5 Common Signs of Colon Cancer That Are Easy to Overlook

6 min read

5 Common Signs of Colon Cancer That Are Easy to Overlook

The thought of colon cancer can be scary— especially being that it’s the third most common cancer in both men and women. Unfortunately, symptoms don’t manifest themselves until the disease has become more advanced. With that said, many people will have signs of the disease at an early stage— many of which can be overlooked. Because of this, depending on your age, family history, and other risk factors, we at Rocky Mountain Cancer Centers (RMCC) recommend regular screening for colon cancer with your primary care physician.  Like all cancers, it is best to catch and treat colon cancer early, so if you notice any of these five signs, be sure to schedule an appointment with your doctor.

Understanding Colorectal Cancer


1. Unexplained weight loss

Unexplained weight loss isn’t just a sign of colon cancer, but other cancers as well. If you lose more than ten pounds over a few months without trying, it’s worth looking into. 

Colon cancer can lead to unexplained weight loss in different ways. Sometimes, the cancer can cause a decrease in appetite. Other times, the cancer grows to the point of causing a partial or even a total bowel obstruction. Regardless, either situation can be dangerous, putting you at risk for loss of muscle mass and malnutrition as well. 

2. Fatigue and weakness 

Sometimes, fatigue can be confused with tiredness. However, they are not the same. Tiredness can usually be remedied by sleep and rest. On the other hand, cancer-related fatigue is different, often being described as feeling tired, weak, worn-out, heavy, slow, or having no energy or get-up-and-go. As the disease progresses, the body may allocate a significant amount of energy to combat the cancer, leading to persistent fatigue. Individuals experiencing prolonged fatigue, even after adequate rest, should seek medical advice to identify potential underlying causes.

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3. Abdominal cramps

Depending on the location of the tumor and other factors, some people with colon cancer may not experience abdominal pain (cramping) until the disease is in its later stages. However, for others, abdominal pain can be an early sign of colon cancer. 

Keep in mind that abdominal pain can result from other issues including non-cancerous conditions like hemorrhoids and irritable bowel syndrome. Still, if you are experiencing abdominal pain that started recently, is severe, and unexplained by some other condition, it is time to talk to your doctor. 

4. Blood in the stool 

The presence of blood in the stool is a significant red flag that should never be ignored. While conditions like hemorrhoids can cause rectal bleeding, persistent or unexplained bleeding should prompt immediate medical attention. Colon cancer can lead to bleeding within the digestive tract, and the blood may mix with stool, resulting in visible changes. Distinguishing between bleeding caused by minor issues and those that may be indicative of a more serious condition is crucial. In some cases, this blood may be bright red and very noticeable. It may appear on its own, or you may notice it only with bowel movements. In other cases, blood from colon cancer may turn the stool darker. Bleeding can also be so mild that you don’t see it. 

While blood in your stool may have many causes it should always be reported to your doctor— especially if it happens more than once. 

5. Changes in bowel habits

Bowel changes like constipation, diarrhea, or narrow stools can be normal if they are temporary. However, if they don’t go away after a few days, you should definitely mention them to your doctor as they are one of the first signs of colon cancer. Colon cancer can disrupt the normal functioning of the colon, leading to these changes. Diarrhea may result from the body's inability to absorb water properly, while constipation may arise due to the obstruction caused by the tumor. Paying attention to these signs can be crucial in identifying potential issues early on. 

Again, these changes can be attributed to other less serious conditions, such as irritable bowel syndrome. Still, you should always see a doctor to rule out cancer when bowel habits change and don’t go back to normal. 

Remember, if you notice any of these— or any other signs of colon cancer— don’t ignore them. Please make an appointment with your doctor as soon as possible for testing to rule out cancer. Additionally, if you are over the age of 50 or are at high risk of developing this disease, it is also important to schedule colon cancer screenings as recommended by your physician.


Get Screened for Colorectal Cancer

Screening is important because it can prevent colorectal cancer by finding anything abnormal and treating it promptly before it develops into cancer. When cancer is found early, it allows for a better chance to treat the cancer and save your life. 

While colonoscopies are the standard when it comes to screening for colorectal cancer, individuals who are considered average-risk may be able to utilize some at-home testing kits, especially before the age of 50. Be sure to check out our blog about What to Know About At-Home Colon Cancer Tests.

If you’re at least 45 years old with an average risk of colorectal cancer, it’s the right time to be proactive and ask your doctor about screening. The ACS also encourages you to start screening younger than age 45 if you have a high risk of this type of cancer.  

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Updated January 2024