6 Signs of Bowel Cancer (Small or Large Intestines)

Bowel cancer is one of the more dreaded types of cancer these days as it is the second most common cancer that can affect men and women and among the deadliest. The term bowel refers to the intestines, both the small and large intestines. Overall small intestine cancer is rare compared to cancer of the colon and/or rectum (large intestine). Therefore most people refer to the large intestine and colorectal cancer specifically when they talk about bowel cancer.

How To Spot Bowel Cancer

There are many signs and symptoms that arise with bowel cancer. These symptoms can be due to many different bowel conditions. For example, rectal bleeding may be seen with inflammatory bowel disease (IBD) or hemorrhoids (piles). Therefore depending on the symptoms alone is not a reliable way to diagnose bowel cancer. Furthermore, in the early stages there may be little to no symptoms.

Diagnostic investigation should be done to spot bowel cancer. This includes investigations like a colonoscopy which allows for the area to be visualized. Tissue samples can also be collected (biopsy) for further examination. People who are at high risk of bowel cancer should undergo these routine screening investigations on a regular basis.  Overall it is difficult to spot bowel cancer by the symptoms without conducting relevant tests and scans.

Read more on small intestine cancer.

Where is bowel cancer located?

The location of bowel cancer can vary in the small or large intestines. The small intestine starts at the upper middle abdominal region. The first part of the small intestine is known as the duodenum and leads directly from the stomach. Measuring almost 7 meters (approximately 23 feet) long, the small intestine coils to occupy a large part of the abdominal cavity. The small intestine then continues into the large intestine.

The large intestine is approximately 5 feet in length. It starts at the cecum which is located at the lower right region of the abdomen, runs upwards to the right upper quadrant of the abdomen (ascending colon), across the upper abdomen (transverse colon) and then down the left side of the abdomen (descending colon). From here the sigmoid colon extends towards the midline where it connects to the rectum that ends at the anus.

Bowel cancer can be located anywhere along the length of the small and large intestine. However, it is the colon and rectum (colorectal cancer) that is most commonly affected. Colorectal cancer is more likely to occur in the sigmoid colon and rectum. Colon cancer tends to be more common in women while rectal cancer is more likely to occur in men. Both the colon and rectum can be affected simultaneously and this is more likely to occur in advanced cases.

Warning Signs

The three main warning signs that occurs with bowel cancer is blood in the stool, a change or abnormality in bowel habit like diarrhea or constipation and abdominal pain. However, as mentioned these signs and symptoms may occur with other non-cancerous bowel conditions. Non-specific symptoms like fatigue or unintentional weight loss should further raise the concern about bowel cancer especially in high risk individuals. The signs and symptoms discussed below are more likely to be seen in colorectal cancer.

Read more on signs of colon cancer.

Blood in the Stool

This is often the most worrying sign for most people but it is important to remember that rectal bleeding is often due to other conditions, like hemorrhoids. The bleeding may be overt where the stool is coated with blood or even reddish in color compared to the typical tan to dark brown hue. Sometimes the blood may even stain the water in the toilet during defecation and soil underwear. However, very often it is less conspicuous and only noticed when wiping after a bowel movement where blood or streaks of it are noticed on the toilet paper.

Changes in Stool

The other common sign of bowel cancer is a change in bowel habit or consistency of the stool. Either diarrhea or constipation can occur. Many people report frequent bowel movements of even diarrhea with loose stool. This type of change in bowel habit is not uncommon. We all experience diarrhea occasionally usually due to conditions like viral gastroenteritis or food poisoning. However, a change in bowel habit that persists for a long period (more than 4 weeks), especially when there is a blood in the stool, should raise the concern about bowel cancer.

Pain in the Abdomen

Abdominal pain or cramping is another symptom that commonly occurs with bowel cancer. Since colorectal cancer is the more common bowel cancer, the pain is usually felt in the lower abdomen. It should be correlated with changes in bowel habit or stool consistency as well as bleeding in the stool in order for bowel cancer to be suspected. Abdominal pain is a common symptom of various conditions and sometimes occurs for short periods of time with no clearly identifiable cause.

Incomplete Bowel Emptying Sensation

Bowel cancer may also present with a sensation that the bowel movement was not complete, in that all the stool was not expelled. There may also be an abnormal urge to pass stool even after a bowel movement. Despite trying, a person may not be able to defecate. This sensation is known as tenesmus. As with many of the other signs and symptoms described above, this abnormal sensation is not unique to bowel cancer.

Unintentional Weight Loss

Unintentional weight loss should be considered as a red flag sign when it accompanies a persistent change in bowel habit, blood in the stool, lower abdominal pain and an feeling that the bowel is not completely empty after passing stool. This is a common sign in many different types of cancer. Similarly it may occur with non-cancerous conditions but usually it is a serious sign, especially when there has been sigicant loss of body weight.

Fatigue and Weakness

Fatigue and weakness are non-specific symptoms that occurs with many diseases and disorders. The abnormal tiredness and lack of physical strength should also not be considered in isolation but correlated with the other symptoms above. Collectively these signs and symptoms point towards bowel cancer. Fatigue and weakness that is ongoing and worsening with time is always a serious symptom.


  1. www.cancer.gov/types/colorectal/patient/colon-treatment-pdq
  2. www.merckmanuals.com/professional/gastrointestinal-disorders/tumors-of-the-gi-tract/colorectal-cancer

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