Colon Cancer Stage IV

Stage 4 colon cancer occurs when cancer that starts in the colon spreads to other parts of the body. While this advanced stage presents significant challenges, modern treatments including surgery, chemotherapy, targeted therapies, and immunotherapy are helping more people live longer with better quality of life.

Table of contents

• What is stage 4 colon cancer?
• Categories of stage 4 disease
• Symptoms
• Diagnosis and testing
• Treatment options
• Outlook and survival

What is stage 4 colon cancer?

Stage 4 colon cancer, also known as metastatic colon cancer, is cancer that starts in the colon and spreads to other parts of the body^[1]. This is the most advanced stage of colon cancer. The cancer has traveled through the body’s lymphatic system (the network of vessels that carries fluid and immune cells) or bloodstream to reach distant organs^[2].

Up to half of the people diagnosed with colon cancer eventually develop cancer in other parts of the body. These spreading cancers are known as metastases^[1]. The most common places where colon cancer spreads include the liver, lungs, the abdominal cavity (the space inside the belly that contains organs), or distant lymph nodes^[1][2].

Approximately 20 to 30% of all colon cancer cases are diagnosed at stage 4 when first discovered^[3]. Interestingly, the likelihood of being diagnosed at stage 4 decreases with advanced age^[3].

Categories of stage 4 disease

Stage 4 colon cancer is divided into three distinct categories based on where and how extensively the cancer has spread^[2][8]:

Stage IVA means the cancer has spread to one area or organ that is not near the colon, such as the liver, lung, ovary, or a distant lymph node. The cancer has not spread to the tissue lining the wall of the abdomen, called the peritoneum^[2][8].

Stage IVB means the cancer has spread to more than one area or organ that is not near the colon, such as the liver, lung, ovary, or distant lymph nodes. Like stage IVA, it has not spread to the peritoneum^[2][8].

Stage IVC means the cancer has spread to the tissue that lines the wall of the abdomen (the peritoneum) and may have also spread to other distant areas or organs^[2][8].

Symptoms

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

General symptoms may include^[1]:

• Feeling full soon after eating
• A lump in the belly button area
• A change in bowel habits, such as more frequent diarrhea, constipation, or changes in stool shape
• Rectal bleeding or blood in the stool
• Iron deficiency anemia (a condition where the body lacks enough healthy red blood cells to carry oxygen), which can cause tiredness, weakness, and a change in skin color
• Ongoing discomfort in the belly area, such as cramps, gas, bloating, or pain
• A feeling that the bowel doesn’t empty all the way during a bowel movement
• Pain in the back, buttocks, or legs

Additional symptoms may appear depending on where the cancer has spread. If the cancer has spread to the liver, symptoms can include pain in the upper right part of the belly^[1].

Diagnosis and testing

Diagnosing stage 4 colon cancer involves multiple tests to detect cancer, determine its location, and understand its characteristics^[10].

Biopsy: 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 flexible tube with a camera is inserted through the rectum to view the colon). Sometimes surgery is needed to obtain the tissue sample. Laboratory tests can show whether the cells are cancerous, what type of cancer it is, and identify gene changes that may guide treatment strategies^[10].

Imaging tests: These tests create pictures of the inside of the body to look for areas of cancer. CT scans and MRI scans are the main imaging tests used to detect colon cancer and assess how far it has spread. A PET scan may also be helpful to decide if surgery is an option for cancer that has spread outside the colon^[10].

Molecular and genetic testing: 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. These tests help doctors choose the best treatment, as some medicines only work for certain gene changes^[10].

Carcinoembryonic antigen (CEA) testing: CEA is a protein made by some colon cancer cells. It can be measured with a simple blood test. High levels of CEA can indicate the presence or progression of colon cancer, especially in advanced or metastatic stages^[10].

Treatment options

Stage 4 colon cancer typically requires complex treatment strategies to manage symptoms and improve quality of life. Treatment may include chemotherapy, surgery, targeted therapy, immunotherapy, or radiation^[1]. The treatment plan depends on where in the body the cancer has spread, which biomarkers (specific features of the cancer cells that can be targeted by certain drugs) the cancer possesses, and what therapies have already been tried^[18].

Surgery

Surgery is indicated if the primary tumor and associated metastases are amenable to removal with the goal of cure, or if complications such as obstruction, bleeding, or perforation arise from the tumor^[3]. Surgery sometimes can be used if the cancer has spread to the liver or lungs. It may cure patients who have limited spread to those organs, or it may ease symptoms^[18].

The surgeon will remove the part of the colon, liver, or lungs where the cancer is located, along with nearby lymph nodes^[18]. After removing the cancerous part of the colon, the surgeon may sew the ends of the intestines together. Some people may need a colostomy, which attaches the end of the colon to an opening in the belly where waste leaves the body into a pouch worn outside^[18].

Chemotherapy

Chemotherapy uses drugs to kill cancer cells. Medical treatment with chemotherapy remains the mainstay of treatment when curative resection is not possible^[3]. You may receive chemotherapy through a tube in a vein or as a pill. Chemotherapy may be given before surgery to shrink tumors, after surgery to destroy remaining cancer cells, or alone if surgery isn’t possible^[18].

There are several kinds of chemotherapy drugs used to treat stage 4 colon cancer, and you may receive more than one. Doctors sometimes combine chemotherapy with targeted therapy^[18]. Patients who receive chemotherapy have increased median survival to 30 months compared to 9 months for those who do not pursue further treatment^[14].

Radiation therapy

Radiation uses high-energy X-rays to kill cancer cells^[18]. It may be used in select settings for palliative purposes.

Targeted therapy

Targeted therapies focus on specific molecules or pathways that help colon cancer grow. Unlike traditional chemotherapy, which attacks all fast-dividing cells, targeted therapies are more precise^[19]. For example, drugs like Bevacizumab and Ramucirumab work by preventing new blood vessel formation, which is crucial for tumor growth. Other drugs like Cetuximab target special protein receptors to halt tumor cell division and growth^[19].

Immunotherapy

Immunotherapy leverages the body’s own defense system to fight cancer. Recently, immunotherapy has shown promise at managing, controlling, and even causing regression of advanced disease. In some cases, it can convert the cancer to a state where curative resection becomes possible^[3]. Immune checkpoint inhibitors are one of the most effective types of immunotherapy for certain types of colon cancer^[19].

Biomarker testing

All stage 4 colon cancer patients should undergo biomarker testing. Biomarkers are targetable features of a cancer, often mutations or changes in specific genes that can be targeted by specific drugs. Testing helps the treatment team understand which therapies might work and which should be avoided^[25].

Outlook and survival

The 5-year survival rate for people with stage 4 colon cancer is about 13% to 15%^[7][14]. However, everyone is different, and many factors contribute to a person’s outlook. Some people live much longer than statistics suggest.

Thanks to screening tests, early treatment, and new kinds of treatment, fewer people are dying from colon cancer^[9]. Colorectal cancer, including metastatic colorectal cancer, continues to have improved 1-year and 5-year survival rates^[3]. Recent advances in surgery, chemotherapy, and immunotherapy have led to significant improvements in outcomes for late-stage colon cancer patients^[16].

For most people with stage 4 colon cancer, treatment is focused on prolonging overall survival and maintaining an acceptable quality of life rather than achieving a cure, unless the spread is limited and can be surgically removed^[14][18].