Medically reviewed by Neka Miller, PhD on June 15, 2020. To give you technically accurate, evidence-based information, content published on the Everlywell blog is reviewed by credentialed professionals with expertise in medical and bioscience fields.
Table of contents
In the United States, bowel cancer—also called colon or colorectal cancer—is the third most common form of cancer in both men and women (excluding skin cancer). Overall, the lifetime risk of developing colorectal cancer is 1 in 23 for men and 1 in 25 for women.
Knowing the possible early signs of bowel cancer can help inform you when discussing symptoms you’ve been experiencing with your healthcare provider—so keep reading to find out more, plus learn about the stages of colon cancer and what screening options exist (such as an at-home colon cancer screening test). We’ll begin by covering some of the early warning signs, listed below.
Because colorectal cancer can cause bleeding in the digestive tract, rectal bleeding is among the possible early signs of bowel cancer. Blood might appear bright or dark red in color. Sometimes, the blood might be seen in the stool, or the blood might simply make the stool appear darker. Keep in mind, though, that rectal bleeding doesn’t always appear with colorectal cancer, and—instead—stool may look completely normal.
If you regularly feel the urge to have a bowel movement, but you don’t pass much (or any) stool, this may be something to pay attention to (and discuss with your healthcare provider). The reason why? It could be because of tenesmus—a possible sign of colon cancer. Tenesmus is a term for frequently feeling like you have to empty your bowel—but no or very little stool passes.
Another one of the early signs of bowel cancer is persistent abdominal pain. This discomfort is brought on after eating and can often lead to a reduction in the amount of food eaten. Cramps and gas are common, too.
There are many possible reasons you might feel fatigued, but unrelenting exhaustion is a possible sign of colon cancer. So if you’re noticing an overwhelming feeling of sluggishness and weakness, there may be something serious going on in your body—and it’s worth discussing this with your healthcare provider.
Sudden, unexplained weight loss is another one of the common early signs of colon cancer. Of course, sudden weight loss can be caused by other things too, like an overactive thyroid, depression, or an infection. Remember, if you aren’t trying to lose weight but the pounds are dropping, there might be an underlying health issue—so talking with your healthcare provider is a good idea.
When considering early signs of bowel cancer, a change in bowel habits can be an indication. In particular, a greater frequency of bowel movements and looser stool may be a sign of colon cancer. Additionally, narrow, ribbon-like stools (sometimes described as “pencil-thin”) are also among the potential early signs of bowel cancer.
Patients with metastatic colorectal cancer—colorectal cancer that has spread to other parts of the body—may experience a number of possible symptoms. Symptoms might depend on the size of the tumors as well as where the cancer has spread—as described in this section.
Pain, fractures, constipation, and high calcium levels
Difficulty breathing, shortness of breath, coughing, pain, fatigue
Swollen feet and hands, nausea, jaundice, fatigue, jaundice
Bloating, swollen abdomen, loss of appetite
Pain, memory loss, confusion, headache, blurred vision or double vision, seizures, difficulty speaking
If left untreated, colorectal cancer passes through a number of different stages, which we’ll touch on here.
Stage 0 refers to colorectal cancer that’s in situ, meaning the cancer cells are only found in the inner lining of the colon or rectum. These can often be removed with a local excision, or if necessary, a partial colectomy (removal of the area of the colon with the cancerous cells).
During stage I of colorectal cancer, the cancer has spread from the inner lining of the colon or rectum and into the muscular layer—but it hasn’t spread to other tissues or lymph nodes.
When the cancer has spread beyond the colon wall but hasn’t yet made it to the lymph nodes, it’s referred to as stage II.
Stage III refers to cancer that has spread past the lining of the colon to the lymph nodes. Other than the lymph nodes, however, the cancer hasn’t spread to other organs in the body.
In stage IV, cancer has moved through the blood and the lymph nodes and spread to other organs in the body.
Colorectal cancer typically develops from polyps—clusters of cells on the lining of the colon that can potentially become cancerous. These can be detected through screening tests and removed to help prevent the development of colorectal cancer. Additionally, because colon cancer often shows no symptoms until it progresses, screening tests can identify it in the early stages when it’s easier to treat.
When should you begin screening for colon cancer? According to the U.S. Preventive Services Task Force, people who are age 50-75 and have an average risk should screen for colon cancer once a year. However, screening more frequently may be recommended if you have certain risk factors—so ask your healthcare provider how often you should get screened.
Related: Who is at risk for colon cancer? | Signs of colon cancer in women
The following tests are commonly used to screen for colon cancer.
This kind of test detects tiny traces of blood in the stool (invisible to the eye), which can indicate the presence of polyps in the colon or cancerous growths. One kind of fecal occult blood test is the fecal immunochemical test, or FIT.
Fecal immunochemical tests are highly accurate and can correctly determine if someone has colorectal cancer nearly 80% of the time. You can use a fecal immunochemical test to easily screen for colon cancer from the comfort of home with the Everlywell at-home colon cancer screening test.
Stool DNA tests analyze your DNA from a stool sample to look for molecular indicators of precancerous growths or colon cancer.
A colonoscopy allows a healthcare professional to look inside the entire colon for polyps. This is done with a flexible tool called a colonoscope.
Sometimes called a virtual colonoscopy, this is used as a bowel screening alternative for those who can’t undergo the anesthesia used during a traditional colonoscopy. It may also be used if someone has a blockage in the colon that prevents a full examination.
During a sigmoidoscopy, a flexible tube is inserted into the rectum and lower colon to look for abnormalities and polyps. Polyps can be removed for examination and to prevent colorectal cancer.
With this test, an enema containing barium is administered to help the colon show up on x-rays. This test isn’t usually recommended, though, as it’s less likely to detect precancerous polyps.
For easy, comfortable colon cancer screening at home, take the Everlywell FIT Colon Cancer Screening Test.
7 signs of colon cancer in women
24 colon cancer statistics to know in 2020: risk factors, diagnosis, and survival
We asked a Registered Nurse what you should know about colon cancer screenings—here’s what she said
1. Key Statistics for Colorectal Cancer. American Cancer Society. URL. Accessed June 15, 2020.
2. Colorectal Cancer Signs and Symptoms. American Cancer Society. URL. Accessed June 15, 2020.
3. Understanding Advanced Cancer, Metastatic Cancer, and Bone Metastasis. American Cancer Society. URL. Accessed June 15, 2020.
4. Vatandoust S, Price TJ, Karapetis CS. Colorectal cancer: Metastases to a single organ. World J Gastroenterol. 2015;21(41):11767-11776. doi:10.3748/wjg.v21.i41.11767
5. Treatment of Colon Cancer, by Stage. American Cancer Society. URL. Accessed June 15, 2020.
6. Tests to Detect Colorectal Cancer and Polyps. National Cancer Institute. URL. Accessed June 15, 2020.
7. Lee JK, Liles EG, Bent S, Levin TR, Corley DA. Accuracy of fecal immunochemical tests for colorectal cancer: systematic review and meta-analysis. Ann Intern Med. 2014;160(3):171. doi:10.7326/M13-1484