The main stages of colon cancer can be understood once the initial diagnosis is done; staging is typically determined following some tests. Each of these tests is going to allow your doctor to identify the extent to which cancer has affected your body. Once he/she can determine the stage, he will prescribe the appropriate course of treatment.
The main stages of colon cancer are identified according to the TNM staging system devised by the American Joint Committee on Cancer. This system is going to take into account some factors like:
- The size of the original tumor and whether the cancer has penetrated the colon wall or into nearby parts.
- Penetration of the cancer cells in the nearby lymph nodes
- Chances of the cancer to metastasize and affect the other body parts like the liver and lungs
The following are the main stages of colon cancer:
1. Stage 0
This is the stage where abnormal cells will be discovered in the colon wall or mucosa and submucosa, and it is referred to as carcinoma in situ. Submucosa refers to the large intestinal underlining right under the mucosa and malignant cells in this stage can also penetrate deeper layers of this wall. But nothing has yet spread outside the colon. The treatment at this stage involves surgery for removing affected areas; so, a partial colectomy is performed and it focuses on rejoining colon parts that are still cancer-free and healthy.
2. Stage I
At this stage, cancer grows into inner colon layers or the mucosa but has not moved into lymph nodes.
3. Stage II
This is the stage where cancer has penetrated the colon wall, without affecting the lymph nodes. This stage has 3 substages:
- Stage IIA where cancer spreads to outer colon wall or serosa
- Stage IIB where it spreads past serosa but has not yet affected the nearby organs
- Stage IIC where cancer affects serosa and surrounding organs
When colon cancer is in the second stage, surgery is an option for removing the affected parts; chemotherapy may also be done in certain cases.
4. Stage III
In this stage, cancer has gone beyond colon lining and affected lymph nodes. Here, although lymph nodes have been affected, cancer is yet to reach other body organs. This can also be subdivided into 3 stages:
- Stage IIIA is where the tumor grows into the colon’s muscle layers and can be found in nearby lymph nodes.
- Stage IIIB is where the tumor penetrates to the muscular colon layers and moves into visceral peritoneum, invading other structures and organs, and can be detected in 1-3 lymph nodes.
- Stage IIIC is where the tumor has moved beyond muscular colon layers and found in 1-4 nearby lymph nodes.
Treatment options for all these above-mentioned main stages of colon cancer can be surgery to remove the affected areas, along with chemotherapy. Patients can also be prescribed radiation treatments if they are not strong enough to withstand surgery, or if they continue to have cancer cells even after surgery.
5. Stage IV
In this stage, cancer spreads to body organs through lymph nodes and blood. Patients will need to go through surgery to remove the small areas and organs affected by cancer; sometimes, very large affected areas have to be removed to save a life. Chemotherapy is done to shrink these tumors to make surgery more effective.