Colon cancer and rectal cancer are frequently grouped together because they have many features in common. Colorectal cancer can start in the colon or the rectum, and depending on where it starts, these cancers can also be called colon cancer or rectal cancer.
Understanding the Digestive System
The large intestine, also known as the large bowel, is made up of the colon and rectum and is a component of the digestive system.
The colon, a muscular tube that is roughly 5 feet (1.5 meters) in length, makes up the majority of the large intestine. The names of the colonic sections reflect the direction in which food passes through them.
- The ascending colon is the name of the first part. Undigested food enters through a pouch called the cecum at the beginning of the digestive process. On the right side of the abdomen, it goes higher (belly).
- The transverse colon is the second segment. It crosses the body from side to side, right to left.
- Due to the fact that the third part descends (moves down) on the left, it is known as the descending colon.
- Because of its “S” form, the fourth portion is referred to as the sigmoid colon. The rectum attaches to the anus after the sigmoid colon does.
What Causes Colorectal Cancer?
Most colorectal cancers begin as polyps, which are growths on the rectum or colon’s inner lining. The ascending and transverse regions are collectively referred to as the proximal colon, while the descending and sigmoid sections are referred to as the distal colon.
While not all polyps develop into cancer, some can do so over time (often, after many years). Its likelihood to progress to cancer depends on its type. There are various kinds of polyps.
- Adenomatous polyps (adenomas): Adenomas, which come in three different varieties (tubular, villous, and tubulovillous), are regarded as precancerous conditions since they can occasionally develop into cancer.
- Hyperplastic polyps and inflammatory polyps: Although they are more frequent, these polyps are typically not precancerous. Large (greater than 1 cm) hyperplastic polyps may necessitate more frequent colonoscopies for colorectal cancer screening.
- Sessile serrated polyps (SSP) and traditional serrated adenomas (TSA): As a result of their increased risk of colorectal cancer, these polyps are frequently treated like adenomas.
Other factors that could raise a person’s chances of developing colorectal cancer or make a polyp more likely to contain cancer include:
- A polyp larger than 1 cm is found
- The presence of more than 3 polyps
- Dysplasia is another precancerous disease that indicates there is a region in a polyp or in the lining of the colon or rectum where the cells appear abnormal but have not yet developed into cancer. Dysplasia is found in the polyp after it has been removed.
- Colorectal cancer begins in the innermost layer (the mucosa) of the colon or rectum and can spread outward through some or all of the other layers over time if it develops in a polyp. The wall of the colon or rectum is made up of multiple layers.
Once cancer cells have penetrated the wall, they may continue to proliferate and spread to neighboring lymph nodes or blood arteries, which are microscopic passageways that remove waste and fluid.
The depth to which colorectal cancer grows into the wall and whether it has spread outside the colon or rectum determine the stage, or extent of the disease.
Types of Colon Cancer And Rectal Cancer
When clinicians talk about colorectal cancer, they almost always refer to adenocarcinomas, which are the most common kind. Some subtypes of adenocarcinomas, such as signet ring and mucinous, may have a worse prognosis than other subtypes of adenocarcinoma.
- Carcinoid tumors. These originate in the intestine from distinct hormone-producing cells.
- Gastrointestinal stromal tumors (GISTs) start from special cells in the wall of the colon called the interstitial cells of Cajal. Some are benign (not cancer). These tumors can be found anywhere in the digestive tract, but are not common in the colon.
- Lymphomas are cancers of immune system cells. They mostly start in lymph nodes, but they can also start in the colon, rectum, or other organs. Information on lymphomas of the digestive system can be found in Non-Hodgkin Lymphoma.
- Sarcomas can start in blood vessels, muscle layers, or other connective tissues in the wall of the colon and rectum. Sarcomas of the colon or rectum are rare.
The 5 Stages of Colon Cancer
The severity of the condition is indicated by a number and letter allocated to each of the three types of colon cancer based on the structure of the colon and how far the disease has spread through the layers of the colon wall.
The stages of colon cancer are as follows:
Stage 0
Stage 0 colon cancer means that the disease has not progressed past the mucosa, the innermost layer of the colon.
Stage 1
In stage 1 colon cancer, the disease has advanced to a muscle layer called the muscularis propria as well as from the uppermost layer, known as the mucosa, to the next layer, known as the submucosa.
Stage 2
Compared to stage 1, stage 2 colon cancer is a little more advanced and has spread past the mucosa and submucosa.
- Stage 2A, 2B, or stage 2C are additional classifications for stage 2 colon cancer.
- Phase 2A. Lymph nodes or adjacent tissue have not been affected by the cancer’s spread. Although it has gotten into the colon’s outermost layers, it hasn’t fully penetrated.
- Level 2B. The visceral peritoneum, which is the membrane holding the abdominal organs in place, has been invaded by cancer, which has not yet progressed to the lymph nodes but has grown through the outer layer of the colon.
- 2C stage. Although cancer has not yet migrated to the lymph nodes, it has already penetrated the colon’s outer layer and other surrounding organs or structures.
Stage 3
There are three possible stages of stage 3 colon cancer: 3A, 3B, and 3C.
- Stage 3A. The tumor has reached or passed through the muscular layers of the colon, and nearby lymph nodes have noticed it.
- Stage 3B. In one of the following situations, colon cancer will be considered to be in stage 3B: The tumor has invaded the visceral peritoneum, the outermost layers of the colon, and into other organs or tissues. It is also present in one to three lymph nodes. Although the tumor has not reached the colon’s outermost layers, it can be found in four or more nearby lymph nodes.
- Stage 3C. The tumor has spread beyond the muscle layers. Nevertheless, cancer is not found in remote areas; it is also seen in four or more surrounding lymph nodes.
Stage 4
Stage 4 colon cancer can be stage 4A, stage 4B, or stage 4C.
- Stage 4A. The cancer has spread to a single distant site, such as the liver, lungs, or lymph nodes, at this stage.
- Stage 4B. Despite not reaching the peritoneum, cancer has progressed to two or more distant sites.
- Stage 4C. There is a cancerous infection in the peritoneum.
Colon Cancer FAQs
Here are some frequently asked questions about this form of cancer:
A personal or family history of colorectal cancer or polyps increases a person’s risk of developing the disease. Men and women 50 years of age and beyond are almost equally at risk of developing colorectal cancer. A larger risk applies to anyone who has a long personal history of inflammatory bowel illness.
How common is colorectal cancer?
Currently, colorectal cancer is the third most common site of malignancy in the Philippines. From 2010 to 2015, the number of cases escalated from 5,787 to 9,625.
Colorectal cancer is the second most common cancer in the United States. More than 56,000 Americans die from colorectal cancer, with more than 140,000 new cases diagnosed. More women over 75 die from colorectal cancer than from breast cancer, and 80 to 90 million Americans are thought to be at risk due to age or other factors.
How long does colon cancer take to develop?
Once cancer has developed in the colon, its progression will vary depending on the cellular make-up of the tumor and other factors, such as the patient’s age and general health. While the majority of these polyps will not develop into cancer, some can slowly transform into cancer over the course of about 10-15 years.
Can stage 4 colon cancer be survived for 10 years?
The 5-year survival rate for colon cancer is 91% when it is discovered at a localized stage; it is 72% when it has spread to nearby tissues or organs or local lymph nodes and it is 14% when it has reached distant sections of the body. For a period of 10 years, the survival rate is 2% or less.
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