Like many other types of cancer, colorectal cancer may not have obvious symptoms in the early stages of the disease. This is why cancer screening procedures, such as colonoscopies, are important in individuals who are in the high risk groups for colorectal cancer. However, there are some symptoms that serve as warning signs for colorectal cancer when they do occur.
Two common warning signs of colon cancer include changes in bowel movements and blood in the stools. Changes in bowel movements, which can either involve diarrhea or constipation, are nonspecific symptoms that can be caused by many different medical problems, including irritable bowel syndrome (IBS). Blood in the stools is a less common occurrence, but it can sometimes be mistaken for bleeding hemorrhoids, especially if the blood is coming from the rectum as opposed to further up in the colon. Blood in the stools can appear as bright red if it is caused by rectal bleeding, or very dark if it is caused by bleeding further up in the colon. Other common symptoms that may occur with colon cancer include abdominal pain, intestinal cramping and gas. Nonspecific symptoms such as fatigue are also common. In some cases, weight loss that is not explained by other factors may occur, but not everyone who has colon cancer loses weight.
If any of these symptoms occur, see a doctor. All of the symptoms can be caused by multiple gastrointestinal conditions; colorectal cancer is only one possibility. Other conditions that can cause these types of symptoms include irritable bowel syndrome, diverticulitis, intestinal ulcers, and inflammatory bowel diseases like Crohn’s disease or ulcerative colitis. A doctor may recommend a colonoscopy and/or other medical tests to determine the source of the problems. If nothing can be found by these tests, the most likely cause of the symptoms is irritable bowel syndrome.