Metastatic liver cancer is a condition where cancer cells from another part of the body have spread to the liver, forming secondary tumors. It is distinct from primary liver cancer, which originates within the liver cells themselves. These secondary tumors are made up of cells from the original cancer, so a tumor from colon cancer found in the liver is composed of colon cancer cells. This distinction is important because it dictates the approach to treatment.
The Origin of Liver Metastases
The process of metastasis begins when cancer cells break away from their primary tumor. These cells can then enter the bloodstream or lymphatic system, allowing them to travel to distant parts of the body. The liver’s role in filtering blood makes it a common destination for these traveling cancer cells. It receives a dual blood supply from the hepatic artery and the portal vein, which carries blood directly from the digestive system.
This direct circulatory connection is why cancers of the gastrointestinal tract, especially colorectal cancer, frequently spread to the liver. Up to 70 percent of individuals with colorectal cancer may eventually develop liver metastases. Other common primary cancers that spread to the liver include those originating in the:
- Lung
- Breast
- Pancreas
- Stomach
Once these cells arrive in the liver, they can invade the surrounding tissue and begin to form new tumors.
Symptoms and Diagnosis
In the early stages, liver metastases may not produce any noticeable symptoms. The liver is a large organ and can continue to function normally even when small tumors are present. When symptoms do appear, they are often non-specific and can include:
- Fatigue or a general feeling of weakness
- Loss of appetite
- Unexplained weight loss
As tumors grow larger, they may cause pain in the upper right abdomen, bloating, or a feeling of fullness.
If tumors obstruct the flow of bile, a substance produced by the liver to aid digestion, it can lead to jaundice, a yellowing of the skin and the whites of the eyes. This blockage can also cause dark-colored urine and itchy skin. In some cases, fluid can accumulate in the abdomen, a condition known as ascites, causing swelling. Sometimes, the first sign of cancer is the discovery of these metastases during an examination for other health concerns.
Diagnosing liver metastases involves several tests. Doctors often start with blood tests called liver function tests, which can show elevated levels of certain enzymes if the liver is not working properly. Imaging tests are then used, including computed tomography (CT) scans, magnetic resonance imaging (MRI), and ultrasound, which reveal the location, size, and number of tumors. To confirm the diagnosis and determine the origin of the cancer cells, a liver biopsy is often performed, where a small sample of tissue is removed from a tumor and examined.
Treatment Approaches
The treatment plan for metastatic liver cancer is highly individualized and guided by the location of the original, primary cancer. For instance, metastatic colon cancer in the liver is treated with therapies effective against colon cancer. A combination of approaches is often used, falling into two main categories: therapies that treat the whole body and those that target the liver directly.
Systemic therapies circulate throughout the bloodstream to reach cancer cells wherever they may be. Chemotherapy uses drugs to destroy rapidly dividing cells. Targeted therapy is an approach that uses drugs designed to attack specific molecules on cancer cells, often with different side effects than chemotherapy. Immunotherapy works by stimulating the body’s own immune system to recognize and fight the cancer cells. These treatments aim to control the cancer’s growth and relieve symptoms.
Liver-directed therapies focus specifically on the tumors within the liver. Surgery to remove the tumors, known as a liver resection, may be an option if there are only a few metastases confined to a specific area. Ablation techniques use extreme temperatures, either heat or cold, delivered through a needle to destroy tumor tissue. Transarterial chemoembolization (TACE) injects chemotherapy drugs directly into the liver’s artery along with a substance that blocks blood flow. Stereotactic body radiation therapy (SBRT) is a form of radiation that delivers high, precise doses to tumors while sparing healthy tissue.
Prognosis and Managing Liver Function
The outlook for an individual with liver metastases can vary widely. It is influenced by several factors, including the type and stage of the primary cancer, the number and size of the tumors in the liver, and if the cancer has spread to other organs. A patient’s overall health and response to treatment also play a role. Management extends beyond treating the cancer to include supportive care aimed at preserving liver function and quality of life.
Managing symptoms is a part of the care plan. Pain, fatigue, and nausea can often be controlled with medication and other supportive measures. If the liver’s function is impaired, it can lead to complications like ascites, which may require procedures to drain the fluid. Another potential issue is hepatic encephalopathy, a condition where toxins build up in the blood, leading to confusion and drowsiness.
An interprofessional team, including oncologists, surgeons, radiologists, and nurses, collaborates to create a comprehensive treatment plan. This team approach ensures that all aspects of the patient’s condition are addressed. Regular monitoring of liver function through blood tests and imaging helps the healthcare team make adjustments to the treatment plan as needed.