Colon Cancer Metastatic

Metastatic colon cancer, also known as stage 4 colon cancer, occurs when cancer that starts in the colon spreads to other parts of the body. While this advanced form of cancer presents serious challenges, new treatments and approaches are giving patients more options to manage symptoms, slow disease progression, and improve quality of life.

Table of contents

• What is metastatic colon cancer?
• How and where the cancer spreads
• Recognizing symptoms
• How doctors diagnose metastatic colon cancer
• Treatment approaches
• Understanding survival and prognosis
• Coping with metastatic colon cancer

What is metastatic colon cancer?

Metastatic colon cancer is cancer that starts in the colon and spreads to other parts of the body. This is also known as stage 4 colon cancer, late-stage cancer, or advanced cancer^[1]. The term metastasis refers to the process by which cancer cells break away from the original tumor and travel through the blood or lymph system to other parts of the body^[3].

Up to half of the people diagnosed with colon cancer eventually develop cancer in other parts of the body^[1]. Approximately 23% of people with colorectal cancer are diagnosed after their cancer has already metastasized^[20]. Metastatic colorectal cancer remains a serious disease with a 5-year survival rate of approximately 14%^[2].

Recent research has revealed something important about how this cancer spreads. Many colorectal cancers likely spread from the site where they first formed to other parts of the body long before the original tumor can be detected by current screening tests. Scientists now believe that colorectal cancer can spread very soon after the original tumor has developed, and maybe years before the disease is diagnosed^[3].

How and where the cancer spreads

Colorectal cancer cells can break away from the original tumor and travel through the blood or lymph system (a network of vessels that carry fluid and immune cells throughout the body) to other parts of the body^[3]. The most common locations where colon cancer spreads include the liver, lungs, abdominal cavity, and lymph nodes^[1][5].

The liver is the most frequent site of spread because blood from the colon flows directly to the liver before returning to the heart^[5]. Sometimes the cancer spreads to the lungs, bones, or other organs in the body^[5]. Cancer may also spread to the peritoneum, which is the tissue that lines the wall of the abdomen^[7].

In stage 4 colon cancer, doctors divide the disease into different categories based on how widely it has spread. Stage IVA means cancer has spread to one area or organ that is not near the colon, such as the liver, lung, or a distant lymph node. Stage IVB indicates cancer has spread to more than one area or organ. Stage IVC means cancer has spread to the tissue lining the abdominal wall and may have spread to distant areas or organs^[7].

Research shows that most metastatic colorectal cancers are started by a single cell, or a small group of similar cells, that break off from the original tumor early in its development. In about 80% of patients studied, the driver mutations (genetic changes that help cancer grow) found in the metastatic tumors were already present in the primary tumor, suggesting they arose early during tumor development^[3].

Recognizing symptoms

Colon cancer doesn’t always cause symptoms, even if it has progressed to stage 4. When symptoms do occur in metastatic colon cancer, they can be similar to colon cancer that hasn’t yet spread outside the colon^[1].

General symptoms may include feeling full soon after eating, a lump in the belly button area, changes in bowel habits such as more frequent diarrhea or constipation, or changes in stool shape. Other common signs are rectal bleeding or blood in the stool, which appears as bright red blood or dark, tar-like stools. People may also experience iron deficiency anemia (low red blood cell counts due to lack of iron), which can cause tiredness, weakness, and changes in skin color. Ongoing discomfort in the belly area, such as cramps, gas, bloating, or pain, is another possible symptom. Some people feel that the bowel doesn’t empty all the way during a bowel movement, or experience pain in the back, buttocks, or legs^[1][6].

When cancer has spread to other parts of the body, additional symptoms may appear depending on where the cancer has spread. If cancer spreads to the liver, symptoms can include discomfort or pain on the right side of the abdomen, feeling sick, poor appetite and weight loss, swollen abdomen (called ascites, a buildup of fluid in the belly), yellowing of the skin and eyes (called jaundice), and itchy skin^[1][6].

If cancer spreads to the lungs, people may experience a cough that doesn’t go away, breathlessness, coughing up blood, or a buildup of fluid between the chest wall and the lung. Cancer that has spread to the bones may cause an ache or pain in the affected bone. Sometimes damaged bones release calcium into the blood, causing symptoms like tiredness, feeling sick, constipation, irritability, thirst, and confusion^[6].

How doctors diagnose metastatic colon cancer

Metastatic colon cancer is diagnosed through a combination of imaging tests, lab tests, genetic testing, and tissue samples called biopsies^[9]. The diagnosis process usually involves several different procedures to understand the full extent of the disease.

A biopsy is a procedure to remove a sample of tissue for testing in a lab. For colon cancer, the tissue sample is often collected during a colonoscopy (a procedure where a tube is inserted into the anus to view the inside of the large bowel). Sometimes surgery is needed to get the tissue sample. In the lab, tests can show whether the cells are cancerous and what type of cancer it is^[9][5].

Imaging tests can look for areas of cancer inside the body. CT scans (computed tomography) and MRI scans (magnetic resonance imaging) are the main imaging tests used to detect colon cancer and assess how far the cancer has spread. A PET scan (positron emission tomography) may also be helpful to decide if surgery is an option for cancer that has spread outside the colon^[9]. Images from these tests help doctors see if colorectal cancer has spread into the chest or organs in the belly or pelvis^[5].

Other tests performed on the cancer cells can give information about the gene changes present in these cells and guide treatment strategies. Some colon cancers have gene changes that affect how the cancer grows and how well it responds to treatment. These genetic features are found by testing the cancer in a lab through molecular and genetic testing. These tests help doctors choose the best treatment, as some medicines only work for certain gene changes^[9].

A blood test called carcinoembryonic antigen (CEA) testing measures a protein made by some colon cancer cells. High levels of CEA can indicate the presence or progression of colon cancer, especially in advanced cases^[9][5].

If imaging tests show a mass in the liver or lung, a liver biopsy or lung biopsy might be done. A bone scan can help doctors find out if cancer cells have spread to the bones^[5].

Treatment approaches

Stage 4 colon cancer typically requires complex treatment strategies to manage symptoms and improve quality of life^[1]. Treatment for metastatic or recurrent colorectal cancer is based on many things, including the location of the cancer, your overall health, and what matters to you^[5].

The main treatments are surgery, chemotherapy (medicines that use chemicals to kill fast-growing cancer cells), or both. Treatment may also include targeted therapy (drugs that identify and attack specific types of cancer cells), immunotherapy (treatments that help your immune system attack and kill cancer cells), or radiation (high-energy rays to destroy cancer cells)^[1][5].

Surgery might be an option in some cases. You might have surgery to treat a blocked bowel, and sometimes doctors can remove small areas of cancer that have spread to the liver or lungs^[13][5]. For cancer that has spread to the liver, other treatment options may include thermal ablation (using heat to destroy tumors) and embolization (blocking blood flow to tumors)^[5]. Some specialized centers offer hepatic artery infusion, which delivers chemotherapy directly to tumors in the liver^[12].

Chemotherapy for metastatic bowel cancer can relieve symptoms, control the cancer, and improve quality of life for a time^[13]. The drugs circulate throughout the body in your bloodstream to destroy cancer cells^[13].

Radiotherapy uses high-energy rays to destroy cancer cells. You might have radiotherapy to shrink your cancer and help relieve symptoms^[13].

Targeted cancer drugs work by targeting the differences between cancer cells and normal cells that help them grow and survive. Other drugs called immunotherapies help the immune system attack cancer. Some drugs have very specific targets, and your team might need to do extra tests on the cancer to see if a particular drug might help. These drugs can shrink or slow the growth of metastatic bowel cancer^[13].

A clinical trial may be an option for you. Clinical trials are research studies that explore new treatments that are under investigation to confirm if they may work against metastatic colon cancer^[5][20]. Your doctor will talk with you about any trials that you can enter.

Treatment to control symptoms is an important part of care. Symptoms such as pain can often be managed. Treatment might include a tube (called a stent) to relieve symptoms from a bowel blockage, a tube to drain fluid from a swollen abdomen, or medicines to help control symptoms such as pain or feeling sick. Chemotherapy, surgery, radiotherapy, and targeted and immunotherapy drugs can all help control symptoms as well^[13].

Understanding survival and prognosis

Despite increasing survival rates, metastatic colorectal cancer remains a lethal disease with a 5-year survival rate of approximately 14%^[2]. However, this doesn’t mean that everyone will have the same outcome. Each person’s situation is different, and survival depends on many factors.

Treatment for metastatic bowel cancer can keep it under control, relieve symptoms, and give you a good quality of life. In a few people with metastatic bowel cancer, treatment can control the cancer for a long time. And for a small number of these people, a cure might be possible. This is usually only possible if cancer has spread to just one other body part and the surgeon can completely remove this cancer, as well as the cancer in the bowel^[18].

New treatments are changing the outlook for many people with metastatic colorectal cancer, even for some who have been told their condition is untreatable. Research continues to discover even better ways to help patients with metastatic colorectal cancer live longer and with less pain and fewer side effects from treatment^[12].

Coping with metastatic colon cancer

Finding out that you have metastatic cancer can be distressing and can be a shock. It’s common to feel uncertain and anxious. It’s normal to not be able to think about anything else^[18].

Many people find that knowing more about their situation can make it easier to cope. Talk to your doctor or specialist nurse to understand what your diagnosis means, what is likely to happen, what treatment is available, how treatment can help you, and what the side effects might be^[18].

Your friends and relatives might be able to support you and talk to you about your cancer. Sharing can help to increase trust and support between you and make it easier to plan ahead. You can help your family and friends by letting them know you would like to discuss what’s happening and how you feel^[18].

You might find it easier to talk to someone outside your own friends and family. Counselling (talking with a trained professional about your feelings and concerns) might help you find ways of coping with your feelings and emotions^[18].

Thinking about your priorities and planning what you want to do can help you to feel more in control. You might want to talk about how you want to spend your time and what is and isn’t important to you. You can talk to your doctor about managing your treatment around your plans^[18].

Community cancer nurses or symptom control nurses can help to support you at home. These professionals, often called palliative care teams, are in most cancer units, hospices, and many general hospitals. Most have home care services so they can visit you at home. They can give you medicines, help you get the equipment you need, suggest other ways of controlling your symptoms, or refer you to specialists who focus on symptom control^[6][18].