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Colorectal cancer is a condition that involves cancerous growth in the colon, rectum and the appendix. It is also called colon cancer. It is responsible for more than six lac deaths a year. It is considered to be the most common form of cancer coming fourth in the list of cancer causing conditions. It is the third reason for cancer related deaths in the Western World. This condition is also called bowel cancer. The cancerous growths are mushroom shaped and normally are found to be benign. They are seen to originate from polyps of the adenomatous variety in the colon. These benign growths turn cancerous later on. A colonoscopy is done to trace out cancer in a particular area of the colon.
Surgery is a good way of treating cancer of the invasive variety. These are limited to the walls of the colon. When they are left untreated they spread to the Stage III of cancer i.e. cancer of the lymph nodes. In the lymph node type of cancer three fourths of the cases are curable by surgery and chemotherapy. But any cancer that has progressed into the Stage IV cannot be treated as it has overgrown the curable stage.
Chemotherapy only ensures the person lives for some more time. It does not guarantee cure. But of course there are those rare cases when people have survived chemotherapy and a surgery. In case of rectal cancer, radiation therapy is adopted.
What is colorectal cancer and how does it start? Colorectal cancer begins when the wnt signaling pathway facilitates a mutation. When a receptor is bound to a wnt then a chain of events is augmented. These molecular events end with a beta catenin getting into motion into the nucleus and thus a gene in the DNA is activated. However in case of colorectal cancer, the genes along the same chain get mutilated and damaged. This gene that is damaged, is called APC is also called a brake and is damaged in the wnt pathway.
Normally the detection of the tumor is had from a tissue analysis. This tissue is got after the biopsy or the surgery. A report of pathology of the colorectal cancer normally describes the cell type and the grade of the cancer. Adenocarcinoma is the most common colon cancer. This is found in ninety five percent of the cases. The other types include lymphoma and squamous cell carcinoma.
The cancer that is found on the ascending colon has a tendency to be exophytic. This means that the tumor grows outwards. It grows in the bowel wall from one area. This is not found to obstruct the feces. It comes with symptoms like anemia. There are also left sided tumors that grow around. These have the chances of obstructing the bowel motion like a ring.
What is colorectal cancer and adenocarcinoma? Adenocarcinoma is a tumor of the malignant variety. It takes birth from the glandular ephithelial cells of the mucous in the colorectal area. It grows into the wall and perpetrates into the muscularis mucosae, the submucosa and then the muscularis proparia. Sometimes these tumor cells secrete mucus and sometimes it doesn’t. Thus depending on this pattern the cancer takes it shape.
The U.S. National Comprehensive Cancer Network and American Society of Clinical Oncology has got proper rules for the way colon cancer has to be followed up. There is a medical and a physical examination. This is done every three to six months for the next two years. Carcinoembryonic antigen blood tests are taken for patients with T2 or for patients having greater lesions. Sometimes there are patients who have a greater chance of recurrence. For such patients a CT scan of the chest, a CT scan of the abdomen and pelvic area are recommended. These apply to patients suffering from venous tumors or lymphatic growths. For such people, a colonoscopy is done after a year. If it was not done in the beginning because of obstruction, then it is done after three or six months. If there is a villous polyp then the colonoscopy is done after three years. There is a routine PET or sonography with chest X-rays and a complete blood count taken along with functioning of liver. But these are not really medically recommended.
It there is a villous polyp which is more than 1 cm then it is repeated after three years. The colonoscopy can be repeated after one year if and when necessary. Care has to be taken well.
