The second step after the diagnosis of colon cancer is to check the stage of the condition. The course of treatment depends on the severity of the cancer. It is also influenced by whether or not it is a recurrence of the previously treated cancer, your general health, and the stage of colon cancer. Following the initial diagnosis, the doctor will assign a stage to your disease.

Let’s understand the stages of colon cancer 

Stage of colon cancer

1. Stage 0
This is the initial stage of colon cancer. It suggests that there’s a presence of cancer cells in the colon’s mucosa (innermost layer), which has not yet multiplied. This stage of colon cancer is known as carcinoma in situ. 

A polypectomy procedure is performed to help cure this stage. This treatment option helps eliminate all the malignant cells. When the cells affect the larger parts of the colon, the surgeon may perform an excision, a minimally invasive surgery, which takes place during the colonoscopy. 

2. Stage I
In this stage, the cancerous cells have already invaded the submucosa and the mucosa. The submucosa is the second layer of the colon. However, in this stage, the cancerous cells have still not entered the lymph nodes. 

To cure the cancer in Stage 1, partial colectomy (surgery) is performed in the affected area. The surgery involves re-fixing the colon parts that are still healthy. 

3. Stage II
In this stage, cancer has traveled beyond the colon wall. However, it has still not entered the lymph nodes. Stage II is further classified into three sub-stages: 

• Stage II A
  In this stage, cancer cells have not entered the surrounding tissues or the lymph nodes. Though it is present in the colon’s outer layers, it has not grown completely. 
• Stage II B
  In this, cancer has entered the serosa. However, cancer has still not affected the surrounding organs. 
• Stage II C
  In this stage, cancer cells have entered into the surrounding lymph nodes and have grown into the nearby structures or tissues. 

Surgery is mostly recommended to treat this stage of cancer. At times, chemotherapy may also be advised. 

4. Stage III
Stage III is also sub-divided into three stages.

• Stage III A
  Under this, the tumor has grown through or to the colon’s muscular layers and is present in the surrounding lymph nodes. However, cancer has not entered the distant organs or nodes.
• Stage III B
  In this, the tumor has traveled past the colon’s outermost layers and invades the other structures or organs. Herein, the cancer is present in one to three lymph nodes. Alternatively, the tumor may not travel across the colon’s outer layer but is present in more than three surrounding lymph nodes.
• Stage III C
  Under this, the tumor has already grown beyond the muscular layers and is present in over three lymph modes. However, it has still not traveled to distant sites.

Radiation and chemotherapy are the options to treat this stage of cancer.

5. Stage IV
It is the final stage of colon cancer. And this is the most critical stage as cancer cells have spread to the other body organs via lymph nodes and blood. The course of treatment in stages three and four is the same.