Colon cancer is cancer of the large intestine, and is also known as colorectal cancer. In colon cancer, tumours develop in the lining of the large intestine and rectum.
The tumours develop over a period of years and generally start out as non-cancerous growths called polyps. Over time, these polyps can become cancerous. If these polyps are caught early, colon cancer can be prevented.
Signs and symptoms
Symptoms of colon cancer, especially in the early stages, tend to overlap with symptoms of IBD:
Blood in the stool
Change in frequency of bowel movements
Stools that are narrower than usual
Alternating bouts of diarrhea and constipation
Abdominal bloating, fullness, or cramps
Vomiting, fatigue, weight loss
Because these symptoms are so similar to those of IBD, having IBD is a risk factor for colon cancer.
Risk factors for colon cancer when you have IBD include:
having IBD for more than 10 years
having extensive inflammation
being diagnosed with IBD under the age of 20
having a diagnosis of primary sclerosing cholangitis (PSC)
and the presence of polyps or abnormal changes to the cells lining the colon
Luckily, the overall risk of colon cancer in IBD patients is decreasing due to better control of inflammation and the use of colonoscopies to find polyps and other pre-cancerous changes.
Treatment of colon cancer
Colon cancer is highly treatable. If detected early, it has a 90% chance of being cured. The key is early detection. All patients with IBD should have a colonoscopy with biopsy at regular intervals. The cells removed in the biopsy will be examined for cancerous or pre-cancerous changes.
If you are diagnosed with colon cancer, you, your gastroenterologist, an oncologist, and the rest of your healthcare team will work together to manage it.
Treatment may consist of surgery, radiation, and chemotherapy. Treatment will depend on the location of the tumour, how advanced it is, and whether or not it has metastatized (spread to other areas of the body).
Prevention of colon cancer
Lifestyle choices can play a role in the development of colon cancer. To decrease your risk:
eat a healthy diet and avoid fat, red, and processed meats
maintain a healthy weight
drink alcohol in moderation (in men: no more than two drinks a day; in women, no more than one drink per day)
Because Crohn’s disease can affect the small intestine, patients have a higher risk of small bowel (small intestine) cancer. IBD-related small bowel cancer tends to arise more frequently in patients who have been diagnosed with Crohn’s disease for more than eight years, especially if there is stricture.
Anal cancers can arise in the fistulas
of patients who have had Crohn’s disease for more than 10 years. This type of cancer is hard to diagnose because the lesions can be difficult to see if there is narrowing of the intestine.
Lymphoma is a cancer that arises in the lymph nodes and other parts of the immune system. The risk of lymphoma is higher in patients with IBD. Lymphoma typically arises in chronically inflamed lesions of middle-aged men with Crohn’s disease after eight years of diagnosis.
If you are diagnosed with cancer, you, your gastroenterologist, an oncologist, and the rest of your healthcare team will work together to manage it. Treatment is individual to the patient and the type of cancer.