Colorectal Cancer

Treatment

Treatment for colon cancer varies, depending on the size and location of the tumor, among other factors. Surgery is the mainstay of therapy in most cases. Sometimes chemotherapy and/or radiation therapy may be recommended as well. Each patient typically is evaluted by a team of physicians. To better understand the specific characteristics of the tumor as well as "stage" of the cancer (extent to which it has spread), the doctors order a battery of diagnostic tests, including X-rays, CT scans, and blood tests. This evaluation will help the medical team design the best and most effective treatment regimen.

This section includes information on:

• Surgery
• Staging
• Chemotherapy
• Radiation therapy

Surgery

Surgery is the most common treatment for all stages of colon cancer. The surgeon may remove the cancer using one of the following procedures:

Colectomy: The surgeon may decide to cut out the part of the colon that contains the cancer as well as a small portion of surrounding normal tissue to get any stray cancer cells. Often, this is accomplished through a long incision in the abdominal wall.

Protectomy without colostomy: Some cancers require the surgical removal of large parts of the bowel. How much of the bowel is removed depends on a variety of factors, including the location of the tumor, the presence of other associated cancer or polyps, the stage of the cancer, and the risk of other colon cancers developing in the future.

The manner in which loops of the intestine are reconnected after the diseased portion is removed can vary. Some surgeons use sutures; others prefer using one of the various stapling techniques. Also, surgeons often take out lymph nodes near the colon to see if the cancer has spread. If the cancer does not appear to have invaded the lymph nodes and is completely removed during surgery, no further treatment may be needed.

When operating on rectal cancer, in the lowest part of the bowel, surgeons are using new techniques to spare surrounding tissue. Today, they often are able to leave intact nerves and sphincter muscles, preserving continence and sexual function. These innovative procedures have not only saved lives; they have greatly enhanced the quality of life for rectal cancer patients.

Protectomy with colostomy: If after resection the surgeon isn't able to reconnect the two ends of the colon, he or she may need to create a stoma, or small opening for wastes to pass through, in a procedure called a colostomy. Sometimes this procedure is later reversed, after the intestine has had time to heal. However, if much of the lower colon is removed, the colostomy will most likely be permanent.

Surgery for metastatic disease: In some cases, even when a cancer has already spread to other organs, surgical removal (resection) of these tumor deposits can be performed. This happens when the metastases are limited in number and sites.

The liver is the most common site of metastatic disease. Liver resection has been shown to prolong survival in many cases. When not removable, other techniques such as radiofrequency ablation, microwave ablation, or cryotherapy can be used.

Staging

Once colorectal cancer is detected, your physician will perform other tests to see whether it has spread. The tumor will be assigned a "stage" depending on the extent of the disease—the further along the stage, the more serious the cancer. In most cases, staging cannot be done until the cancer is removed and analyzed. The size of the tumor alone does not indicate its stage, so pathologists will analyze how deeply into the wall of the colon it extends and whether it has spread elsewhere in the body via the lymphatic vessels and blood vessels.

In some cases, a number of different tests are used to stage colorectal cancer prior to surgery. Some, including X-rays, CAT scans, and magnetic resonance imaging (MRI), are imaging tests to get a better picture of what's going on inside the body. Your doctor may also order laboratory tests to check the components of the blood and to look for carcinoembryonic antigen (CEA), a protein that may signal the presence of cancer.

Staging of colorectal cancer

Stage 0: Tumor is limited to inside of the lining of the colon or rectum.

Stage I: Tumor has invaded several layers of the colon or rectum but has not spread outside the wall.

Stage II: Cancer has grown through the wall of the colon or rectum and invaded nearby tissue, but has not spread to lymph nodes.

Stage III: Cancer has spread to nearby lymph nodes, but not to other parts of the body.

Stage IV: Cancer has spread to other organs and tissues such as the liver, lung, peritoneum, or ovary.

Chemotherapy

Chemotherapy uses drugs to stop the growth of cancer cells, either by killing them or by interfering with their division. This type of treatment may be given after surgery to attack cells that may have spread beyond the tumor (adjuvant therapy) or before surgery to shrink a tumor before removing it (neo-adjuvant therapy). Chemo is also used in cases where the cancer has spread.

The drugs are delivered in a variety of ways. When they are taken orally or injected into a vein, they travel throughout the body. This is called systemic chemotherapy. The drugs may also be placed into an organ or body cavity to deliver a more direct blow to a tumor.

There are two major kinds of chemotherapy: Cytotoxics, including 5-fluorouracil (5-FU), leucovorin, irinotecan (Camptosar), and oxaliplatin (Eloxatin), are small chemicals that interfere with basic cell division processes discovered long ago. The biologics are cetuximab (Erbitux), which targets the epidermal growth factor receptor (EGFR), and bevacizumab (Avastin), which targets vascular endothelial growth factor (VEGF). There are different schedules for receiving chemotherapy depending on the drugs being used.

Radiation therapy

Radiation therapy is typically used for rectal cancer and not for colon cancer. It kills cancer cells by bombarding them with high-energy X-rays. In external beam radiation therapy, a machine sends the X-rays through the skin to the diseased part of the rectum. Or a device may be inserted directly into the rectum to treat tumors; this procedure is called endocavitary therapy. Much less widely used in colorectal cancer is brachytherapy, a form of internal radiation therapy, where radioactive seeds are left in the affected area to treat the tumor.

Combining radiation therapy and chemotherapy after surgery is currently the standard of care for patients with Stage II or III rectal cancers. Patients with recurrent or advanced disease generally are offered radiation therapy to relieve symptoms and ease pain caused by the disease. In many cases, bulky primary cancers that can't be removed can be successfully controlled for a time with radiation therapy. Cancers that have spread from the rectum to the bone, brain, or pelvis have also been successfully controlled with radiation therapy.

In rectal cancer, combined radiation therapy and chemotherapy are increasingly being given pre-operatively to patients whose cancers have spread beyond the colon wall or to lymph nodes. This one-two punch often shrinks tumors, which gives surgeons a better shot at preserving the sphincter and, thus, bowel function.