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This article explains the signs that can sometimes occur with colon cancer, who may be at increased risk, how the disease is diagnosed, and why screening remains so important.Medical Tests & Exams
1. A Persistent Change in Bowel Habits
One of the most important warning signs is a change in the way your bowel normally functions.
This can include constipation, diarrhea, or alternating between the two.
The key word is persistent.
Everyone experiences occasional constipation or diarrhea. A change in diet, travel, stress, infection, medications, or food intolerance can temporarily alter bowel movements.GERD & Digestive Disorders
Colon cancer can sometimes affect the passage of stool through the intestine, potentially changing how frequently a person has bowel movements or what they look like.
A person may notice that their usual pattern has changed and does not return to normal.
For example, someone who normally has regular bowel movements might suddenly experience constipation for several weeks without an obvious explanation.Health
Another person might develop persistent diarrhea.
Neither symptom proves cancer.
But a lasting change deserves medical evaluation.Cancer
2. Blood in the Stool
Blood in the stool is another symptom that should never simply be dismissed.
Blood may appear bright red, dark red, or sometimes make the stool look black and tar-like.
The appearance can provide clues about where bleeding is occurring, although only medical evaluation can establish the cause.
Colon cancer can cause bleeding from a tumor inside the intestine.
However, there are many other explanations.
Hemorrhoids and anal fissures are common causes of bright-red blood.
Inflammatory bowel disease, infections, polyps, diverticular disease, and certain medications can also cause gastrointestinal bleeding.Anatomy
Because some causes are serious and others are relatively minor, it is important not to assume that visible blood is “just hemorrhoids.”
If you notice unexplained blood in your stool, contact a healthcare professional.
3. Unexplained Weight Loss
Losing weight without trying can be a warning sign of many illnesses, including cancer.
Colon cancer may affect appetite, metabolism, digestion, or the body’s ability to process nutrients.
A person may notice that clothing becomes looser even though they have not intentionally changed their eating or exercise habits.
Unexplained weight loss is not specific to colon cancer.Health Conditions
Thyroid disease, infections, digestive disorders, diabetes, depression, medication effects, and other cancers can also cause it.
Nevertheless, significant unexplained weight loss deserves medical attention.
It becomes particularly important when it occurs together with bowel changes, abdominal pain, fatigue, or blood in the stool.
4. Persistent Abdominal Pain or Cramping
Abdominal pain is extremely common.
Most abdominal pain is not caused by cancer.
However, colon cancer can sometimes cause persistent discomfort, cramping, bloating, or abdominal pain.GERD & Digestive Disorders
The pain may be intermittent or continuous.
Some people may experience cramps around the time they need to have a bowel movement.
Others may notice discomfort after eating.
The exact symptoms depend on the location and characteristics of the tumor and whether it is affecting the normal movement of stool through the colon.
Persistent or worsening abdominal pain should be evaluated, especially when it occurs alongside other changes.
Severe or sudden abdominal pain can represent an emergency and should receive urgent medical attention.
5. Feeling That Your Bowel Doesn’t Empty Completely
Some people with colon cancer report a sensation that they still need to have a bowel movement even after using the toilet.Health
This feeling is sometimes called tenesmus.
It can occur when something affects the rectum or lower part of the colon.
But there are other causes, including hemorrhoids, inflammatory bowel disease, infections, and other gastrointestinal conditions.
If this sensation persists or is accompanied by bleeding, pain, changes in stool, or unexplained weight loss, it should be discussed with a healthcare professional.
6. Narrower Stools