In the early stages of colon cancer, there can be no obvious symptoms and it is only detected during physical exams because of elevated tumor markers and other reasons.
As the disease progresses, there can be a change in bowel habits and disruption of the original bowel pattern. It can be accompanied by a change in the nature of the stool, alternating between diarrhea and constipation, as well as mucus stools or mucus and blood stools.
In right-sided colon cancer, there is a tendency to have a change in the nature of the bowel movement, with diarrhea and constipation, which is associated with alternating decreased and hyperabsorption of water by the colon.
Sigmoid colon cancer, on the other hand, is prone to changes in bowel habits, which can be accompanied by changes in abdominal pain, mucus stools, and mucus and blood stools.
A few others, however, can present with increased farting for no known reason. However, these symptoms are not specific and can also be seen in changes such as irritable bowel syndrome as well as enterocolitis, which requires colonoscopy to determine the cause.