Esophageal cancer begins in the esophagus, the muscular tube connecting the throat to the stomach. Cancer cells can detach from the primary tumor and travel to other parts of the body, forming new tumors; this process is called metastasis. Understanding where and how esophageal cancer spreads is important for managing the disease.
Understanding Metastasis
Cancer cells can enter the body’s circulatory or lymphatic systems, which act as pathways to other regions. Once in these systems, cancer cells travel and settle in new tissues, where they begin to grow. Even when esophageal cancer spreads to another organ, the new tumor is still classified as esophageal cancer because it originated from esophageal cells.
Regional Lymph Nodes
Regional lymph nodes are often the first sites where esophageal cancer spreads. Lymph nodes are small, bean-shaped glands that are part of the immune system, filtering lymph fluid and housing immune cells. The esophagus has a rich network of lymphatic vessels, allowing cancer cells to easily enter these nodes.
The specific lymph nodes affected depend on the tumor’s location within the esophagus. For instance, upper esophageal tumors may spread to lymph nodes in the neck and upper mediastinum. Cancers in the middle and lower esophagus commonly involve lymph nodes in the mediastinum (chest cavity) and around the stomach. “Skip metastasis,” where cancer cells bypass closer lymph nodes to spread to more distant ones, can also occur.
Distant Organs
Beyond regional lymph nodes, esophageal cancer can spread to various distant organs, primarily through the bloodstream. The liver and lungs are the most common distant sites for esophageal cancer metastasis. This is partly due to their rich blood supply and their connection to the vascular system that drains the esophagus.
The liver is a frequent site of spread, with approximately 23% of metastatic esophageal cancers found there, likely because of its extensive blood flow and filtering function. The lungs are also a common destination, accounting for about 31% of cases. Tumors in the upper esophagus are more likely to spread to the lungs, while lower esophageal tumors often metastasize to the liver.
Bone metastasis can also occur, though it is less common than spread to the liver or lungs. Esophageal cancer can also spread to the brain, adrenal glands, and the peritoneum, which is the lining of the abdominal cavity.
Detecting Metastasis
Doctors use various methods to detect if esophageal cancer has spread. Imaging tests are frequently employed to visualize internal organs and identify suspicious areas. Common imaging techniques include Computed Tomography (CT) scans, which use X-rays to create detailed cross-sectional images of the body.
Positron Emission Tomography (PET) scans are also used, often in combination with CT (PET/CT), to detect metabolically active cancer cells throughout the body. Magnetic Resonance Imaging (MRI) can also be used, providing detailed soft tissue contrast. If imaging tests suggest metastasis, a biopsy may be performed on the suspected metastatic site to confirm the presence of cancer cells and determine their type.