How are colon cancer stages assessed?

Posted by Master, Doctor Mai Vien Phuong - Department of Examination & Internal Medicine - Vinmec Central Park International General Hospital

If you're diagnosed with colon cancer, one of the first things your doctor wants to determine is the stage of your cancer. Staging refers to how far the cancer has spread and helps find the best treatment.

Colon cancer is often staged based on a system established by the American Joint Committee on Cancer called the TNM staging system.
The system considers the following:
Primary tumor (T): Primary tumor refers to how large the original tumor is and whether the cancer has grown into the wall of the colon or spread to other organs. neighborhood or not. Regional lymph nodes (N): Regional lymph nodes refer to whether cancer cells have spread to nearby lymph nodes. Distant metastasis (M): Distant metastasis refers to cancer that has spread from the colon to other parts of the body, such as the lungs or liver.

Within each category, the disease is further classified and assigned a number or a letter to indicate the extent of the disease. These indications are based on the structure of the colon, as well as the extent to which the cancer has grown through the layers of the colon wall. The stages of colon cancer are as follows:

This is the earliest stage of colon cancer and means it has not grown beyond the lining or innermost layer of the colon.

Stage 1 colon cancer indicates the cancer has grown into the inner layer of the colon, called the mucosa, to the next layer of the colon, called the submucosa. It has not spread to the lymph nodes.

In stage 2 colon cancer, the disease is slightly more advanced than in stage 1 and has grown beyond the mucosa and submucosa of the colon.
Stage 2 colon cancer is further classified as stage 2A, 2B or 2C:
Stage 2A : The cancer has not spread to nearby lymph nodes or tissues. It has reached the outer layers of the colon but has not fully developed. Stage 2B: The cancer has not spread to the lymph nodes, but has grown through the outer layer of the colon and into the visceral peritoneum. This is the membrane that holds the organs in the abdomen. Stage 2C: The cancer has not been found in nearby lymph nodes, but in addition to growing through the outer layer of the colon, it has grown to nearby organs or structures.

Stage 3 colon cancer is classified into stages 3A, 3B and 3C:
Stage 3A : The tumor has grown to or through the muscular layers of the colon and is found in nearby lymph nodes there. It has not yet spread to distant nodes or organs. Stage 3B: The tumor has grown through the outermost layers of the colon and through the visceral peritoneum or invaded other organs or structures, and is found in 1 to 3 lymph nodes. Or the tumor has not penetrated the outer layers of the colon wall but is found in 4 or more nearby lymph nodes. Stage 3C: The tumor has grown beyond the muscle layers and cancer is found in 4 or more nearby lymph nodes, but not distant sites.

Stage 4 colon cancer is classified into two types, stages 4A and 4B:
Stage 4A : This stage shows that the cancer has spread to a distant site, such as the liver or lungs. Stage 4B: The most advanced stage of this colon cancer shows that the cancer has spread to two or more distant sites, such as the lungs and liver.

In addition to staging, colon cancer is also classified as low-grade or high-grade.
When a pathologist examines cancer cells under a microscope, they assign a number from 1 to 4 based on how much it looks like healthy cells.
The higher the grade, the more abnormal the cells look. Although they can vary, low-grade cancers tend to grow more slowly than high-grade cancers. The prognosis is also considered better for people with low-grade colon cancer.

In the early stages of colon cancer, there are usually no signs or symptoms. In the later stages, symptoms tend to vary based on the size and location of the tumor in your large intestine. These symptoms may include:
Change in bowel habits Blood in stools or rectal bleeding Abdominal pain Fatigue Unexplained weight loss

There are 4 screening options for colorectal cancer:
Fecal immunochemical testing (FIT) every year FIT every 2 years Pelvicoscopy sigmoidoscopy Whole colonoscopy According to the American College of Physicians, colonoscopy is the standard test for colon cancer. However, if for some reason you are not a good candidate for a colonoscopy, they recommend both the FIT test and a colonoscopy.
If after a FIT test or colonoscopy you are positive for colorectal cancer, your healthcare provider will recommend a colonoscopy to confirm your diagnosis .
A colonoscopy is an examination where your doctor uses a long, narrow tube with a small camera attached to it to see the inside of your colon.
If colon cancer is detected, additional tests are often needed to determine the size of the tumor and whether it has spread outside the colon.
Diagnostic tests performed may include imaging of the abdomen, liver, and chest with a CT scan, X-ray, or MRI scan.
There may be cases where it is not possible to fully determine the stage of the disease until colon surgery is performed. After surgery, the pathologist can examine the primary tumor along with the removed lymph nodes, helping to determine the stage of the disease.

The recommended treatment for colon cancer largely depends on the stage of the disease. Remember, treatment will also take into account the type of cancer, your age, and your overall health.
According to the American Cancer Society, typically each stage of colon cancer is treated in the following ways:
Stage 0 : Surgery is often the only treatment needed for advanced colon cancer. stage 0.
Stage 1: Surgery is recommended only for stage 1 colon cancer. The technique used may vary based on the location and size of the tumor.
Stage 2: Surgery is recommended to remove the cancerous part of the colon and nearby lymph nodes. Chemotherapy may be recommended in certain cases, such as if the cancer is considered high-grade or if high-risk features are present.
Stage 3: Treatment includes surgical removal of the tumor and lymph nodes followed by chemotherapy. In some cases, radiation therapy may also be recommended.
Stage 4: Treatment may include surgery, chemotherapy and possibly radiation. In some cases, targeted therapy or immunotherapy may also be recommended.
Conclusion
The stage of colon cancer affects the way you look. People diagnosed with stage 1 and 2 colon cancers often have the highest survival rates.
Remember, colon cancer stage is not the only thing that determines survival rates. It's important to understand that many factors will affect your outlook, including how well you respond to treatment, your age, the extent of your cancer, and your overall health at the time of diagnosis. .
At Vinmec International General Hospital with a team of leading doctors and nurses with rich experience in the field of colorectal cancer diagnosis and treatment, with the support of a system of modern and fully equipped technology equipment. enough professional facilities to diagnose the disease and stage it before treatment such as: Endoscopy, CT scan, PET-CT scan, MRI, Mammogram, histopathological diagnosis, genetic testing - cells, ... help detect colon cancer early even when there are no symptoms.

The article references the source: Colon and rectum cancer staging. (2009). Qaseem A, et al. (2019). Screening for colorectal cancer in asymptomatic average-risk adults: A guidance statement from the American college of physicians. Treatment of colon cancer, by stage. (2020).