What Are the Signs of Colon Cancer?

Many patients won’t experience any symptoms in the early stages of colorectal cancer, which is why receiving routine screenings is so important.

Colon Cancer Symptoms

Not every colon tumor strikes without symptoms, however.

Local signs and symptoms are caused by a cancer’s direct effect on the rectum or colon:

  • change in bowel habits, like diarrhea or constipation
  • prolonged change in the consistency of stool, usually longer than a month
  • rectal bleeding or the presence of blood in stool
  • feeling like the bowels don’t empty completely
  • prolonged abdominal discomfort, like cramps, pain or gas

Once a cancer has progressed into later stages, the disease can begin to cause systemic symptoms, ones that involve the entire body:

  • unexplained weight loss
  • loss of appetite
  • weakness or fatigue
  • anemia
  • jaundice

Doctors usually recommend receiving colon cancer screenings beginning at the age of 50, although patients with other risk factors, like a family history of the disease, should probably start earlier than that.

Testing For Colorectal Cancer

Screening works, and it’s become ubiquitous. According to data from the American Cancer Society, thirteen states are currently tied for the lowest rates of colorectal screening among adults over 50, but the lowest rate is itself still relatively high, at 57.1%. In New England, where rates are highest, around 3 out of every 4 adults over the age of 50 receives routine screenings. Along with decreases in associated risk factors, like smoking, screenings have led to a significant decrease in the incidence of colorectal cancers:

  • 1985 – around 68 per 100,000 people diagnosed
  • 1990 – around 61 per 100,000 people diagnosed
  • 1995 – around 56 per 100,000 people diagnosed
  • 2000 – around 54 per 100,000 people diagnosed
  • 2005 – around 49 per 100,000 people diagnosed
  • 2010 – around 44 per 100,000 people diagnosed
  • 2013 – around 40 per 100,000 people diagnosed

Increased screening isn’t just a way to get better statistics. Routine colonoscopies help doctors find pre-cancerous polyps and adenomas. Removing those can actually prevent the development of cancers, and we’ve seen a corollary drop in the rate of colon cancer deaths as a result. Fecal occult blood tests, which look for minuscule amounts of blood in a patient’s stool, have been linked to a 15% to 33% decrease in cancer deaths among patients between 50 and 85.

The only hitch? Colorectal cancer rates in young Americans are rising at an extraordinary rate, although no one is sure why.

Are The Signs Different For Men & Women?


While colon cancers are slightly more common among male patients, both men and women usually exhibit the same symptoms – if they experience any symptoms at all.

Risk factors are generally identical, too:

  • age
  • family history of colorectal disease
  • Crohn’s disease
  • ulcerative colitis

Some lifestyle choices, behavioral patterns and physical characteristics, on the other hand, have also been linked to colon cancer, and these may differ between men and women on average:

  • eating high amounts of red meat
  • lack of physical exercise
  • low intake of vitamin D
  • obesity

Catching Colon Cancer Risks Earlier

In coming years, the “signs” of colon cancer could appear, not externally, but embedded deep within a patient’s genetic code. We already have genetic testing for several hereditary genetic mutations, all of which are classed under the heading “Lynch syndrome,” that can drastically increase the risk for colon cancer. But testing is expensive and time-consuming – like searching for a needle in a haystack.

Now, researchers from Germany’s University of Bonn say they’ve identified a new genetic alteration that leads to polyposis, the development of large numbers of polyps that can become malignant. In the future, testing for changes in the MSH3 gene will be able to clarify diagnoses. Beyond that, we’ll be able to test healthy people from the same family for the mutations, allowing for more proactive surveillance and targeted treatments.

Only 5% to 10% of colorectal cancers are caused by hereditary mutations, however, so genetic testing won’t be a silver bullet. Colonoscopies are here to stay.

How Can We Help?