Medical professionals often refer to colorectal cancer, which includes colon cancer that affects the large intestine and rectal cancer that affects the lower most part of the large intestine.

According to the American Cancer Society, 1 in 20 people are at a risk of developing colorectal cancer during their lifetime.

The exact cause of colorectal or bowel cancer is not known. However, it is believed to develop when healthy cells become abnormal and start growing in number and accumulate in the lining of the colon, forming polyps. Left untreated, polyps may become cancerous.

Several factors increase your risk of developing colon and rectal cancer, including aging (above 50 years), some types of bowel diseases, family history, obesity, smoking, excessive alcohol intake, a sedentary lifestyle, Type 2 diabetes and regular intake of processed foods or red meats.

African-Americans are at a greater risk of colon cancer than people of other races.

As it can be difficult to treat colon cancer after it spreads to nearby areas, it is important to know what the early symptoms are. This can help you seek early treatment and give you a better chance in recovery.

Here are the top 10 warning signs of colon cancer you shouldn’t ignore.

1. Constipation

Constipation is an important sign of cancer in the colon. A 2011 study published in the Asian Pacific Journal of Cancer Prevention highlights the link between constipation and colorectal cancer risk.

An earlier 2004 study published in the European Journal of Cancer supported the hypothesis that constipation or laxative use increases the risk of colon cancer.

A tumor present at the far end of the colon can make it very difficult to eliminate waste products, thereby causing constipation.

If you persistently have fewer bowel movements per week, without any prior problem of constipation, consult your doctor to find out the exact cause.

2. Diarrhea

If you suffer from diarrhea for more than a couple of weeks, it may be an early symptom of colon cancer.

When a tumor partially obstructs the bowel, it can cause alternating constipation and diarrhea due to leakage of liquid stool.

You may also experience frequent gas, abdominal pain, nausea and vomiting. Plus, a tumor may irritate or narrow the lining of the intestine.

It is important to consult your doctor when you have diarrhea that lasts more than a few days, as it can lead to dehydration, drain your body of nutrients and signal other serious problems, such as cancer.

3. Blood in Stools

Most often, blood in the stool is due to piles (hemorrhoids), where the veins in the back passage become fragile and cause a little bleeding during a bowel movement. This type of bleeding is generally red.

However, if you notice dark red or black blood in your stool, it can be a sign of cancer, such as bowel, rectal or colon cancer. It can also be due to a stomach ulcer.

Whether bleeding is due to piles, a stomach ulcer or cancer, it’s important to get it checked by a doctor. Proper diagnosis is essential for appropriate treatment.

4. Constant Feeling of a Bowel Movement

If you have a constant feeling of urgently needing to have a bowel movement or to strain but no stool is passed, it is not a good sign. This feeling can occur even after having a bowel movement.

Changes in your pattern of bowel movements can be a sign of colon cancer. It can occur when a tumor blocks the bowel and prevents you from completely emptying your bowels.

If you persistently have the sensation of incomplete evacuation after a bowel movement, discuss the problem with your doctor.

5. Narrow Stools


Thin, narrow stools are also a warning of possible colon cancer. A tumor present in the left side of the colon obstructs the passageway and often leads to narrow stools.

Do not delay discussing any change in your stools with your doctor. Diverticulitis and anal cancer can also cause narrowing of the stools.

6. Tender Abdomen or Abdominal Pain

If your abdomen, especially the lower part, hurts or feels tender when touched, this can be an early indication of tumor growth in the digestive tract, colon or rectum. In fact, abdominal pain is common in people who are later diagnosed with colon cancer.

A tumor can cause a block in the colon, restricting blood flow. This leads to abdominal pain that can be severe. This pain also can indicate that the cancer has begun to spread to other organs.

If abdominal pain or tenderness persists for more than 2 to 3 days, consult your doctor for proper diagnosis.

7. Unexplained Anemia

Anemia refers to a low red blood cell count in the body. The hemoglobin in red blood cells carries oxygen throughout the body.

Symptoms of anemia, such as pale skin, a fast or irregular heartbeat, shortness of breath, dizziness, and cold hands and feet, should not be taken lightly.

Unexplained anemia may be due to colon cancer. Typically, cancer in the right-side of the colon causes iron-deficiency anemia. This happens when tumors start bleeding slowly into the digestive tract, causing blood loss over time.

A 2008 study published in the British Journal of Cancer confirms a strong connection between anemia and cancer, with the risk rising as the hemoglobin level falls. This study also confirms iron deficiency as an independent predictor of cancer.

If you have signs of anemia, consult your doctor immediately to get your hemoglobin level checked.

8. Unexplained Weight Loss

If you are above the age of 50 and rapidly losing weight without any known reason, it is a cause for concern. Sudden, unexplained weight loss can indicate a serious health problem, including colon or rectal cancer.

A 2006 study published in the Annals of the Royal College of Surgeons of England found that unexplained weight loss happens mostly during advanced stages of colorectal cancers.

The growth of a tumor can lead to loss of appetite, as cancer can affect your metabolism, thus causing weight loss.

If you are rapidly losing weight without changing your diet or exercise routine, discuss this with your doctor.

9. Weakness and Fatigue

Another early symptom of colon cancer is fatigue, weakness and general malaise. Fatigue and tiredness after doing a laborious task is to be expected, but if you feel tired and weak most of the time, despite resting, do not take it lightly.

Large polyps or tumors in the colon can lead to iron-deficiency anemia that causes lower oxygen levels in the blood. This contributes to fatigue.

Fatigue and weakness can also be related to a number of chronic illnesses and medical disorders, sovisit your doctor to find outthe exact cause.

10. Gas and Bloating

Most people suffer from gas and bloating occasionally, but if the problem occurs along with some of the other symptoms mentioned here, it may be an indication of a tumor growing in the colon.

A tumor causes obstruction in the colon. Depending on the severity of the blockage, gas, solid and liquid may be prevented from passing out of the body. This in turn causes progressive bloating as well as gas.

If you have a lot of discomfort due to gas and bloating, see a doctor to rule out the possibility of cancer.

Tips to reduce your risk of colon cancer:

  • Include a variety of fresh fruits, fresh vegetables and whole grains in your diet.
  • Avoid drinking alcohol, or at least drink in moderation.
  • Stop smoking and use of other tobacco products.
  • Exercise for at least 30 to 40 minutes, 5 times a week.
  • If you are overweight, take steps to lose weight gradually.
  • Opt for regular screening tests to help prevent colon cancer


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