Colorectal Cancer Colorectal cancer is a general term for colon cancer and rectal cancer. Colorectal cancer refers to malignant lesions occurring in the mucosal epithelium of the large intestine under the action of various carcinogenic factors, such as environment or heredity, which have a poor prognosis and a high mortality rate. Colorectal cancer is a malignant tumor of colorectal mucosal epithelial origin. It is one of the most common malignant tumors of the digestive tract. Early colorectal cancer is mostly asymptomatic in early stage. As the tumor increases in size and the condition continues to progress, symptoms are revealed. In fact, for patients who have symptoms in clinic, their local lesions are often obvious and serious, and even in advanced stage. What are the early signs of colorectal cancer? Change of stool shape, such as from thick to thin; black or dark red stool, thin stool, mucus; increased frequency of defecation, but not able to defecate; recurrent hemorrhoids that do not heal, unexplained anemia, weight loss; unexplained stomach bloating and pain. Late Colorectal Cancer Once colorectal cancer enters the late stage, more obvious symptoms may appear, but some symptoms are not specific and related to the location of the cancer. Right colon cancer mainly manifests as indigestion, fatigue, loss of appetite, diarrhea, constipation, or constipation and diarrhea alternately, abdominal distension, abdominal pain, abdominal pressure, abdominal mass and progressive anemia. The location of the mass varies with the location of the lesion. Cecal cancer mass is located in the right lower abdomen, ascending colon mass is located in the right side of the abdomen, colonic hepatic flexure mass is located in the right upper abdomen, and transverse colon mass is located near the umbilicus. In addition, there may be fever, emaciation, and complications such as perforation and limited abscess, at this time the lesion has entered the most advanced stage. Due to the narrow intestinal lumen of sigmoid colon and the acute angle with rectum, it is easy to occur stenosis and progressive intestinal obstruction, and most of them have stubborn constipation, or increase the frequency of defecation. Since the obstruction is mostly in the lower part of sigmoid colon, vomiting is mild or absent, while abdominal distension, abdominal pain, bowel sound and its intestinal pattern are obvious. When the cancer ruptures, the feces may be stained with blood or mucus. The proximal bowel of obstruction may form ulcers due to persistent swelling, ischemia and hypoxia, or even cause perforation, and a large amount of blood and abdominal abscess may also occur. Rectal cancer mainly manifests as increased frequency of stools, thin feces with blood or mucus, accompanied by acute and severe pain. As the cancer may invade the sacral plexus nerve, severe pain may occur. If the bladder is involved, frequent urination, painful urination, urgency of urination, blood in urine and other symptoms may appear. If the cancer invades the bladder, vesicorectal fistula can be formed. Rectal cancer can also cause intestinal obstruction. Anal canal cancer mainly manifests as blood in stool and pain. The pain is aggravated during defecation. When the cancer invades anal sphincter, there may be fecal incontinence. Anal canal cancer may metastasize to inguinal lymph nodes, so enlarged and hard lymph nodes can be touched in the groin.