Colorectal cancer is the third most common cancer worldwide. The number of new cases has been increasing rapidly in the past 20 years. The global burden of colorectal cancer is expected to increase by 60% to more than 2.2 million new cases and 1.1 million deaths by 2030. Colon cancer is fairly equal in both men and women, but in the case of rectal cancer, men are more affected than women. Colorectal cancer incidence among people of age group 50 years and above is dropping 5% annually from the year 2000 onwards. In contrast, there is a steady rise - up to 22% - among people younger than 50 years.
Colorectal cancer, more often detected in people younger than 50 years, is a matter of real concern. It is primarily found that the recent changes in lifestyle, food habits and lack of physical activity are the leading causes.
Causes of colorectal cancer
Causes of colorectal cancer can be broadly divided into modifiable and non-modifiable causes. Modifiable factors are obesity, smoking, fatty meals, red meat (more than 500gm/week - beef, lamb, pork, liver), processed meat (hot dog, steaks), lack of physical exercises, alcohol consumption, lack of fibres, fruits, vitamins (vitamin B6, vitamin D), folic acid and minerals (calcium and magnesium) in the diet. Non-modifiable causes are older age, ethnicity, and personal or family history of ‘adenomatous polyp’ or cancer, history of inflammatory bowel diseases, history of inherited cancer syndromes (FAP or HNPCC, etc)
Colorectal cancer usually presents with bleeding through rectum, usually noticed by dark or red colour blood staining with stool. Sometimes, stool contains mucus or passage of mucus with blood. Other symptoms are recent changes in the bowel habits (alternating diarrhoea and constipation), weakness or fatigue, anaemia, recent constipation, abdominal cramps or pain, and unintended weight loss.
Those who are having any of the symptoms of colorectal cancer should consult a Gastroenterologist. A thorough history, physical examination followed by a colonoscopic examination with biopsy will be helpful in confirming the diseases. Once the disease is confirmed, it will be further ‘staged’ by a CT scan or MRI test. According to the stage, an expert can advise the further treatment of the disease.
Is it preventable?
This is one of the types of cancer that we can prevent through early detection by means of screening methods. Screening is the process of looking for cancer or pre-cancer in people who have no symptoms of the disease. Regular colorectal cancer screening is one of the most powerful tools for preventing colorectal cancer. Most of the cancer cases start as polyps; it usually takes about 10-15 years from them to develop into colorectal cancer. With regular screening, most polyps can be found and removed before they have the chance to develop into cancer.
If you are 45 years or older, you should start getting screened for colorectal cancer. Several types of tests can be used. Faecal blood occult test is a stool-based examination which can be used to detect blood in the stool even when it is not visible by naked eyes. This test could be continued annually. Other tests include sigmoidoscopy and colonoscopic examination that has to be done at 5 -10 years interval. If you have a strong family history of colorectal polyp or cancer, talk with your doctor about your risk. You might benefit from genetic counselling to review your family medical tree to see how likely it is that you have a family cancer syndrome. People with inflammatory bowel disease also need early screening.
How to treat a colorectal cancer?
Surgery is the primary treatment, which can be done by open or laparoscopic methods. Chemotherapy with or without radiotherapy may also be needed depending on the stage and location of the disease. Sometimes chemotherapy or radiotherapy may be needed even before surgery in advanced stages. Unlike other cancers, colorectal cancer can be cured even in stage 4 diseases (spread to other organs such as liver, lung, etc.).
How to follow-up?
Follow-up in the first 5 years after treatment should be more frequent because chance of recurrence is more in the first 5 years. Physical examination and blood test (CEA) are needed every 3 -6 months interval for 5 years. Yearly CT scan and colonoscopic examination are also needed for 5 years.