Published On: Mon, Apr 3rd, 2017

Know the Signs of Colon Cancer

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34Colon cancer is cancer that starts in the colon.  This is very similar to cancer that starts in the rectal area and the two types, colon and rectal cancers, are often grouped together and called colorectal cancer.  These cancers usually arise from polyps which are growths in the colon.  There are generally two types of polyps.  The first type are adenomatous polyps.  These are pre-cancerous. The second type is hyperplastic polyps.  These polyps are not considered precancerous.  The number of polyps that are present in the colon can increase the risk of cancer developing.  If there are more than two polyps seen in the colon, the risk of colon cancer increases.  If a polyp has pre-cancerous changes within it, the risk of colon cancer also increases.  Having polyps larger than 2 cm can indicate a higher risk of developing colon cancer.

Incidence and Prevalence

35Colorectal cancer is the third most common cancer diagnosed in both men and women in the United States.  The American Cancer Society estimates that for 2017 there will be 135,430 new colorectal cancer cases and 50,260 related deaths in 2017[1].  Colorectal cancer is the second leading cause of cancer deaths for men and women combined.

Death rates for colon cancer has decreased over several decades.  This may be related to increased and better screening and removal of polyps.  Earlier detection as a result of those efforts can lead to earlier treatment with less resulting deaths.

Conditions affecting colon cancer risks

There are conditions that increase the risk of developing colon cancer.   Being overweight or obese increases the risk of colorectal cancer.  Also, being physically inactive increases the risk.  Smoking increases the risk of colon cancer.

Diets that have a lot of red meat and processed meats make individuals more prone to colon cancer.   It is thought that even the way meats are prepared may increase risk.  Frying, broiling, grilling or cooking meats at high temperature may increase risk.

The risk of getting colon cancer increases after age 50.  Having Type 2 Diabetes Mellitus increases risk. Anyone with a history of past polyps or colorectal cancer have a higher chance of developing further cancer in the colon.  Those who have a history of inflammatory bowel disease, such as Crohn’s disease or ulcerative colitis have an increased risk.  According to the American Cancer Society about 5% to 10% of colorectal cancers are in individuals who have some inherited genetic mutations that can cause family cancer syndromes that increase the risk of colon cancer in families.  Having a family member who has history of adenomatous polyp or colorectal cancer increases the chances of having colon cancer.

In the United States, African Americans have the most colorectal cancers and associated deaths.  On a worldwide basis, Jews of Eastern European descent (Ashkenazi Jews) are the ethnic group with the highest chance of developing colorectal cancer.1

There are some factors that lower colon cancer risk.  Having a diet that has lots of vegetables, fruits and whole grains actually lower your cancer risk.  Drinking no more than 2 drinks per day for men and 1 drink per day for women may lower colorectal cancer risk.  However heavy alcohol use increases the risk.


The goal in colorectal cancer, as in all cancers, is to first prevent it from occurring whenever possible and to find it early if there is cancer present.   There are screening tools available to help prevent and detect early stages of this type of cancer.  Yet only about half of the people who should get screened for colon cancer get it.

Removing colon polyps is the principal way to prevent colon cancer.  This can be done with colonoscopy or flexible 2sigmoidoscopy.  Colonoscopy is a procedure where the entire colon is examined with a scope passed through the anus.  Images can be seen and biopsies can be taken and polyps can be removed.  Flexible sigmoidoscopy is the same procedure done to examine the lower part of the colon and rectum.

In individuals with colon related diseases, such as inflammatory bowel disease, having colonoscopy to examine the colon for possible precancerous changes can allow preventive measures to be taken in case there are changes seen.

Other tests are available to detect early colon cancers or polyps.  A radiology study called a double-contrast barium enema can be done. This test involves placing a substance through an enema into the colon that allows the colon to be examined on a CT scan.  A CT colonography can also be done.  This is a special 3-D CT scan of the colon which is like a virtual colonoscopy.

There are tests of the stool that can help detect early colon cancer.  A fecal occult blood test is done on stool smeared on a special card and to which is applied a special chemical liquid.  It can allow for detection of microscopic amounts of blood.  Another similar test is the fecal immunochemical test(FIT).  A third test that can be performed on stool is the Stool DNA test.   A specimen is collected and sent to a lab that examines it for DNA that could indicate colon cancer.

It is recommended that individuals with low risk for colon cancer start screening at age 50.  This is the recommendation of the two major organizations that set standards, the American Cancer Society and the Unites States Preventive Services Task Force (USPSTF).  The USPSTF recommends that screening continue until age 75.

Individuals with increased risk should start screening at earlier ages.  Individuals at increased risk include those with previous polyps or colorectal cancer, inflammatory bowel disease, family history for adenomatous polyps or colorectal cancer or family history of a genetic condition that increases colorectal cancer risk.    Individuals at increased risk should consult with their medical provider to determine when they should start screening since the recommendation depends on the exact cause for the increase risk.

Genetic screening

For those individuals who may have a genetic mutation that increases the risk for colorectal cancer, there are genetic tests available.  It is recommended that those individuals consult with a genetic counselor

Signs and Symptoms

There are some symptoms that could possibly indicate that there is colon cancer present.  According to the American Cancer Society, the symptoms include[2]:   3

  • A change in bowel habits, such as diarrhea, constipation, or narrowing of the stool, that lasts for more than a few days
  • A feeling that you need to have a bowel movement that is not relieved by having one
  • Rectal bleeding with bright red blood
  • Blood in the stool, which may make the stool look dark
  • Cramping or abdominal (belly) pain
  • Weakness and fatigue
  • Unintended weight loss

Although there may be other explanations for these symptoms or they may be very nonspecific, the presence of these symptoms should be brought to the attention of a medical provider to investigate.

Treatment and Prognosis

Finding colorectal cancers early is key to having better survival.  For cancers found early before spreading, 90% of the affected individuals will survive to 5 years.  Eighty percent of this type of cancer is found at this early stage.  Cancers that have spread have a much lower survival rate.

Treatment for colorectal cancer is based on how early it is found and how extensive the disease is. For disease that has not spread to other organs the treatment options are surgery, radiation therapy and ablation (destroying with radio waves, chemicals or cold) or embolization (where the cancer blood supply is cut off).    Diseases that have spread outside the colon can be treated with chemotherapy or other targeted therapy depending on the stage of the cancer.


It is important that patients consult with their medical providers about screening for colorectal cancers.  Early detection through screening can lead to much better survival and less illness than cancers that are found later in their course when they cause symptoms.  All concerning symptoms should be discussed with a medical provider.

[1]  Accessed 3/17/2017


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