Colorectal Cancer Stage III

Stage III colorectal cancer has spread into nearby lymph nodes, but has not reached other areas of the body. With treatment involving surgery and often chemotherapy, many patients can be cured.

Table of contents

• What is Stage III Colorectal Cancer?
• Subcategories of Stage III
• Treatment Options
• Prognosis and Outcomes

What is Stage III Colorectal Cancer?

Stage III colorectal cancer occurs when cancer has spread through the wall of the colon or rectum into nearby lymph nodes, which are small structures that help fight infection. At this stage, the cancer has not yet spread to distant parts of the body such as the liver or lungs.^[1]

Colorectal cancer develops in the colon, which is the main part of the large intestine and is about 5 feet long, or in the rectum, which is the last part of the large intestine before the anus.^[12] The cancer starts in the innermost layer of the intestine and can grow through multiple layers of tissue.

Subcategories of Stage III

Stage III colorectal cancer is divided into three subcategories based on how deeply the cancer has grown through the bowel wall and how many lymph nodes contain cancer.^[1]

Stage IIIA

In Stage IIIA, the cancer has spread through the innermost layer of the colon wall, called the mucosa, to the layer next to it, called the submucosa, or to the muscle layer of the colon wall. It has also spread into one to three nearby lymph nodes or into tissue near the lymph nodes.^[1]

Alternatively, Stage IIIA can mean the cancer has spread through the mucosa to the submucosa and has also spread to four to six nearby lymph nodes.^[2]

Stage IIIB

Stage IIIB means one of several possibilities. The cancer has spread through the muscle layer of the colon wall to the outermost layer, called the serosa, or has spread through the outermost layer to the tissue that wraps around the organs in the abdomen, and it has spread to between one and three nearby lymph nodes or to areas of fat close to the lymph nodes.^[1]

Stage IIIB can also mean the cancer has grown into the muscle or outer lining of the bowel wall and between four to six nearby lymph nodes contain cancer. Another possibility is that the cancer is still in the inner or muscle layer of the bowel wall but it has spread to seven or more nearby lymph nodes.^[2]

Stage IIIC

Stage IIIC is the most advanced form of Stage III cancer. It can mean the cancer has grown through the outer lining of the bowel wall into the tissue layer covering the organs in the abdomen and between four to six nearby lymph nodes contain cancer.^[2]

It can also mean the cancer has grown into the outer lining of the bowel wall or into the tissue layer covering the organs in the abdomen and it has spread to seven or more nearby lymph nodes. Another possibility is that the cancer has grown through the bowel wall into other nearby organs and it has spread to at least one nearby lymph node or to areas of fat close to the lymph nodes.^[2]

Treatment Options

Surgery

Surgery is the main treatment for Stage III colon cancer. The procedure usually involves a bowel resection with a lymph node dissection. During this surgery, the surgeon removes the section of colon containing the cancer along with nearby lymph nodes. The type of bowel resection depends on where the tumor is located.^[13]

After the bowel resection, some patients may need a temporary or permanent colostomy or ileostomy. A colostomy creates an opening from the colon to the outside of the body through the abdominal wall, while an ileostomy creates an opening from the ileum to the outside of the body. These procedures create a new path for stool to leave the body. A temporary colostomy or ileostomy may be needed to allow the intestine to rest and heal after surgery.^[13]

Chemotherapy

Adjuvant chemotherapy is treatment given after surgery to reduce the risk of cancer coming back. For Stage III colon cancer, adjuvant chemotherapy has been shown to reduce the risk of tumor relapse and improve survival.^[11]

The most common chemotherapy approach combines a drug called oxaliplatin (brand name Eloxatin) with 5-fluorouracil and leucovorin. These combinations may be abbreviated as FOLFOX or CAPOX, depending on exactly how the drugs are given.^[6]

Adding oxaliplatin to standard chemotherapy appears to improve outcomes. In clinical trials comparing patients receiving standard chemotherapy alone versus standard chemotherapy plus oxaliplatin, those receiving oxaliplatin had better three-year disease-free survival rates, with improvements of 5 to 7 percent.^[6]

Another option is capecitabine (brand name Xeloda), which is a form of 5-fluorouracil given as a pill rather than through a vein. This oral form is more convenient since it requires fewer clinic visits.^[6]

Treatment Duration

The duration of chemotherapy treatment can be reduced from six months to three months in certain situations, depending on the specific chemotherapy regimen and the patient’s risk level. This shorter treatment duration can significantly reduce side effects, especially cumulative sensitive neuropathy (nerve damage that causes numbness or tingling), while maintaining effectiveness.^[11]

Treatment for Rectal Cancer

For Stage III rectal cancer (cancer in the back passage), treatment options may include surgery, radiation therapy, chemotherapy, or a combination called chemoradiotherapy. Some patients may have a short course of radiotherapy followed by surgery, while others may have chemoradiotherapy followed by surgery. Your doctor might also offer chemotherapy after surgery if tests show there is a high risk of the cancer coming back.^[2]

Prognosis and Outcomes

Stage III colon cancer is considered curable for many patients. Depending on the specific features of the cancer, approximately 40 to 50 percent of patients are cured with no evidence of cancer recurrence following treatment with surgery alone.^[6]

However, despite complete surgical removal of the cancer, about half of patients with Stage III colon cancer experience recurrence. This is due to the presence of small amounts of cancer that have spread outside the colon, called micrometastases. These cancer cells cannot be detected with currently available tests, which is why chemotherapy after surgery is important to eliminate these hidden cancer cells and improve cure rates.^[6]

In clinical trials, adding oxaliplatin to standard chemotherapy resulted in three-year disease-free survival rates of 72 to 76 percent, compared with 65 to 72 percent with standard chemotherapy alone.^[6] Research shows that only about 30 percent of patients will actually benefit from adjuvant treatment, with 50 percent already cured by surgery alone and 20 percent experiencing disease recurrence despite treatment.^[11]