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What color are colon cancer symptoms?

Colon cancer, also known as colorectal cancer, is a cancer that starts in the colon or rectum. It is the third most common cancer diagnosed in both men and women in the United States. The American Cancer Society estimates there will be over 100,000 new cases of colon cancer diagnosed in 2022. While colon cancer can occur at any age, it is most commonly found in people over the age of 50. Early detection through screening is key, as colon cancer is highly treatable when caught early. But what do the symptoms of colon cancer actually look like? Are there visual signs that could serve as early indicators of the disease? In this article, we’ll explore what color colon cancer symptoms may appear and what that could signify about one’s health.

What Are the Most Common Colon Cancer Symptoms?

Some of the most common colon cancer symptoms include:

Symptom Description
Changes in bowel habits This includes constipation, diarrhea, or stool shape changes that last more than a few days
Blood in the stool Blood can make stool appear either bright red or very dark/black
Abdominal pain Pain, bloating, cramps, or gas pains in the abdomen
Unexplained weight loss Losing weight without trying or explanation
Fatigue Feeling very tired all the time for no reason

These symptoms can also be caused by other, less serious health conditions. But it’s important to talk to a doctor if any last more than a few days so the cause can be diagnosed.

What Does Blood in Stool Look Like?

One of the most common and recognizable colon cancer symptoms is blood in the stool. Blood in stool can take on different appearances:

Bright Red Blood: Stool with bright red blood or red streaks often indicates bleeding in the lower colon or rectum. This type of bleeding is usually from hemorrhoids, anal fissures, diverticulosis, or colon polyps. However, it can also come from colon cancer located close to the rectum.

Dark/Black Stool: Very dark or black stool often means there is bleeding farther up in the colon or small intestine. The blood has had longer to travel and digest, making it appear very dark. This type of blood in stool can be a sign of growths or cancer in the upper digestive tract.

Occult/Invisible Blood: Sometimes colon cancer bleeding is not visible to the naked eye. This is known as occult or invisible blood. Special tests are needed to detect the presence of occult blood in stool.

So the visibility, color, and consistency of blood in stool can give clues about potential sources of bleeding in the colon, but additional testing is needed for an accurate diagnosis.

What Are Some Other Visual Symptoms?

In addition to blood in stool, other visual symptoms that may arise from colon cancer include:

Pencil-thin Stools: Thin, narrow stools that resemble the shape of a pencil can be a sign of potential blockages in the colon. These blockages could be caused by colon polyps or cancers.

Ribbon-like Stool: Stool that is very flat and ribbon-like could also indicate a partial blockage in the colon, especially if it occurs frequently.

Mucus: Excess mucus in stool relates to irritation and inflammation in the colon. While not inherently a sign of cancer, it could indicate precancerous conditions.

Pale or Clay-Colored: Very pale or clay-colored stool can indicate a lack of bile from the liver. Bile helps digest fats and give stool its normal brownish color. If bile flow is blocked, it could signify liver or gallbladder issues that warrant further testing.

These visual symptoms often lead to diagnosis of colon cancer, but can also result from other digestive conditions. Discuss any perplexing or persistent changes in stool with your doctor.

What Does Poop Look Like if You Have Colon Cancer?

If someone does have colon cancer, what are some specific changes that may occur in their stool? Some to watch for include:

  • Long, thin stools, often described as pencil-thin
  • Mucus coating on stool
  • Visible blood – anywhere from dark streaks to bright red
  • Diarrhea or loose stools lasting more than 3 days
  • Stool that is more narrow than usual for that person
  • Foul stool odor

Again, many of these visual and textural changes can result from conditions other than cancer. And not all colon cancer cases will result in obvious changes to stool. But noticing these differences should prompt a doctor’s visit to identify the underlying cause. Tracking stool qualities that seem abnormal provides valuable information for diagnosis.

What Other Symptoms May Accompany Stool Changes?

While alterations in stool offer early signs, colon cancer can cause other symptoms as it develops. Some additional symptoms to watch for include:

Abdominal Pain: Persistent pain, cramps, bloating, and gas pains in the abdomen often arise. This discomfort comes from blockages and internal bleeding.

Fatigue: The cancerous cells impair your body’s ability to absorb nutrients from food. This can lead to constant tiredness or weakness.

Unexplained Weight Loss: Poor nutrient absorption and appetite changes cause unintentional weight loss. This occurs in about 40% of colon cancer patients.

Nausea & Vomiting: Digestive system irritation, intestinal blockages, constipation, or obstruction can trigger nausea.

Paying attention to concurrent symptoms provides a fuller picture and context for changes in bowel movements. Discuss all ongoing and related symptoms with your physician.

When to See a Doctor

If you notice any of the colon cancer symptoms described, make an appointment with your doctor promptly. While many causes are possible, the only way to identify the source is through an exam, diagnostic tests, and possibly a referral to a specialist like a gastroenterologist. Do not wait to see if symptoms resolve on their own.

Waiting to seek care may allow the cancer to spread further and lower survival rates. Catching colon cancer early greatly improves prognosis. According to the American Cancer Society, localized stage colon cancer has a 90% 5-year survival rate. Once it spreads regionally, the survival rate falls to about 70%. And once the cancer metastasizes to distant organs and areas, the 5-year survival dips to 14%.

So do not brush off worrisome toilet bowl findings or abdominal complaints. Blood in stool, pencil-thin stools, constipation, diarrhea, cramping, fatigue, nausea, or vomiting should be evaluated immediately. Early detection, diagnosis, and treatment are critical.

When to Get Screened for Colon Cancer

Symptoms aside, colon cancer screening improves early detection in people with no outward signs of the disease. Screening tests can find precancerous polyps in the colon so they can be removed before becoming cancerous. Or they may uncover cancer in its earliest stages when it is most readily cured.

The U.S. Preventive Services Task Force recommends regular colon cancer screening from age 50 to 75. Those with a family history or high risk factors should begin screening earlier.

Some of the most common screening options include:

Test Frequency
Colonoscopy Every 10 years
Fecal immunochemical test (FIT) Every Year
Flexible sigmoidoscopy Every 5 years
CT colonography Every 5 years

Talk with your doctor about which colon cancer screening makes sense for your situation and family history. Screening identifies many colon cancers before they start causing symptoms. Adhering to the recommended screening timeline improves your chances of finding and treating any cancer early.

Can You Detect Colon Cancer by Stool Color?

While certain stool colors can provide clues about colon cancer, stool color alone is not a definitive indicator of colon cancer. The many potential causes of color changes include:

Reddish Stool: Foods like beets, tomatoes, red fruit, red sauces, or food coloring can redden stool. Hemorrhoids and anal fissures can also lead to streaks of bright red blood. And darker red to maroon stool may contain digested blood from higher in the colon.

Black/Dark Brown Stool: Substances like iron supplements, black licorice, blueberries, or even black candy can darken stool. Black stool is also caused by bleeding in the upper digestive tract.

Green Stool: Green vegetables, iron, or supplements can add a greenish tinge. Excess mucus also makes poop appear green. Rapid transit time through the colon produces yellow-green stool as well.

Yellow/Pale Stool: Gallbladder or liver issues that impair bile production make stool pale. Excess fat in stool from malabsorption may appear yellow or orange.

So while stool color can provide helpful clues about potential health issues, it does not directly diagnose colon cancer. Screening tests and colonoscopies are needed to actually detect cancer.


Colon cancer symptoms often involve changes in the color, consistency, shape, or frequency of stool. Blood in stool, visible either as bright red streaks or very dark coloring, is a classic symptom and sign of potential cancer. Other symptoms like pencil-thin stools, ribbon-like stool, mucus, or unusual paleness also warrant follow up. If you notice ongoing changes in your stool, along with symptoms like abdominal pain, fatigue, nausea, or unexplained weight loss, see a doctor right away for evaluation. Waiting may allow the cancer to advance further. While stool color can indicate problems, a full work up is needed to diagnose colon cancer. So do not delay in reporting symptoms – early detection and treatment provides the greatest chance for remission and survival. Consistent colon cancer screening between ages 50-75 is equally important for finding cancer in the absence of symptoms.


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