health

The first step in treating colorectal cancer is called staging. Staging
describes the location of the cancer, its size, how far it has penetrated into
healthy tissue, and whether it has spread to other parts of the body. Colorectal
cancers are classified into five stages:

• Stage 0: The cancer has not grown beyond the lining of the colon
  or rectum.
  
• Stage I: The cancer has penetrated through the lining of the colon
  or rectum into the underlying tissues but has not spread beyond
  the colon wall.
  
• Stage II. The cancer has grown through the wall of the colon or
  rectum but has not yet spread to nearby lymph nodes.
  
• Stage III. The cancer has spread to nearby lymph nodes but has
  not yet affected other organs.
  
• Stage IV. The cancer has spread to other organs. This process of
  spread is called metastasis. The most common locations of metastases
  from colorectal cancer are the liver, the lungs, the inside of
  the abdomen, or the ovaries.

The next steps in treatment depend on the stage of the cancer. Most
colorectal cancers are first treated by some type of surgery.

• Small Stage 0 cancers may be completely removed during a colonoscopy.
  Some larger polyps can also be removed by inserting surgical
  instruments through the abdominal wall in a procedure called
  a laparoscopy.
• Stage I or Stage II cancers may be treated by removing the section
  of the colon that contains the tumor and then reconnecting the cut
  ends of the bowel. If reconnection is not possible, or if the cancer
  is at the lower end of the rectum, the doctor may have to perform a
  colostomy, in which an opening called a stoma is made in the wall
  of the abdomen and a portion of the remaining colon is attached
  to the stoma. The person’s body wastes pass through the stoma
  and are collected in a special bag attached to the outside of the
  body.
• If the cancer is advanced, surgery is unlikely to cure it. However,
  the surgeon can remove some of the tumor in order to relieve pain
  and bleeding.
  
• If the colorectal cancer has spread only to the liver and the
  patient’s health is otherwise good, the surgeon can remove the cancerous
  part of the liver with the colorectal tumor.

Radiation therapy or chemotherapy may be used following surgery
to lower the risk of recurrence. Chemotherapy is often used to treat
patients with Stage III or Stage IV cancer for a period of six to eight
months after surgery. Radiation therapy is used more often to treat Stage
III rectal cancer, although it may also be given to patients with colon
cancer to relieve pain or to shrink tumors before surgery.