Colorectal Cancer Awareness Month is observed in March every year to highlight the importance of screening for colorectal cancer, as well as to promote healthy lifestyle habits that can decrease a person’s risk of developing cancer of the colon and rectum.
Colorectal cancer is the third most common cancer worldwide. Almost 2 million cases are diagnosed every year. It is the second most common cause of death due to cancer, leading to almost 1 million deaths per year. It is estimated that the incidence of colon cancer will increase by almost 50% in the next 20 years. Most of this increase is expected to occur in countries transitioning to the developed world and this includes large parts of Asia and Middle East.
The major risk factors for colon cancer are a diet rich in red meat, processed meat, obesity, alcohol use, tobacco use and a family history of colorectal cancer.
It is important to understand that 80 to 90% of all colorectal cancer develops from polyps in the colon and rectum. Polyps are overgrowth of the mucosal lining of the colon. Polyps are very common and occur in 30% of individuals above the age of 50. Most of these polyps are non-cancerous and not of significance. However, some of these polyps are pre-cancerous and can evolve into cancer over 10 years. These precancerous polyps which are also known as adenomatous polyps can be easily detected and removed during a colonoscopy procedure. The whole idea of preventing colon cancer is to detect polyps and remove them before they evolve into cancer. It is important to remember that polyps and early cancers do not cause any symptoms and therefore without screening, it is not possible to detect them.
The best way to detect polyps is to perform periodic colonoscopies. Currently it is recommended that all individuals above the age of 45 should have a colonoscopy once every 10 years. Those with a strong family of colon cancers or a personal history of colon polyps may need colonoscopy more frequently about once every 5 years.
Another way to screen for polyps and early cancers is to do a stool test and check for presence of occult blood. The stool occult blood test is recommended for those who are not willing to have a colonoscopy. The stool occult blood test should be done once a year. However, it is important to understand that stool occult blood test may be positive only if there is a large polyp or an actual cancer. It may not be positive with small polyps and cancers that do not bleed. At the same time a positive stool occult blood test does not always mean the presence of cancer. There are many other reasons that can lead to a false positive stool occult blood test. Therefore, while a stool occult blood test is a very simple test, it is not as accurate in detecting polyps as a colonoscopy. Individuals who test positive for stool occult blood definitely need a colonoscopy.
There are other innovative ways to detect polyps and early colon cancer. There is stool DNA test. This test is based on the principle of detecting genetic changes in the colon mucosal lining cells that are shed in the stool. Individuals who have high risk pre-cancerous polyps or actual cancers have genetic changes in their cells and these are detected by the stool DNA test. It is recommended to do the stool DNA test once every two years.
Another technique to detect colon polyps is virtual colonoscopy. In this technique an individual undergoes a special CT scan after inflation of the colon with air. A special software is used to reconstruct the colon in a form that can help detect colon polyps. Once colon polyps are suspected on a virtual colonoscopy, the individual can then undergo a regular colonoscopy to remove this polyps. Having a normal virtual colonoscopy can help avoid a regular colonoscopy. A virtual colonoscopy is recommended once every 5 years after the age of 45 years.
All in all, colorectal cancer is a preventable cancer and the good news is that majority of colon cancers and related deaths can be prevented by regular screening for colorectal cancer. Lifestyle modifications such as maintaining normal body weight, regular exercise, avoiding excess alcohol and smoking cessation helps prevent colorectal cancer as well as many other cancers. Avoiding red meat, processed meat and instead having diet rich in vegetables, fruits and fish also reduces the risk of development of colorectal cancer. Finally it is important to participate in colon cancer screening by having a colonoscopy once every 10 years or at least having a stool occult blood test once a year after the age of 45 years.
