When an individual is diagnosed with colon cancer, the first task at hand for the doctor is to determine the stage of cancer. This is essential in deciding the action plan for the treatment procedures as various stages require various approaches. Each stage might have further subcategories to provide more information about the extent of the disease. Colon cancer is divided into 4 stages in the following way:

Stage 0: In this stage, cancer has not grown beyond the innermost layer of the colon or the mucosa. This is the earliest form of colon cancer.

Stage 1: In this stage, cancer has grown beyond the innermost layer of the colon or the mucosa. The affected cells have also spread to the inner layer of the colon, which is also called the submucosa. However, cancer has not extended to the lymph nodes at this stage.

Stage 2: This is a more severe stage of colon cancer. In this stage, cancer has spread beyond the mucosal layer and the submucosal layer of the colon. Based on how far the disease has spread, this stage is further categorized into three subcategories as follows:

• Stage 2A: This stage explains that cancer has not yet spread to the lymph nodes and has only expanded until the other layers of the colon. Even in the outer layers of the colon, at this stage, cancerous cells have not completely grown through.
• Stage 2B: Cancer has not yet spread to the lymph nodes by this stage but has grown through the complete outer layer and has also affected the visceral peritoneum. Visceral peritoneum is the organ responsible for holding the organs in the abdomen in their respective places.
• Stage 2C: The lymph nodes are not yet affected by cancer. It has, however, spread through the other layer of the colon and has begun its growth in the nearby structures or organs at this stage.

Stage 3:

• Stage 3A: Through the muscular layers of the colon, cancer has spread to lymph nodes near it. However, the nodes and organs distant to the colon are not yet affected at this stage.
• Stage 3B: Having grown through the outer layers of the colon, the visceral peritoneum, cancer invades other organs and structures along with one of the three lymph nodes. In some cases, cancer not having spread through the outer layers of the colon is present in 4 or more lymph nodes in the body.
• Stage 3C: Having grown through and beyond the muscular layers, at this stage, colon cancer is present in 4 or more lymph nodes but not distant organs.

Stage 4:

• Stage 4A: In this stage, cancer has also spread to one distant site like lungs or the liver.
• Stage 4B: This is the most advanced stage of colon cancer and indicates that cancer has spread to two or more distant sites/ organs.

Understanding the various stages of colon cancer can give the patients and their families an idea about the symptoms and treatment options for the stage, helping them cope with the situation better.