Colorectal Cancer Stage IV

Stage 4 colorectal cancer represents the most advanced form of the disease, where cancer has spread beyond the colon or rectum to distant organs. Despite the serious nature of this diagnosis, advances in treatment now offer more options and improved survival rates compared to previous decades.

Table of contents

• What is Stage IV Colorectal Cancer?
• Subcategories of Stage IV Disease
• Symptoms
• Diagnosis
• Treatment Options
• Prognosis and Survival

What is Stage IV Colorectal Cancer?

Stage 4 colorectal cancer is cancer that starts in the colon or rectum and spreads to other parts of the body^[1]. This advanced stage is also known as metastatic, late-stage, or distant colorectal cancer^[1]. The term metastatic refers to cancer that has moved from its original location to other areas through the lymph system or bloodstream.

Up to half of people diagnosed with colon cancer eventually develop cancer in other parts of the body^[1]. The most common locations for colorectal cancer to spread include the liver, lungs, abdominal cavity, and distant lymph nodes^[1][2]. At initial diagnosis, approximately 20 to 30% of all colorectal cancer cases are already at stage IV^[3].

Subcategories of Stage IV Disease

Stage IV colorectal cancer is divided into three distinct subcategories based on how far the cancer has spread^[2][13].

Stage IVA means the cancer has spread to one area or organ that is not near the colon or rectum. This could be the liver, lung, ovary, or a distant lymph node^[2]. The cancer is found without spread to the peritoneum, which is the tissue lining the abdominal cavity^[3].

Stage IVB indicates the cancer has spread to more than one area or organ that is not near the colon or rectum^[2]. Like stage IVA, this spread does not include the peritoneum^[3].

Stage IVC means the cancer has spread to the peritoneal surface and may also have spread to other distant sites or organs^[2][3].

Symptoms

Colon cancer does not always cause symptoms, even when it has progressed to stage 4^[1]. When symptoms do occur, they can be similar to colorectal cancer that has not yet spread outside the colon or rectum.

General symptoms may include^[1]:

• Feeling full soon after eating
• A lump in the belly button area
• Changes 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, which can cause tiredness, weakness, and changes in skin color
• Ongoing discomfort in the belly area, such as cramps, gas, bloating, or pain
• A feeling that the bowel does not empty completely during a bowel movement
• Pain in the back, buttocks, or legs

Additional symptoms depend on where the cancer has spread. When cancer spreads to the liver, symptoms may include pain in the upper right part of the belly^[1]. When cancer spreads to the lungs, it may cause shortness of breath or coughing.

Diagnosis

Metastatic colon cancer is diagnosed through a combination of imaging tests, lab tests, genetic testing, and tissue samples called biopsies^[10].

A biopsy is a procedure to remove a sample of tissue for testing in a laboratory^[10]. 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 examine the colon. Sometimes surgery is needed to obtain the tissue sample.

Imaging tests 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 it has spread^[10]. 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.

Some colon cancers have gene changes that affect how the cancer grows and responds to treatment. These genetic features are found by testing the cancer in a laboratory, and these tests help doctors choose the best treatment^[10]. Some medicines only work for certain gene changes.

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

Treatment Options

Stage 4 colon cancer typically requires complex treatment strategies to manage symptoms and improve quality of life^[1]. Treatment may include chemotherapy, surgery, targeted therapy, immunotherapy, or radiation^[1].

For most people with stage 4 colorectal cancer, treatment is focused on controlling symptoms and prolonging life rather than curing the disease^[18]. The goal is to prolong overall survival and maintain an acceptable quality of life. Medical therapy with chemotherapy remains the mainstay of treatment in cases where complete removal of the cancer is not possible^[3].

Surgical intervention may be indicated if the primary tumor and associated metastases can be completely removed^[3]. Surgery may also be necessary if the tumor causes complications such as obstruction, bleeding, or perforation of the bowel. Complete removal of liver, lung, and peritoneal metastases, when possible, is associated with better disease control and survival^[3].

Chemotherapy involves using drugs to kill cancer cells or stop them from growing. Targeted therapy uses drugs that target specific features of cancer cells, such as particular gene mutations. Immunotherapy works by helping the body’s own immune system recognize and attack cancer cells^[3]. Recently, immunotherapy has shown promise in managing, controlling, and sometimes even reversing advanced disease, in some cases making it possible to remove the cancer with surgery.

Treatment decisions for stage 4 colorectal cancer require consultation with a team of specialists, including medical oncologists who manage drug treatments, surgical oncologists who perform operations, and radiation oncologists who oversee radiation therapy^[3]. A multidisciplinary evaluation is crucial to selecting the most appropriate treatment pathway.

Prognosis and Survival

The 5-year survival rate for people with stage 4 colon cancer is about 13%^[7]. However, this is a general statistic, and everyone’s situation is different. Other factors contribute to a person’s outlook beyond the stage of cancer.

The average 5-year relative survival rate for all stages of colorectal cancer combined is 65.1%^[14], but this drops significantly to 15.1% for stage 4 disease^[18]. Patients with metastatic disease who do not pursue treatment have a median survival of about 9 months, while those who receive chemotherapy have increased median survival to approximately 30 months^[18].

Thanks to advances in surgical techniques, systemic therapy, and a better understanding of tumor biology and the importance of molecular profiling, more patients can now anticipate prolonged survival^[14]. Colorectal cancer continues to have improved 1-year and 5-year survival rates, and this trend is likely to continue.