Stage 4 colon cancer occurs when cancer in the colon spreads, or metastasizes, to other tissues and organs. Colon cancer most often spreads to the liver, but it may also reach the lungs, the lymph nodes, or the lining of the abdominal cavity.
However, everyone is different, and other factors contribute to a person's survival rate.
The correct diagnosis of colon cancer may take patience, as doctors use many tests to detect and locate cancer.
If they identify cancer, they will also use more tests to see whether it has spread.
The tests and processes that can aid a colon cancer diagnosis include:
- a physical examination
- blood tests
- a colonoscopy to look inside the rectum
- a biopsy, in which the doctor takes a sample of tissue and sends it to a laboratory for analysis
- molecular testing to help identify specific characteristics of the tumor that may be important for treatment
- imaging tests, such as CT, PET, ultrasound, or MRI scans, to see whether cancer has spread
- a chest X-ray to check whether cancer has spread to the lungs
After running all of the necessary tests, a doctor will discuss the diagnosis with the individual.
Anyone who receives a stage 4 colon cancer diagnosis will have to make some decisions about the way forward, particularly regarding treatment options.
It is important to discuss all of the options with a doctor and to understand the goal of each treatment.
The treatment options available to people with stage 4 colon cancer are more limited than those suitable for the earlier stages of this cancer. However, there are still some treatment options to consider, as well as other factors to keep in mind.
When cancerous cells have spread to distant organs and tissues, surgery is unlikely to cure cancer. There are some cases in which surgery may still be a good option, though.
If a scan reveals that the cancer has only spread to a few small areas, surgery may still be possible. By surgically removing the cancerous cells, doctors hope to help the person live longer.
These surgeries will involve the removal of part of the colon as well as the nearby lymph nodes. Additional surgery may remove the areas of tissue into which the cancer has spread. Doctors will typically also recommend chemotherapy, either before or after the surgery.
If the tumor cells are too large to remove, or there are too many of them, doctors will recommend chemotherapy before the person undergoes any surgical procedures. If this shrinks the tumors, they may then ask a surgeon to proceed with the surgery.
Doctors may also need to perform additional surgical procedures if the cancerous growth is likely to obstruct the colon or is already blocking it. In some cases, minimally invasive surgery, such as placing a stent, may be possible. Surgeons can place a stent, which is a hollow tube that typically consists of mesh metal or plastic, into the colon during a colonoscopy. When successful, a stent may help keep the colon open and make more invasive surgery unnecessary.
Doctors may also recommend a diverting colostomy, which essentially cuts the colon above the cancerous tissue and diverts the waste from the body out through a small opening in the skin.
If the colon cancer has spread too far for surgery to be effective, chemotherapy is the primary treatment option.
Most people with stage 4 colon cancer will receive chemotherapy or specific targeted therapies to help control the cancer progression or symptoms.
Doctors may recommend some treatment regimens that include a targeting drug, which targets either the vascular endothelial growth factor (VEGF) pathway or the epithelial growth factor receptor (EGFR) pathway.
The choice between regimens will vary in each situation. The most suitable option will depend on the types of treatment that a person has had before, their overall health, and their responsiveness to treatment.
It is not uncommon for doctors to try multiple treatments. If the cancer does not respond to the first treatment, they may stop that treatment and start another instead.
Doctors may also recommend radiation therapy in late-stage colon cancer to help reduce symptoms such as pain and discomfort. This treatment might even shrink the tumor for a time, but it will not usually cure the cancer.
Hepatic artery infusion
A hepatic artery infusion may be a treatment option for people with colon cancer that has spread to the liver. Hepatic artery infusion is a type of regional chemotherapy, which involves delivering a chemotherapy drug directly into the hepatic artery in the liver. This treatment may help destroy cancer cells without harming the healthy liver cells in the process.
Ablation or embolization
Ablation or embolization may be appropriate for people who have metastatic or reoccurring colorectal cancer that causes a few tumors in the lung or liver that are less than 4 centimeters across.
Ablation uses either radio frequencies, microwaves, or alcohol — which people also call percutaneous ethanol injection (PEI) — to target and kill cancer cells while leaving the surrounding tissues relatively unharmed.
During embolization, a doctor will inject substances into the blood vessels to try to block or reduce the blood flow to cancer cells in the liver.
If cancer progresses to many distant organs and tissues, surgery may not help extend a person's lifespan. Other treatment options can cause discomfort and may produce additional symptoms that make the person's quality of life worse.
In these cases, people may decide against medical treatment that seeks to cure the cancer and instead opt for palliative care to try to make living more comfortable.
Palliative care will typically involve finding ways to manage pain and reduce a person's symptoms so that they can live comfortably for as long as possible.
As the ACS note, colon cancer is the third most commonly diagnosed cancer in both males and females in the United States. One in 22 men and one in 24 women will receive a colon cancer diagnosis during their lifetime.
Stage 4 colon cancer is late-stage cancer in which the disease has spread to other tissues or organs in the body and is, therefore, more difficult to treat. Treatment may only be partially successful, and cancer may be more likely to return after treatment.
The ACS note that the 5-year relative survival rate for stage 4 colon cancer is 14%. However, this does not account for other factors that may affect individual survival rates.
For instance, the success of particular treatment methods may vary among individuals, with treatments that work very well for some people having little effect in others.
Additionally, experts base these statistics on past cases. As treatments tend to get better over time, survival rates may also improve as more effective treatments become available.
Individual factors can also play a significant role in a person's outcome. For instance, the age and overall health of an individual may affect their responsiveness to treatment.
The rate of cancer progression may change the outlook as well. If the cancer causes complications, such as a blockage in the colon or a hole in the bowel wall, the person's outlook is likely to change.
This survival statistic also only applies to stage 4 colon cancer when doctors first diagnose it. The survival rate will be different for those in whom the cancer has spread further or returned after treatment.
Stage 4 colon cancer is late-stage cancer. Life expectancy is lower than it is for earlier stages of cancer. The 5-year relative survival rate for stage 4 colon cancer that has spread to other parts of the body is about 14%. However, other factors, such as the chosen treatment methods and the person's overall health, contribute to life expectancy.
Although there are often still several treatment options available, including surgery and chemotherapy, some people with late-stage cancer choose not to have medical treatment and to seek palliative care instead.
Anyone who receives a diagnosis of stage 4 colon cancer should work closely with their medical team to discuss all the treatment options and decide what will best suit their needs.