The vast majority of colorectal cancers are adenocarcinomas. There are also some rarer types that may have different symptoms, treatments, and outlooks.
Colorectal cancer is cancer that develops in the colon or rectum.
This article gives an overview of the most and least common types of colorectal cancer and answers some frequently asked questions.
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Adenocarcinomas are cancers that start in the cells that produce mucus, which lubricates the inside of the rectum and colon. They are the most common type of colorectal cancer, accounting for around
They can develop from benign tumors called adenomas or pre-cancerous growths called adenomatous polyps. Although they are typically slow growing, they can eventually spread to other areas of the body.
These cancers can cause different symptoms depending on their location within the colon. Most colorectal adenocarcinomas develop on the left side of the colon, where the bowel channel narrows. As the cancer grows, it can constrict the bowel channel, causing a partial intestinal blockage.
Symptoms may include:
- a change in bowel habits
- constipation
- narrow, ribbon-shaped stool if the cancer is low in the rectum
Right-sided colorectal adenocarcinomas are less common. A large tumor may cause the following symptoms:
- pain
- chronic blood loss
- anemia
Learn more about colorectal cancer.
Treatment and outlook
The treatment for this type of cancer depends partly on the stage. Treatment approaches may include:
- surgery
- chemotherapy
- radiation therapy
- targeted therapy
- immunotherapy
Adenocarcinomas make up the vast majority of colon cancers. The 5-year relative survival rate for all types of colon cancer is
| Stage | 5-year relative survival rate |
|---|---|
| Localized, meaning it has not spread beyond the colon or rectum | 91% |
| Regional, meaning it has spread to nearby lymph nodes and other structures | 73% |
| Distant, meaning it has spread to distant organs and tissues | 13% |
The relative survival rate suggests how long someone with a condition may live after their diagnosis compared to someone without the condition of the same race, sex, and age over a specific time. This is different from the overall survival rate, which is the percentage of people still alive for a specific time after diagnosis of a condition.
It is most important to remember that figures are estimates, and everyone is different.
Learn more about the treatment options for colorectal cancer.
Gastrointestinal carcinoid tumors (GCTs) start in neuroendocrine cells, which are abundant throughout the gastrointestinal (GI) tract. These cells can be found in various parts of the body.
GCT
A GCT in the colon may cause a partial intestinal blockage. Symptoms may come and go for years and may include:
A GCT in the rectum may cause the following symptoms:
- pain
- rectal bleeding
- constipation
The carcinoid symptoms include:
- facial flushing
- diarrhea
- fast heart rate
Learn about the symptoms of rectal cancer.
Treatment and outlook
The standard treatment for GCT of the colon is a colectomy, which is surgery to remove all or part of the colon.
The main treatment for GCT of the rectum is surgery to remove the rectum. In some cases, surgeons may also remove the anus and part of the colon.
The 5-year relative survival rate for people living with GCT is
Learn all about a colectomy.
Lymphoma is cancer of the lymphatic system, which is the network of organs, tissues, and vessels that helps to balance body fluids and protect against infections.
Primary colorectal lymphoma (PCL) is a rare lymphoma that affects the colon or rectum. A 2019 study notes that PCL accounts for 0.4% of all CRCs.
Symptoms of PCL may include:
- abdominal pain and discomfort
- bloody stools
- changes in bowel habits
Learn more about lymphoma.
Treatment and outlook
According to a
However, one individual in this case study received combined surgery and chemotherapy, while the other received chemotherapy alone.
While both treatments were successful, large-scale studies with longer follow-ups are necessary to determine the longer-term outlook for individuals treated for PCL.
Learn more about chemotherapy for lymphoma.
Gastrointestinal stromal tumors (GISTs) originate in the nerve cells in the wall of the GI tract.
These tumors
Some GISTs develop slowly over time without causing problems, while others may grow and spread rapidly.
Depending on the location of the GIST within the GI tract, symptoms may include:
- blood in the stool or vomit
- abdominal pain
- painful or difficult swallowing
- feeling full after eating very little
- tiredness
Learn more about GIST.
Treatment and outlook
The treatment options for GISTs depend on whether doctors can remove the tumor surgically and whether the cancer has spread to other parts of the body.
Standard treatment options include:
- surgery
- targeted therapy
- watchful waiting
- supportive care
According to the
| Stage | 5-year relative survival rate |
|---|---|
| Localized | 95% |
| Regional | 84% |
| Distant | 52% |
Learn more about surgery for GISTs.
A leiomyosarcoma (LMS) is a rare cancerous tumor soriginating in smooth muscles.
According to a 2022 case report and literature review, sarcomas that originate in the colon and rectum account for less than
The most significant risk factor for LMS is a rare genetic condition called Li–Fraumeni syndrome (LFS).
In the case study, the individual experienced the following symptoms:
- painful and frequent bowel movements
- frequent urges to pass stools, combined with constipation
- rectal bleeding
- weight loss
Learn more about sarcomas.
Treatment and outlook
Surgical removal is the main treatment for LMS. According to the review, this approach cures LMS in
Unlike most other forms of colon cancer, LMSs tend to be resistant to other forms of cancer therapy, such as chemotherapy and radiotherapy.
Learn more about colon cancer.
Melanoma is a type of skin cancer that can spread to other parts of the body. A gastrointestinal melanoma (GIM) is a melanoma that occurs in the GI tract.
According to a
Very rarely, GIMs may be “primary,” meaning they originated in the part of the GI tract, such as:
- the rectum
- the anal canal
- the esophagus
GIM symptoms may include:
- abdominal pain
- constipation
- rectal bleeding
Learn about the differences between anal and rectal cancer.
Treatment and outlook
Treatment options for GIM include surgery and targeted therapies, such as BRAF inhibitors and immunotherapy.
Since the introduction of targeted therapies, survival times for this type of cancer have been increasing.
The review notes that the targeted therapy drug Nivolumab appears particularly effective for this type of cancer. Around 73% of people who took the drug for non-operable or metastatic GIM were alive 1 year after diagnosis.
Learn about the BRAF mutation in melanomas.
Squamous cell carcinoma (SCC) is a type of skin cancer that can spread to other parts of the body. Less commonly, it can originate in epithelial cells in other parts of the body, such as the GI tract. Doctors refer to this as Primary GI SCC.
Primary SCCs of the colon are particularly rare, accounting for less than
People with colorectal SCC may experience lower left-sided abdominal pain and weight loss.
Learn more about squamous cell carcinomas.
Treatment and outlook
Due to the rarity of colorectal SCC, medical professionals have yet to determine the most effective treatment approach and are unable to offer an accurate outlook.
Authors of a
Learn about treating SCC of the skin quickly to prevent it from spreading.
Familial adenomatous polyposis (FAP) is a rare inherited syndrome that predisposes a person to certain cancers.
People with this syndrome have hundreds to thousands of pre-cancerous adenomatous polyps. These polyps usually develop by age 16 and turn cancerous by the third or fourth decade of life.
Besides colorectal polyps, individuals with FAP may experience other complications, such as:
- polyps of the stomach, duodenum, and small bowel
- soft tissue tumors
- bony growths
Learn more about adenomatous polyps.
Treatment and outlook
The standard treatment for FAP is colectomy. Doctors may then prescribe the nonsteroidal anti-inflammatory drug (NSAID) Sulindac to treat polyps in the remaining rectum.
In most cases, polyps will return after surgical removal, so a person will require continued observation.
Learn more about polyp removal.
What is the most aggressive type of colon cancer?
According to a 2021 review, adenosquamous carcinoma (ASC) is a rare but particularly aggressive form of colorectal cancer and typically presents at the most advanced stage of the disease.
Compared to adenocarcinomas, ASC carries a poorer outlook across all disease stages.
Which type of colon cancer has the least favorable outlook?
According to the
What is the most common site for colon cancer?
According to a 2022 review, the most common site for colorectal cancer is the sigmoid colon, which is the final section of the colon. This section connects the colon and rectum. Around
How long can a person live with undiagnosed colon cancer?
The
Colorectal cancer is cancer that develops in the colon or rectum.
The most common type of colorectal cancer is adenocarcinoma. Most adenocarcinoma subtypes are slow growing. However, certain subtypes, such as signet ring and mucinous adenocarcinomas, can grow and spread rapidly.
Adenocarcinomas are more common than other types of colorectal cancer. These rarer types of CRC may cause different symptoms and may require different treatments.
A person who receives a diagnosis of colorectal cancer can speak with their doctor about their individual treatment options and outlook.