Does Colon Cancer Always Cause Hidden Blood in Stool?

Occult blood refers to positive occult blood in routine stool tests, but not all colorectal cancer patients will have occult blood in their stool. Some patients with early-stage colorectal cancer may not have positive occult blood in their stool. However, the majority of colorectal cancer patients will have occult blood in their stool. In the early stages of colorectal cancer, when the tumor is located in the submucosa or has not ruptured, patients usually have no obvious symptoms or atypical symptoms such as nausea, bloating, and loss of appetite. As the tumor grows to a certain extent, its clinical manifestations vary depending on its location. For instance, common symptoms of right-sided colon cancer include abdominal pain, changes in bowel habits, abdominal mass, and anemia. Common symptoms of rectal cancer include rectal bleeding and changes in bowel habits. Common symptoms of small intestine cancer include abdominal mass, intestinal obstruction, and abdominal pain in the middle and late stages. Although occult blood in the stool is a main symptom of colorectal cancer, the most common symptoms are changes in bowel habits, such as increased frequency of bowel movements, rectal bleeding, and frequent urges to defecate. Additionally, the tumor may cause consumption and loss of appetite, leading to fatigue and weight loss. Currently, colorectal cancer cannot be completely cured, but with active and standardized treatment, some patients may have a chance of clinical cure. Patients should pay attention to observing their physical symptoms and seek medical attention promptly if they experience recurrent symptoms or worsening of symptoms such as abdominal pain, abdominal mass, intestinal obstruction, rectal bleeding, changes in bowel habits, and changes in stool consistency.