Staging and Evaluation
The diagnosis of colorectal cancer is most often made after colonoscopy and tumor biopsy by a pathologist. The main goal at the Siteman Cancer Center is to get a correct diagnosis of your cancer, often down to the genetic level so the best treatment options may be identified.
Treatment Options and Prognosis
Determining the most effective treatments and measuring the chances of recovery depend on the following:
- The stage of the cancer (whether the cancer is in the inner lining of the colon only or has spread through the colon wall, or has spread to lymph nodes or other places in the body).
- Whether the cancer has blocked or made a hole in the colon.
- Whether there are any cancer cells left after surgery.
- Whether the cancer has recurred.
- The patient’s general health.
There are three ways that cancer spreads in the body:
- Through tissue by growing into nearby areas.
- Through the lymph system, traveling to other parts of the body.
- In the bloodstream, going to other parts of the body.
Metastasis occurs when cancer spreads to another part of the body. The metastatic tumor is the same type of cancer as the primary tumor. For example, if colon cancer spreads to the bone, the cancer cells in the bone are actually colon cancer cells. The disease is metastatic colon cancer, not bone cancer.
Tests Used in the Staging Process Include the Following
CT scan (computerized tomography): The pictures are made by a computer linked to an X-ray machine. A dye may be injected into a vein or swallowed to help the organs or tissues show up more clearly. This test is used to check for the spread of the cancer to the lungs, liver and lymph nodes.
MRI (magnetic resonance imaging): This imaging form uses a magnet, radio waves, and a computer to make a series of detailed pictures of areas inside the colon. A dye may be injected into the patient through a vein to the cancer cells so they show up brighter in the picture. The test can also be used to evaluate the liver and the thickness and lymph node spread of a rectal cancer.
PET scan (positron emission tomography): This imaging looks for malignant tumor cells in the body. A small amount of radioactive glucose (sugar) is injected into a vein. The PET scanner rotates around the body and makes a picture of where glucose is being used in the body. Malignant tumor cells show up brighter in the picture because they are more active and take up more glucose than normal cells do. This test is most often used to look for the return of a colorectal cancer in the body or to monitor response to treatment.
Rigid proctoscopy and endorectal ultrasound for rectal cancers: The surgeon inserts a scope into the rectum to determine the exact location of a rectal cancer. The Ultrasound probe is inserted into the rectum to determine the thickness of the cancer and whether lymph nodes are involved.
Pelvic MRI for rectal cancers: to determine T stage (depth of tumor invasion into the wall of the rectum), N stage (lymph node involvement) and proximity of the tumor to the resection margin or other structures in the pelvis.
Stages of Colorectal Cancer
Stage 0 (carcinoma in situ): In stage 0, abnormal cells are found only in the mucosa (inner wall) of the bowel.
Stage I: Cancer has spread from the mucosa of the colon wall into the muscle layer.
Stage 2 is divided into stages 2A, 2B and 2C.
Stage 2A colon cancer: Cancer has spread through the muscle layer of the colon wall to the serosa (outermost layer) of the colon wall.
Stage 2B: Cancer has spread through the serosa of the colon wall but has not spread to nearby organs.
Stage 2C: Cancer has spread through the serosa of the colon wall to nearby organs.
Stage 3 colon cancer is divided into 3A, 3B and 3C
Stage 3A: Either cancer has spread through the mucosa of the colon wall to the submucosa and perhaps to the muscle layer, and has spread to 1-3 nearby lymph nodes or tissues near the lymph nodes; or cancer has spread through the mucosa to the submucosa and four to six nearby lymph nodes.
Stage 3B: There are five types of Stage 3B: (1) Cancer has spread through the muscle layer of the colon wall to the serosa or has spread through the serosa but not to nearby organs; (2) cancer has spread to one to three nearby lymph nodes or to tissues near the lymph nodes; (3) cancer has spread to the muscle layer or to the serosa, and to four to six nearby lymph nodes; (4) cancer has spread through the mucosa to the submucosa and may have spread to the muscle layer; or (5) cancer has spread to seven or more nearby lymph nodes.
Stage 3C: Again, there are multiple possible configurations: (1) Cancer has spread through the serosa of the colon wall but not to nearby organs; (2) cancer has spread to four to six nearby lymph nodes; (3) cancer has spread through the muscle layer to the serosa or has spread through the serosa but not to nearby organs; (4) cancer has spread to seven or more nearby lymph nodes; or (5) cancer has spread through the serosa to nearby organs and to one or more nearby lymph nodes or to tissues near the lymph nodes.
Stage 4 colon cancer: The cancer has spread through the blood and lymph nodes to other parts of the body, such as the lung, liver, abdominal wall or ovary. Stage 4 colon cancer is divided into stage 4A and stage 4B.
Stage 4A: Cancer may have spread through the colon wall and may have spread to nearby organs or lymph nodes. Cancer has spread to one organ that is not near the colon, such as the liver, lung, or ovary or to a distant lymph node.
Stage 4B: Cancer may have spread through the colon wall and may have spread to nearby organs or lymph nodes. Cancer has spread to more than one organ that is not near the colon or into the lining of the abdominal wall.
Recurrent Colon Cancer: This is cancer that has come back after it has been treated. The cancer may come back in the colon or in other parts of the body, such as the liver, lungs, or both.
Depending on the diagnosis and staging of the colon cancer, physicians may consult the National Comprehensive Cancer Network (NCCN) guidelines, which Siteman physicians helped develop, for standard of treatment, to which might be added promising treatments from clinical trials.