Gas and Bloating as Signs of Colon Cancer

Causes and Symptoms

Stomach issues/ Upset stomach
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Gas and bloating can happen anytime and for any number of reasons. They can be caused by something as simple as swallowing air or eating the wrong foods. Less often, gas and bloating are signs of something imminently more serious, ranging from intestinal disorders to potentially life-threatening malignancies in the lower digestive tract, such as colorectal cancer.

Common Causes of Gas and Bloating

The two main causes of gas are swallowed air and the breakdown of food that leads to the production of gas. The latter is especially true when foods are high in sugar, starch, or fiber. On average, our bodies expel gas anywhere from 14 to 23 times per day. It's perfectly normal and a part of everyday life.

Bloating, on the other hand, is caused by an accumulation of gas in the intestines. While this could also be food-related, it may be a sign of irritable bowel syndrome (IBS), a common disorder that makes you sensitive to the presence of gas even if levels are normal.

Gas and Bloating as Symptoms of Cancer

While it's too big of a leap to suggest that gas and bloating are early warning systems for cancer, they can, in fact, be the first sign if they are persistent and/or getting worse.

This is because a tumor in the colon can cause obstruction, which is basically a roadblock that can make passing stools increasingly difficult.

Depending on the severity of the blockage, solids, liquids, and even gas may be prevented from passing through.

A pattern of gas and bloating may be an indication that a tumor is growing, especially if it worsens or is accompanied by bleeding. While the formation of a tumor may not be enough to cause a total obstruction, the increasing pressure placed on the colon walls can cause distress and even cramping in the upper intestinal tract.

What to Do If Symptoms Persist

The persistence of gas, bloating, pain, cramping, and bloody stools aren't something you should ignore. At the very least, they warrant a series of investigations to check for inflammation and/or the causes of intestinal bleeding. This is especially true if you have a family history of cancer.

Treating yourself with over-the-counter remedies may help relieve symptoms but does nothing to pinpoint the underlying cause. With a physical exam, abdominal X-rays, and other tests, your doctor can determine if the problem is simple or if it warrants further investigation.

Other Symptoms of Colon Cancer

While the symptoms of colon cancer can often be vague and easily chalked up to other conditions, the combination of symptoms can often point us in the direction of an early diagnosis.

Common symptoms of colon cancer include:

  • feeling like you need to have a bowel movement even when you don't
  • changes in bowel movements, including diarrhea or constipation, that last for more than 10 days
  • changes in stool color, ranging from purple or black (melena) to bright red (hematochezia)
  • unintended weight loss
  • stools that are narrower than usual
  • constant tiredness
  • unexplained anemia


American Cancer Society. What is Colorectal Cancer? Updated April 6, 2017.