Colon Cancer: Etiology and Treatment - Continued (page 2 of 4)

First: Was the polyp completely removed and can a line (margin) of normal tissue along the edge be identified? Often large, sessile(flat) polyps cannot be removed in one piece, thereby raising the possibility of incomplete and therefore inadequate removal and the inability to determine whether all of the polyp or cancer was removed.

Second: Where were the malignant cells in the polyp? If the cells were present at the resection margin (the edge), then adequate resection cannot be presumed and tumor cells may have been left behind.

Third: Are there any adverse or bad features seen by the pathologist that might signal that a cancer may behave in an aggressive manner. These are features such as poor differentiation or lymph vascular invasion? These findings raise the risk that tumor may spread through the lymph system to the lymph nodes and therefore may prompt your surgeon to recommend a part of the colon should be removed.

Last: Will the patient return for colonoscopies in the future, and will those colonoscopies be able to be performed with low risk? Patients may find the procedure embarassing and uncomfortable and may not return for a repeat evaluation despite the risk of colon cancer.

In studies that looked a surgeries where a portion of the colon was removed, 10 percent of patients who had malignant polyps, polyps with cancer cells in them, were found to have tumor cells which had spread to the lymph nodes. All of these patients had sessile (flat) polyps with invasion at the edge of the polyp removed, or their cancers had aggressive features under the microscope. Based on these studies and evaluation of all the above factors, it is recommended that part of the colon should be removed when a sessile polyp contains cancer cells, when the polyp is incompletely removed or when aggressive pathologic features are present. All other patients should be followed by repeat colonoscopy in 6-12 months.

Most colon cancers, however, will be discovered at a point when they cannot be removed during a colonoscopy. This leaves surgical removal as the mainstay of treatment and staging for colon cancers. Colon resections for cancer are based on the premise of removing the tumor-bearing segment of colon and its associated lymph nodes. Resections are generally based on the vascular anatomy to enable complete removal of the associated lymph nodes. Because the colon and the upper rectum and their blood supply are usually easily accessible, removal and reconnection can generally be accomplished without the need for a colostomy. This is also done safely with a risk of recurrence in that segment of less than 4 percent. If the cancer has invaded other organs, then removal of the tumor and these other organs in one piece is the treatment of choice. Approximately 50 percent of invasion will actually be because of the cancer cells, with the other 50 percent representing inflammation causing the organs to stick together.