suddenly did not have a bowel movement for several days, gradually developed nausea and abdominal distension, and finally developed severe stomach pain in the form of paroxysmal colic. At this time, Lao Wang went to the emergency room of the local hospital and checked the abdominal CT suggesting: low-level colon obstruction; thickened sigmoid intestinal wall, narrowed intestinal lumen, colon cancer to be discharged. After a series of conservative treatments such as gastric tube and enema, the abdomen was still rising more and more, which led to the referral to Zhongshan Sixth Hospital. After completing relevant examinations, a dissection was performed and a huge sigmoid colon mass was found, which invaded the intestinal wall and caused the spread of the tumor inside the abdominal cavity. The main surgeon performed sigmoid colon resection for Wang. Because of intestinal obstruction, a large amount of feces had accumulated in the intestinal cavity, and the intestinal tube was connected back only after the intestine was cleaned by irrigation during the operation. The postoperative pathology finally indicated intestinal cancer. Combined with the patient’s previous history of lung cancer and the consultation of lung surgery pathology, the hospital finally diagnosed Lao Wang with sigmoid colon cancer combined with lung metastasis. The culprit of lung cancer was found to be intestinal cancer! From this case, we can see that the clinical manifestations of bowel cancer can be very different. Sometimes, the detection of bowel cancer does not start with the discovery of the primary bowel cancer, but with the discovery of secondary metastatic lesions or discomfort in other areas through other means. So how does bowel cancer metastasize? Metastasis pathway of bowel cancer 1.Local infiltration: Colorectal cancer first grows directly into the deep infiltration of bowel wall first, and infiltration into the longitudinal axis of bowel wall occurs later. It is estimated that it takes 1.5~2 years for the cancer to infiltrate the intestinal wall. In colorectal cancer, the scope of infiltration is mainly assessed by the level of tumor infiltration in the deep intestinal layer, and when the tumor breaks through the plasma membrane layer, it can also infiltrate into adjacent organs, such as uterus, bladder, ureter, etc. 2.Lymphatic route: colorectal cancer metastasizes mainly through lymph nodes: colon cancer first reaches the colon wall and paracolonic lymph nodes, then the lymph nodes around mesenteric vessels and the root of mesenteric vessels; upper rectal cancer metastasizes upward along the superior rectal artery, inferior mesenteric artery and lymph nodes around abdominal aorta; lower rectal cancer metastasizes mainly upward and laterally. 3.Bloodborne route: Bloodborne metastasis of colon cancer is mostly seen in liver, followed by lung and bone; rectal cancer invades the vein and metastasizes to liver along portal vein; it can also be metastasized to lung, bone and brain by iliac vein. 4.Plantation: cancer cells shed from colon cancer can be planted and metastasized in the peritoneum, while rectal cancer has less chance to be planted and metastasized in the upper part of rectum. Old Wang’s lung cancer is that the tumor cells of intestinal cancer metastasized to the lung through blood route, which led to the occurrence of lung tumor. As shown below: From Lao Wang’s case, we can see that: 1. Advanced bowel cancer can have no intestinal symptoms, let alone early bowel cancer! This shows how important it is to perform colonoscopy screening! 2. When lung cancer is diagnosed, it is helpful to keep an extra eye to suspect if there is intestinal cancer, even though there are no intestinal related symptoms. It is even more important to pay attention when there are bowel-related symptoms, and this move may avoid missing the diagnosis of bowel cancer, the culprit that leads to lung cancer. A colonoscopy can detect the problem. At the time of lung metastasis, bowel cancer can already be said to be in advanced stage. However, if it was detected early, Lao Wang would not have later developed intestinal obstruction, abdominal dissemination and required two surgeries with stoma.