Colorectal cancer has a staging system that doctors use to indicate the size and spread of cancer, including parts of the body where the disease has spread.
Healthcare professionals can make decisions about treatment according to the TNM staging system. TNM describes the anatomical spread of cancer in terms of the tumor, nodes, and metastasis of the cancer.
According to 2020 data, colorectal cancer is the second leading cause of death globally, and cases are rising. It is the fourth most commonly diagnosed tumor in the world.
Tobacco and alcohol use, a sedentary lifestyle, consumption of red meat, and obesity are possible causes of cancer. Early detection systems and improved treatment options have reduced death rates, even with rising cases.
Colorectal cancer stages run
The cancer staging system already divides the stages using letters. If the letter is earlier in the alphabet, the stage is lower. However, the stage is only an indication. Each person will have a unique experience of cancer.
The cancer stage indicates the type of treatment a healthcare professional may suggest.
The staging depends on how far the cancer has spread in the layers of tissue in the colon or rectum, which include the:
- Mucosa: the inner lining where colorectal cancer often starts
- Muscularis mucosa: the thin muscle layer included in the mucosa
- Submucosa: the fibrous tissue beneath the muscle layer
- Muscularis propria: the thick muscle layer
- Subserosa/serosa: the thin outer layers of connective tissue found in the colon but not the rectum
The American Joint Committee on Cancer (AJCC) decides the staging system for cancer. The system (TNM) classifies:
- T: how far the tumor has grown into the layers of rectum or colon wall
- N: whether the tumor has spread to lymph nodes near the site of the tumor
- M: whether the tumor has metastasized, or spread, to other sites in the body, including the liver or lungs
The first edition of the AJCC staging system appeared in 1977. The AJCC periodically updates the document when new information about treatment and diagnosis becomes available. New information may change the staging.
A wide representation of cancer and treatment specialists from the global healthcare community contributed to the AJCC eighth edition.
The AJCC eighth edition uses pathological or surgical means for diagnosing how a tumor has spread. Examining tissue removed during surgery enables healthcare specialists to find the correct stage for a tumor.
Colorectal cancer may have no symptoms at all. When it does cause symptoms, they may
- bowel habit changes, including:
- the need to have a bowel movement, which is not relieved by going to the toilet
- blood in the stool, which makes the poop appear dark brown or black
- bright red blood coming from the anus
- abdominal pain or cramps
- fatigue and weakness
- unintentional weight loss
- lack of red blood cells or anemia
According to the
- a physical examination, which looks for an enlarged organ or a mass in the abdomen
- medical history
- a stool test to look for blood
- blood tests to examine liver function, look for tumor markers, or check the amounts of different types of cells
- diagnostic colonoscopy, which uses a small video camera to examine the length of the colon and rectum
- proctoscopy, which uses a small video camera to check the rectum
- biopsy, which involves removing a small piece of tissue for analysis
- genetic testing, which enables a healthcare specialist to find specific gene changes in the event cancer spreads
- imaging tests, including:
|0||Tis||N0||M0||Indicates early stage cancer that has not grown beyond the inner layer of the colon or rectum.|
|1||T1 or T2||N0||M0||Indicates that cancer is in the inner layer and possibly the thin muscle layer. It has not spread to the lymph nodes or to more distant sites.|
|2A||T3||N0||M0||The cancer has spread into the outer layers of the colon or rectum and is confined there. It has not spread to distant sites or lymph nodes.|
|2B||T4a||N0||M0||The cancer has grown through the rectum or colon wall. It has not spread into other tissues nor into lymph nodes or other organs.|
|2C||T4b||N0||M0||The cancer has grown through the rectum or colon wall or has grown into other nearby organs or tissues. It has not spread to nearby lymph nodes or distant organs.|
|3A||T1 or T2||N1 or N1c||M0||The cancer has grown into the inner layers of the colon or rectum wall. It may have grown into the thick muscle layer. The tumor has spread to 1–3 lymph nodes or into areas of fat near the lymph nodes, excluding the nodes themselves (N1c). It has not spread to other organs.|
|3A||T1||N2a||M0||The cancer has spread through the two inner layers of the colon or rectum wall. It has spread to 4–6 nearby lymph nodes. It has not spread to other organs.|
|3B||T3 or T4a||N1 or N1c||M0||The cancer has spread into the thick muscle or outermost layers of the rectum or colon wall or through and into the abdominal cavity lining (T4a). The tumor has spread to 1–3 lymph nodes or fat areas near lymph nodes, but not the actual nodes. Distant organs are not affected.|
|3B||T2 or T3||N2a||M0||The cancer has spread through the inner layers. It may have spread into the thick muscle layer. The tumor has spread to 7+ nearby lymph nodes. It has not spread to distant organs.|
|3B||T1 or T2||N2b||M0||The cancer has grown through the inner layers and may have spread to the thick muscle layer. The tumor has grown in 7+ nearby lymph nodes but has not spread to distant organs.|
|3C||T4a||N2a||M0||The cancer has spread through the colon or rectum wall, including the abdominal cavity lining. It has not spread to nearby organs (T4a). The tumor has affected 4–6 nearby lymph nodes but has not spread to distant organs.|
|3C||T3 or T4a||N2b||M0||The cancer has grown into the outer layers of the colon or rectum wall or through the abdominal cavity lining. It has not reached the organs nearby. It has spread to 7+ nearby lymph nodes but not to distant organs.|
|3C||T4b||N1 or N2||M0||The cancer has grown through the wall layers of the colon or rectum. It is spreading to tissues or organs within reach. The tumor has grown in at least one nearby lymph node or fat near the nodes. It has not spread to distant organs.|
|4A||Any T||Any N||M1a||The cancer may or may not have grown through the colon or rectum wall. The tumor may have spread to nearby lymph nodes. It has spread to one distant organ, including the liver or lungs, or distant nodes. The tumor has not spread to distant parts of the peritoneum.|
|4B||Any T||Any N||M1b||The cancer may or may not have spread through the rectum or colon wall. The tumor may or may not have grown into nearby lymph nodes. It has spread to a number of distant organs or distant nodes. It has not grown in the distant parts of the abdominal cavity lining.|
|4C||Any T||Any N||M1c||The cancer may or may not have spread through the wall of the colon or rectum. The tumor may or may not have spread to nearby lymph nodes or distant nodes. Cancer has grown in distant parts of the abdominal cavity lining and may or may not have spread to distant organs, such as the liver or lungs.|
Treatment of colorectal cancer depends on the stage of cancer and where it has spread. Treatment may involve more than one type. It may also depend on a person’s overall health and test results.
- surgery to remove the affected part of the colon or rectum
- chemotherapy to kill tumor cells
- radiation therapy
- targeted therapy
Researchers measure cancer survival rates by the number of people living for 5 years or more following diagnosis.
New technologies have improved treatment. In addition, screening tests have enabled earlier detection, giving people a better chance of recovering.
However, people’s socioeconomic status and race may affect how likely they are to survive. For example, in the United States, African Americans and Native Americans are less likely to have access to quality healthcare. Because of this, they have
- Localized: The cancer has not spread beyond the colon or rectum.
- Regional: The cancer has spread to nearby structures or lymph nodes.
- Distant: The cancer has spread to distant organs or distant lymph nodes.
The 5-year relative survival rates for colon cancer between 2011 and 2017 are:
- Localized: 91%
- Regional: 72%
- Distant: 14%
- Average of all stages: 64%
The 5-year relative survival rates for rectal cancer between 2011 and 2017 are:
- Localized: 90%
- Regional: 73%
- Distant: 17%
- Average of all stages: 67%
Finding the right support is an important part of
- National Cancer Information Center (NCIC): The
NCICprovides support and information through phone, video chat, and live chat for people living with cancer, their caregivers, and family members. The NCIC connects people with local community services as well.
- Cancer Survivors Network (CSN): The CSN provides an online community for people affected by cancer to share support and information through chat rooms, discussion boards, and private messages.
Doctors use the AJCC TNM staging system to find how far cancer has spread.
There are four stages and several levels to each stage depending on which part of the body is affected by cancer.
The AJCC regularly updates the system according to new research and diagnostic methods.
Survival rates for colorectal cancer are improving, thanks to earlier detection and treatment.