The doctor may remove polyps by polypectomy. If you have stage 0 colon cancer, your doctor may also suggest removing the tumor through the anus. Otherwise, your doctor may suggest surgery if any of the following situations apply to you:
- You've had a colonoscopy, but the doctor could not completely remove a polyp. Surgery is then needed to remove the rest of the polyp. That's because it might contain cancer cells that could spread to your lymph nodes. The only way to know if a polyp is cancerous is to remove all of it and examine it under a microscope.
- You've had a polyp completely or partially removed, and that polyp has invasive cancer cells in it. Your doctor will be able to tell this by looking at the polyp under a microscope. Surgery may be needed because the cancer may have spread to your lymph nodes. If your doctor thinks the cancer has not spread, you may not need surgery.
- You have a stage I, II, or III colorectal cancer. These cancers have not spread to distant sites, so surgery may be able to remove all of the cancer. Other treatments may be needed as well.
- You have stage IV colorectal cancer, but it has only spread to areas of the liver or lungs that can also be removed with surgery. Surgery on both the main tumor and the site of metastasis may be able to remove all of the cancer in selected cases.
- You have advanced cancer that threatens to block (obstruct) the colon or cause other major problems. In these cases, surgery may be used not to try to cure the cancer, but to correct the problem and relieve symptoms. For example, if the colon is blocked by a tumor, surgery may be done to create a colostomy (connecting the part of the colon before the obstruction to an opening in the skin of the abdomen, which allows wastes to leave the body).
If you have cancer in your rectum, you may have chemotherapy and/or radiation therapy before surgery. Treatments before surgery are called neoadjuvant therapies. This may help shrink the tumor and allow your surgeon to take it out without removing your sphincter muscles. This is called sphincter-saving surgery. The anal sphincter is a circular muscle that allows you to hold stools inside until you are ready to have a bowel movement. Sphincter-saving surgery will allow you to resume normal bowel habits after your surgery.
If you need another treatment after surgery, it's called adjuvant therapy. You might need chemotherapy or radiation therapy. You could have both. The purpose is to reduce the chance of the cancer coming back and increase your chance for survival. These other treatments, though, are not substitutes for removing the tumor with surgery.