Unfortunately, colorectal cancer may strike without symptoms. For this reason, it is very important to have regular examinations, called colorectal screenings, to detect early problems.
However, not all colorectal cancers are without symptoms. One of the early symptoms of colon cancer may be bleeding. Often, tumors bleed only small amounts, off and on, and evidence of the blood is found only during chemical testing of the stool. When tumors have grown larger, other symptoms may develop. They include:
Note: Separate PDQ summaries on Colorectal Cancer Screening; Colon Cancer Treatment; and Rectal Cancer Treatment are also available.
Factors Associated With Increased Risk of Colorectal Cancer
Excessive alcohol use
Based on solid evidence from observational studies, excessive alcohol use is associated with an increased risk of colorectal cancer (CRC).[1,2,3]
Magnitude of Effect: A pooled analysis of eight cohort studies estimated an adjusted relative risk (RR) of 1.41 (95% confidence...
Change in bowel habits. Constipation, diarrhea, and bowel incontinence, although usually symptoms of other, less serious, problems, can also be a sign of colorectal cancer.
Blood on or in the stool. By far the most alarming of all the symptoms, blood on or in the stool can be a symptom of colorectal cancer. But, it does not necessarily indicate cancer. Numerous other problems can cause bleeding in the digestive tract, including hemorrhoids, ulcers, ulcerative colitis, and Crohn's disease, to name only a few. In addition, iron and some foods, such as beets, can give the stool a black or red appearance, falsely indicating blood in the stool. However, if you notice blood in your stool, see your doctor to rule out a serious condition and to ensure proper treatment is received.
Unexplained anemia. Anemia is a shortage of red blood cells, the sort that carry oxygen throughout the body. If you are anemic you will most likely feel tired and sluggish, so much so that rest does not make you feel better.
Unusual stomach or gas pain
Unexplained weight loss
If you experience any of these symptoms, it is important to see your doctor to ensure proper diagnosis and treatment. For a patient with colorectal cancer, early diagnosis and treatment can be a lifesaver.