7 Silent Signs of Colon Cancer

Medically reviewed by: Liza M. Capiendo, MD

The World Health Organization reports colorectal cancer as the third most common cancer and the second leading cause of cancer deaths. So far this year, about 106,970 cases of colon cancer have been reported in the US. The expected deaths as a result are about 52,550 — out of which 3,750 will be young adults.

The good news is that there are cancer screening methods to catch colon cancer early. We also have a good understanding of the risk factors that can increase your chances of developing colon cancer. But the bad news is that it often presents with vague, ill-defined symptoms that are easy to miss if you’re not paying attention. 

  • Enjoy what you're reading? Enter your email address to receive posts like this delivered to your inbox.

  • Hidden

As a result, many patients show up to our practice when their cancer has spread all over their body, limiting their five-year survival rate to only 14%.

So in today’s post, we’ll discuss 7 silent colon cancer signs that should prompt you to get checked.

1. Unintentional weight loss

One of the lesser-known symptoms of colorectal cancer — or any cancer for that matter — is unexplained and unintentional weight loss. Now, some people may brush it off, thinking their weight loss is due to:

  • Stressful situations at work or home
  • A change in eating habits
  • Aging
  • A recent illness like flu or gastrointestinal infection

While all of this can be true, the most important diagnosis that comes to a doctor’s mind when they hear of unexplained weight loss is cancer. This is why it’s extremely important to see a colorectal surgeon if your clothes suddenly start fitting loosely, you notice weight loss on objective measurements, or people start talking about your appearance.

2. Fatigue and weakness

Many colorectal cancer patients report that cancer fatigue feels like everyday fatigue. But when people have cancer, they may feel fatigued even without significant activity. This includes things like:

  • Constantly low energy
  • Sleepiness
  • Poor memory 
  • Difficulty in concentration
  • Inability to carry out basic everyday tasks

If any of these persist without an apparent cause, you should see a doctor. This is especially important if you have a family history of the condition or another risk factor that can predispose you to develop colon cancer.

3. Iron deficiency anemia 

Anemia refers to low hemoglobin levels in the body. Iron deficiency anemia (IDA) is a type of anemia that results from slow, long-term bleeding. 

Unfortunately, right-sided colon cancers are notable for causing this type of bleeding, and it’s not easy to notice in stools because of the small (often microscopic) quantities of blood.

To make things worse, the signs of IDA are not even remotely related to gut function. They include things like:

  • Palpitations
  • Fatigue
  • A craving for dirt or ice
  • Difficulty swallowing
  • Pale nail beds or conjunctiva

The good news is that since the association between IDA and colorectal cancer is well-known, it’s standard medical practice to screen adult males with IDA for colon cancer. 

4. Narrow stools

Narrow or stringy stool is another colon cancer sign that’s easy to ignore. The thin, pencil-like shape of the stool means that there’s an obstruction in your gut. This is especially true for left-sided cancers.

Now, narrow stools can be associated with other health conditions as well, such as:

  • Irritable bowel syndrome
  • Inflammatory bowel disease (Crohn’s disease and ulcerative colitis)
  • Hemorrhoids 
  • Infections

But in all these conditions, they are often paired with other prominent symptoms like abdominal pain, diarrhea, bright red blood in stools, and constipation. 

5. Blood in stool (not always visible)

Rectal bleeding is the most alarming symptom of colon cancer. However, early bleeding is minimal and you may not notice bright red blood in stools. But you can observe darker-colored stools (sometimes even black). If this is present, it’s a clear indicator that there’s bleeding within your gastrointestinal (GI) tract.

Keep in mind that bleeding within the gastrointestinal tract doesn’t always mean cancer. Patients with ulcers, benign polyps, diverticulitis, and inflammatory bowel disease can all experience GI bleeding. But since it can also mean cancer, it’s always better to consult a healthcare provider if you notice it.

6. Constipation or diarrhea 

Since constipation and diarrhea are symptoms of many other health conditions and can be caused by changes in diet/lifestyle, we do not recommend counting on this symptom alone to suspect colon cancer.

Observe your bowel movements and look for other signs described on this list before making an assumption — and of course, always consult a doctor to confirm your suspicion.

With that said, health experts recommend seeking medical help if:

  • Diarrhea lasts more than 24 hours and occurs every few days
  • Constipation lasts more than three days and has been occurring for more than 3 weeks

Note that both constipation and diarrhea can worsen other colon cancer symptoms, such as fatigue and weakness. 

7. Cramping or bloating

Cramping refers to the painful nagging or burning sensation in the abdomen. Bloating refers to uncomfortable tightening or fullness in the abdomen.

These symptoms are among the earliest signs of colon cancer but are easy to dismiss. So, if you’ve been experiencing cramping/bloating on a regular basis — for more than three weeks — it’s best to report to your doctor. This is especially important if you’re 45 years or older, in which case your doctor will screen you for colon cancer according to the recommendations of the American Cancer Society.

Now you know colon cancer signs to look out for

As you may have noticed, many silent colon cancer signs — such as weight loss, fatigue, diarrhea, and constipation — are easy to miss if you’re not paying attention. Others — like narrow or bloody stools — are more obvious but many people are not aware they could mean cancer.

We hope you’re more aware of how colon cancer can present. If you think you have any of the signs we’ve described above, reach out to one of our colorectal surgeons immediately. We’re more than happy to help. 

Frequently asked questions about silent colon cancer signs

Does colon cancer cause gas?

Yes, colon cancer can cause gas trapping. An average person passes gas about 13 – 21 times a day. If there is a growth inside the colon, this gas can become trapped, leading to pain and discomfort. If you are unable to pass gas and have other symptoms like chronic constipation or diarrhea, narrow stools, and unexplained weight loss, you should consult a doctor immediately.

Where is colon cancer pain felt?

Colon cancer pain is usually felt in the lower abdomen. Left-sided cancers are more commonly associated with pain compared to right-sided cancers. In addition, colon cancer pain is described as colicky, meaning it waxes and wanes in intensity but doesn’t fully subside. 

What are the most overlooked symptoms of colon cancer?

The most overlooked symptoms of colon cancer include constant fatigue, weight loss, changes in bowel habits, and abdominal cramps. If you’re experiencing any of this for a long period, see a doctor now. 

  • Enjoy what you're reading? Enter your email address to receive posts like this delivered to your inbox.

  • Hidden