Colon cancer may seem to be of rare occurrence, not like other cancer types such as breast or lung cancer but is the third most common form of cancer and is the second leading cause of cancer-related death in the United States. It is a type of cancer that affects the colon, the longest part of the large intestine. These cancerous growths can extend to the rectum and other organs. Most often, colon cancers are adenomatous polyps, mushroom-like growths that start benign and develop into cancer over time. It is often called COLORECTAL CANCER, when the affected cells migrate down to the rectum, the last inches of the large intestine before the anus.
In 2008, the National Cancer Institute has reported that colon cancer statistics is on the rise. In the United States, an estimated new cases of 108, 070 has colon while 40, 740 cases was reported to have rectal cancer. In the same year, deaths from both colon and rectal cancer were estimated to be 49, 960.
A colon cancer prognosis is good when detected early, when it is removed before it spreads to other parts of the body. But when the cancer has grown deep and through the wall of the colon, it most likely has spread. The main treatment for this cancer is surgery, curing almost 90% of cancer that is along the lining of the bowel wall, 70% are cured when cancer has extended through the bowel wall, and only 30-50% curability when the cancer has spread and affected the lymph nodes of the abdomen. Surgical removal of visible cancer may lengthen survival time.
Rectal cancer, on the other, depends on how deep it has grown into the rectal wall and how far the cancer has spread, with other words the colon cancer stages. Patients with rectal cancer that has metastasized the colon cancer treatment would require a complete removal of the rectum and the anus. This leaves the patient with a permanent colostomy, an opening surgically created between the large intestine and the abdominal wall. This facilitates emptying of the contents of the large intestine straight through the abdomen and into a colostomy bag.
Colon cancer presents with different types:
ADENOCARCINOMA – adenomacarcinoma is the most common colon cancer type, accounting to about 90-95% of all colorectal cancer. This type of cancer originates in the glands and is divided into two subtypes – mucinous and signet ring.
LEIOMYOSARCOMAS – this cancer type affects the smooth muscles of the colon. It accounts for less than 2% of all colorectal cancer but has a fair chance of spreading to other parts of the body.
LYMPHOMAS – lymphomas are a rare type of cancer and which start in the rectum more than the colon. Other than the rectum, lymphomas can start from other parts of the body then metastasize to the colon. One common lymphoma is Non-Hodgkin’s lymphoma, which accounts for 0.5% of all coloncancer.
MELANOMAS – melanomas are a rare form which starts from other parts of the body then spread and affect the colon or the rectum. 2% of all colorectal cancers are melanomas.
NEUROENDOCRINE TUMOR – this type is subdivided into two:
a. aggressive neuroendocrine tumor – these include large cell and small cell neuroendocrine tumor
b. indolent neuroendocrine tumor – an example is carcinoid tumors