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Colon Cancer - Stages and Types of Colon Cancer

Home> Colon cancer> Overview and Types

What Is Colon Cancer?

The large intestine in humans is divided into the colon, rectum, and anus. The colon is the largest part of the large intestine. Various types of cells are present in the colon. Mutations in one or more cell types may result in uncontrolled growth and division. This condition involving uncontrolled growth and division of colon cells leading to tumor formation is known as colon cancer or colon carcinoma.

Although colon carcinoma may develop in people of any age, it most often occurs in the elderly. The initial stage of colon cancer is the formation of polyps. Although not all polyps turn into cancer, the presence of polyps significantly increases the risk of colon cancer. Men are at a higher risk of developing this condition than women.

How Common is Colon Cancer?

Colon carcinoma is slowly becoming one of the most prevalent cancers in India. The survival rates for this disease are relatively lower in India as compared to developed countries, and probable reasons for this include delayed diagnosis and limited access to better quality healthcare.

Also, another important aspect is that colon cancer incidence in India is likely under-reported due to underdiagnosis and limited access to healthcare in rural areas.

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What are the Different Types of Colon Cancer?

Based on the type of cell that it arises from, colon cancer is classified into various types. Different types of colon cancer include:

Most Common Types of Colon Cancer


Adenocarcinoma

Several glandular cells are present in the colon and produce mucus. The mucus is important for lubrication and protection of the internal wall of the colon. The cancer of these gland cells in the colon is known as colon adenocarcinoma. It is the most common type of colon carcinoma.

Squamous Cell Carcinoma

Squamous cell carcinoma arises from squamous cells, and it is exceptionally uncommon, as compared to other types of colon cancer.

Carcinoid Tumors

Carcinoid tumors are types of neuroendocrine tumors that are slow-growing. Carcinoid tumors usually do not cause any symptoms and are diagnosed incidentally. Due to their slow growth rate, they have very little potential to metastasize. In many cases, there will be more than one carcinoid tumor.

Lymphoma

Colon lymphoma, or colonic lymphoma, is one of the relatively rare types of colon cancer, and it arises from the lymphatic system in the colon. Non-Hodgkin lymphoma is a more common form of colonic lymphoma.


Rare Types of Colon Cancer


Gastrointestinal Stromal Tumors (GIST)

These rare lesions in the colon occur due to the formation of abnormal cells in the tissues of the colon. The risk of gastrointestinal stromal tumors is increased by certain genetic factors. The symptoms of gastrointestinal stromal tumors include vomiting and blood in the stool. GISTs often begin as benign tumors and later become cancerous.

Leiomyosarcomas

Leiomyosarcoma of the colon is an extremely invasive and rare tumor. The tumor develops in the muscularis propria, which is the smooth muscle layer of the gastrointestinal tract.

Melanomas

Melanomas of the colon are exceptionally rare. Melanoma is a type of skin cancer that can rarely metastasize into the colon. In exceedingly rare cases, melanoma-causing cancer cells (cancerous melanocytes) develop in the colon, and such cases are termed primary colonic melanoma.

What are the Stages of Colon Cancer?

Following are the colon cancer stages:

Stage 0 Colon Cancer

This stage is known as cancer in situ. The cancerous cells are present only in the inner lining of the colon, or mucosa.

Stage 1 Colon Cancer

Cancer develops in the mucosa and muscular layers of the colon. No cancer growth occurs in the nearby lymph nodes or tissues.

Stage 2 Colon Cancer

The cancer invades the wall of the colon, the muscle of the abdominal lining (visceral peritoneum), or the wall of the colon and nearby structures but does not spread to nearby lymph nodes.

Stage 3 Colon Cancer

The cancer has grown to the inner muscular lining with 1 to 3 lymph nodes, or the bowel wall or surrounding organs with 1 to 3 lymph nodes, or ≥ 4 lymph nodes, irrespective of the depth of cancer growth.

Stage 4 Colon Cancer

Cancer has spread to only one distant site, such as the lungs or liver, or to more than one distant site, or to the peritoneum, with or without invading distant organs.


Conclusion


Colon carcinoma occurs in the colon and is one of the most common cancers globally. There are various types of colon cancer. The most common are squamous cell carcinoma, lymphoma, adenocarcinoma, and carcinoid tumors.


Colon carcinoma is categorized into various stages depending on the extent of the disease’s spread. Early-stage cancers have a better prognosis than those in advanced stages.

Frequently Asked Questions

What is type 4 colon cancer?

"Type 4 colon cancer" is not considered a standard term in the staging or classification of colon cancer. The stage of cancer is typically indicated by a numerical stage (e.g., stage 0, stage I, stage II, stage III, stage IV), where cancers of stages 0, 1, and 2 refer to early-stage colon carcinoma, and stages 3 and 4 refer to advanced-stage colon carcinoma.

In the early stages of colon carcinoma, only the colon is affected. However, as the disease progresses, it may spread to nearby lymph nodes and organs, such as the lungs, liver, and digestive tract organs.

Stage 4 colon cancer refers to the end stage of the disease when cancer spreads to one or more distant organs, e.g., the lungs and liver.

Yes, cancer of the colon affects the intestine and other parts of the digestive tract, such as the rectum.

Life expectancy after colon carcinoma depends upon the stage at diagnosis, the patient's overall health, and the treatment response. For instance, early-stage or stage 1 and 2 colon cancer patients have a better prognosis than stage 4 colon cancer.

Usually, if there is no recurrence of colon cancer after five years of treatment, the patient is considered cancer-free. That said, the patient can still be at risk of a recurrence; therefore, they should be put on proper follow-up care.

There are different types of colon cancer, depending on the cell type from which it arises. Colon cancer arising from gland cells is called adenocarcinoma; if it arises from neuroendocrine cells, it is called a carcinoid tumor; and lastly, if it originates from the lymphatic system, it is called colonic lymphoma.

Some patients may have recurrences after colon carcinoma treatment completion. That said, a proper follow-up regime after the treatment can help catch recurrences in their early stages, when they are managed best.

Yes, they are treatable. However, the quality of clinical outcomes depends on the stage of diagnosis, response to treatment, overall health of the patients, and cancer complications. Those patients who are in the early stages of colon cancer have a relatively favorable prognosis.

Inadequate physical activity, a poor diet, and a sedentary lifestyle are the major causes of this condition in young adults.

There is no method to prevent this condition. However, certain measures, such as exercising, eating healthy, and quitting smoking, can help reduce its risk.