Difference Between IBS and Colon Cancer

Colon cancer and irritable bowel syndrome (IBS) are two long standing conditions which affect the large bowel. Because both conditions share some symptoms, some may mix the two up. It is always better to have a clear idea on how to differentiate the two, to prevent unnecessary misery. 

Colon Cancer

Large bowel, also known as the colon consists of the caecum, ascending colon, transverse colon, descending colon, and sigmoid colon. The sigmoid colon continues into the rectum. Lower colon and rectum are more frequently affected in colon cancer. Bleeding per rectum, feeling of incomplete evacuation, alternative constipation, lethargy, wasting, loss of appetite, and loss of weight and diarrhea are the presenting features of colon cancer. Inflammatory bowel diseases and genetics are well known risk factors for colon cancer. Inflammatory bowel disease increases cancer risk due to high cell renewal rate. Risk of getting colon cancer is much greater if a parent or a sibling had it.

Sigmoidoscopy or colonoscopy is the best investigation to diagnose colon cancer. On examination pallor, wasting, and liver enlargement may be evident. A biopsy, which is a small piece of the growth, is removed to be examined under the microscope, to determine whether the tissue has cancerous features. Severity of spread determines the treatment plan. Magnetic resonance imaging (MRI), computed tomography (CT) and ultrasound scans help assess the local and distant spread. Ancillary investigations also give clues towards other complications and fitness for surgery. Carcinoembryonic antigen is one chemical detectable in colon cancer, which helps diagnose colon cancer with a high degree of certainty.

Colon cancer is preventable and low intake of red meat, and intake of fruits, vegetables and regular physical activity reduces the risk of getting colon cancer. Drugs like aspirin, celecoxib, calcium and vitamin D also reduce colon cancer risk. Complete surgical resection with adequate margins to either side of the lesion cures localized colon cancer. Chemotherapy increases life expectancy if there is nodal spread.

IBS (Irritable Bowel Syndrome)

Irritable bowel syndrome is a disorder characterized by long standing abdominal pain, bloated sensation, constipation and diarrhea. No definite cause has been found for irritable bowel syndrome. It is actually a functional disorder named because of the regular association of same symptoms. It can be classified according to the predominating symptom. If diarrhea predominates, the condition is called IBS-D; if constipation predominates, the condition is called IBS-C, and if diarrhea and constipation alternates, it is called IBS-A.

If the disease sets in before the age of 50, without bleeding per rectum, weight loss, fever, confusion or family history of inflammatory bowel disease, the diagnosis of irritable bowel syndrome can be made on symptoms alone. Routine investigations do not show any abnormality in irritable bowel syndrome. Irritable bowel syndrome tends to set in or aggravated after infections and stressful events. There is no definite cure for irritable bowel syndrome. Dietary adjustment, anti-inflammatory medication and psychological therapy help control the disease.

Irritable Bowel Syndrome vs Colon Cancer

• Irritable bowel syndrome sets in early while colon cancer is common after the age of 50.

• IBS presents with alteration of bowel habits mainly while bleeding per rectum is the major presenting feature of colon cancer.

• Weight loss, loss of appetite, and inflammatory bowel diseases are closely associated with colon cancer while they are not associated with IBS.

• Surgery is almost always the best option in localized colon cancer while surgery rarely plays a part in the management of irritable bowel syndrome.