Colorectal cancer is one of the most common cancers in the United States and a leading cause of cancer-related death. In 2025, an estimated 154,270 people will be diagnosed with colon or rectal cancer, and nearly 52,900 deaths are expected, according to the National Cancer Institute. One of the biggest challenges is that colon cancer often does not cause clear symptoms in its early stages.
When symptoms do appear, they are often mild and easy to overlook. Changes in bowel habits, abdominal discomfort, fatigue, or unexplained weight loss may not feel serious at first. Understanding what colon cancer symptoms feel like—and recognizing when these changes persist—can help support earlier diagnosis and better treatment outcomes.
March is Colorectal Cancer Awareness Month, a reminder of the importance of symptom awareness, early detection, and timely evaluation. The American Cancer Society ranks colorectal cancer as the third most commonly diagnosed cancer in both men and women, underscoring the life-saving value of early attention to symptoms and screening.
Medical Review by: Mohamad Younes, MD
Board-Certified Medical Oncologist Sub-specializing in Colorectal Cancers
In its earliest stages, colon cancer may not cause noticeable symptoms at all. When symptoms do appear, they are often subtle and may feel similar to common digestive issues. People may notice mild abdominal discomfort, bloating, or changes in bowel habits that come and go. Because these symptoms are not severe, they are sometimes ignored or attributed to diet, stress, or aging.
This lack of obvious symptoms is why screening and diagnostic imaging play such an important role in detecting colon cancer early.
One of the most common colon cancer symptoms involves changes in bowel habits. This may feel like ongoing constipation, diarrhea, or stools that look thinner than usual. Some people feel like they cannot fully empty their bowels, even after using the bathroom.
These changes are most concerning when they last for several weeks or continue to worsen over time. Persistent bowel changes should always be discussed with a healthcare provider.
Colon cancer can cause abdominal discomfort that feels like cramping, pressure, or fullness. The pain may be mild at first and occur off and on. As the cancer grows, discomfort may become more frequent or intense.
Some people also experience bloating or a feeling of fullness that does not improve after eating or using the bathroom. While abdominal pain has many possible causes, ongoing or unexplained discomfort deserves medical evaluation.
Blood in the stool is a common warning sign of colon cancer. It may appear as bright red blood or make the stool look dark or tar-like. In some cases, bleeding is not visible but can still lead to anemia, which may cause fatigue and weakness.
Because rectal bleeding can also be caused by hemorrhoids or other non-cancerous conditions, it is important not to self-diagnose. Any unexplained bleeding should be evaluated by a healthcare provider.
Colon cancer can lead to ongoing fatigue that does not improve with rest. This often happens due to slow blood loss in the digestive tract, which can cause anemia. People may feel unusually tired, weak, or short of breath.
Unintentional weight loss or loss of appetite may also occur, particularly in more advanced stages. These symptoms can feel gradual and may not seem alarming at first, but they are important signals to take seriously.
Patients should contact a healthcare provider if they experience:
Early evaluation may include imaging, colonoscopy, and laboratory testing to determine the cause of symptoms.
When colon cancer is detected early, treatment is often more effective and less invasive. Advanced diagnostic imaging and screening allow providers to identify cancer before symptoms become severe. Early detection gives patients more options and improves long-term outcomes.
Colon cancer symptoms do not always feel dramatic or painful at first. Subtle changes in digestion, bowel habits, energy levels, or weight can be early warning signs. Paying attention to these symptoms and seeking timely medical care can lead to earlier diagnosis and better outcomes.