Dr. Tejinder Kataria, Chairperson Radiation Oncology, Cancer Center, Medanta – The Medicity
Colon cancer occurs in the first part of large intestine covering approximately 15 cms length. Colon is followed by rectum and anal canal, the terminal parts of the digestive system. The annual age adjusted rate of incidence of colon cancer in India is 4.4/100,000 men and 3.9/100,000 women as per the National Registry. The risk of colon cancer is higher after the age of 50 years, in family members of people having colon cancer and in people having a tendency to colonic polyps (Hereditary polyposis coli). Alcohol, cigarette smoking and obesity are a few of the pre-disposing factors for colon cancer.
The symptoms of colon cancer include feeling tired and laboratory tests may show a low level of haemoglobin due to micro-bleed; weight loss >10% in 6 months, alternating diarrhoea and constipation, the passage of fresh blood in stools, feeling of having a persistent urge for bowel evacuation, abdominal discomfort.
Colon cancer can be prevented by having a high intake of green vegetables, and fruits, a high fibre diet, avoiding constipation and addictive substances, and increasing physical activity. A few studies have shown that taking a small dose of aspirin may protect against colon cancer, however, large studies are required for this to be confirmed. Removal of polyps through colonoscopy can prevent the development of frank colon cancer.
A colonoscopy is recommended in a person with a family history of colon cancer after 50 years of age and it is recommended to be done every 2 years. However, for someone with a colon cancer diagnosis colonoscopy is recommended every year. A tumour marker-CEA or carcino emeryonic antigen may be high is a certain percentage of patients with colon cancer, however, confirmation is done only with a biopsy.
Role of Radiation in treating colon cancer
The main stay of treatment for colon cancer is surgery followed by chemotherapy depending upon the stage of the disease. However, a small percentage of patients with T3-T4 disease i.e. when the tumor has come out of the wall of colon and infiltrated the surrounding structures, may benefit with localized radiation treatment.
Colon cancers can spread to liver or lung and stereotactic body radiotherapy(SBRT), a few fractions of high dose radiation are curative for >80% of colonic cancer metastases.