Overview on Stages of Colon Cancer.
The term “stage” means the description of the extent of a certain type of cancer in the body. It’s one of the most crucial factors in deciding the breast treatment option and in expecting the outcome of every single case.
Clinically, we stage colon cancer depending on different diagnostic methods; such as physical exam, biopsy of cancer itself, CT scan, MRI scan, and other diagnostic modalities.
There are two ways to stage colon cancer:
- The clinical based staging which depends on the doctor’s examination, the biopsy from cancer, and other imaging modalities.
- The pathologic staging which depends on the surgical appearance of cancer in addition to the clinical based staging.
What is colon cancer staging (TNM system)?
The standard staging system for colon cancer is named the TNM system. In this system, we use certain letters and numbers to give certain piece of information. The “TNM” stands for:
- T stands for Tumor: The extension of spread of the tumor itself within the wall of the colon.
- N stands for Nodes: The possible extension of cancer into the lymph nodes.
- M stands for Metastasis: Which is the extension of the tumor into other parts in the human body.
The numbers which are written after the T,N,M indicate the severity while the letter X after T, N, M indicate that we can’t assess this part.
What is T staging of Colon Cancer?
- TX stands for the inconclusive information about the extension of the tumor.
- TIS stand for the inner layer of the colon which is known as mucosa; this is pathologically named as carcinoma in situ.
- T0 stands for no cancer in any layer of the colon.
- T1-T4 stands for the extension of caner into different layers of the colon; from the most inner to the most outer.
What is N staging of Colon Cancer?
- NX stands for the inconclusive information about the involvement of lymph nodes.
- N0 stands for no involvement of the lymph nodes.
- N1 stands for the involvement of the lymph nodes, not more than three lymph nodes.
- N2 stands for the involvement of the lymph nodes, more than four lymph nodes.
What is M staging of Colon Cancer?
- MX stands for the inconclusive information about the involvement of distant organs.
- M0 stands for no involvement in the distant organs.
- M1 stands for the involvement of the distant organs.
How is grouping of TNM data done?
After we determine the value of T, N, M, we group the data into large groups numbered from stage 0 to stage IV. Following are the details:
- Stage 0:
This stage is the earliest one; cancer still in the innermost layer of the colon and there is no lymph nodes neither distant organs involvement. That’s TIS, N0, and M0. This stage is usually treated with simple surgery and it has a very excellent prognosis.
- Stage I:
In this stage, cancer expands beyond the inner layer of the colon to reach the fibrous layer; which is known as submucosa or even the deeper layer of the muscles but don’t reach the lymph nodes neither the distant organs. That’s T1 or T2 with N0 and M0. This stage is treated via surgical resection and it has a very good prognosis.
- Stage II:
Cancer has implanted deeply into the wall of the colon and exceeds the muscular layer but it doesn’t reach the lymph nodes or the distant organs yet. That’s T3 or T4 but N0 and M0. This stage is treated with surgery as well but the patient may undergo a course of radiotherapy or chemotherapy depending on the doctor recommendation. The prognosis is not that good as stage I but it’s still better than stage III.
- Stage III:
In this stage, regardless of the T value; the extension of tumor into the colon wall, there is an involvement of the lymph nodes but not the distant organs. That’s T1-T4, N1 or N2, but M0. The treatment of this stage depends on the doctor decision; the surgical option is still available and effective but the patient needs to take some radiotherapy or chemotherapy to treat the involved lymph nodes. The prognosis is generally good but not as the previous stages.
- Stage IV:
In stage IV, regardless of the tumor extension in the wall of the colon and regardless of the lymph nodes involvement, cancer spreads to the distant organs. That’s T1-T4, N0-N2, but M1. Colon cancer can spread anywhere in the body but most likely it will spread to the liver, lung, bone, and brain. Unfortunately, this is a very late stage and the curative surgical option is not available. Usually, those patients undergo multiple intensive sessions of radiotherapy and/or chemotherapy. The prognosis, in general, is poor. The five years survival rate is very low.
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Colon cancer is a very common type of cancer worldwide. It’s one of the leading causes of death worldwide. Once we diagnose colon cancer, staging process is essential to guide the treatment plan. Staging of colon cancer depends on three components; the extent of cancer spread within the colon wall (T), the involvement of lymph nodes (N), and the involvement of distant organs (M).
The staging process of colon cancer depends on the surgical resection of the involved part of the colon with sampling of the surrounding lymph nodes, in addition to the other diagnostic and imaging modalities; mainly the CT scan, MRI scan, bone scan and other tests. Colon cancer produces no symptoms until it spreads all around the body.
That’s why screening and early detection is very crucial for the survival of the patient. The early the diagnosis, the better the outcome; survival rates in early stages; especially stage I and II, is very high in comparison with stage III. Stage IV owns the worst prognosis among all the other stages.
Many screening tests are available; it’s very important to consult your doctor about the best test and time to do them. Regular screening leading to early detection is the key to survive colon cancer.