Lung cancer originates in the cells of the lungs, forming a tumor. The lymphatic system, a network of vessels and small, bean-shaped organs called lymph nodes, is part of the body’s immune defense. It filters lymph fluid. When lung cancer spreads to these lymph nodes, it indicates the disease has progressed beyond its initial site.
The Lymphatic System and Cancer Spread
The lymphatic system is a network that transports immune cells. Lymph nodes, clustered throughout the body, filter lymph fluid, trapping foreign substances like bacteria, viruses, and cancer cells. White blood cells within the nodes, such as lymphocytes, identify and eliminate these invaders.
Cancer cells can break away from the primary lung tumor and travel through the lymphatic vessels to nearby lymph nodes. There, they can become trapped and grow, forming new tumors. This spread, known as lymph node metastasis, signals a more advanced stage of the disease.
The extent of cancer spread to lymph nodes indicates cancer progression. Lymph nodes closest to the lungs are often the first affected, as they filter cells from the original tumor. The involvement of specific lymph node groups and their proximity to the primary tumor are important factors in determining the cancer’s stage. While not automatically indicating distant metastasis, lymph node involvement suggests potential for further spread and may require more aggressive treatment.
Diagnosing Lymph Node Involvement
Detecting lung cancer in lymph nodes involves a combination of imaging techniques and invasive procedures. Computed tomography (CT) scans can reveal enlarged lymph nodes, which might suggest cancer. However, an enlarged lymph node on a CT scan is not a definitive diagnosis, as infections can also cause swelling.
Positron emission tomography (PET) scans, often combined with CT (PET/CT), offer a more detailed view by showing metabolic activity in tissues. Cancer cells have higher metabolic rates and thus “light up” on a PET scan, indicating cancer in lymph nodes. While PET/CT scans are helpful for identifying suspicious areas, they are not always conclusive, and further investigation is needed to confirm cancer presence.
To definitively diagnose cancer in lymph nodes, invasive procedures obtain tissue samples. Endobronchial ultrasound (EBUS) with transbronchial needle aspiration (TBNA) is a minimally invasive procedure. During EBUS-TBNA, a thin, flexible tube with an ultrasound probe and a needle is inserted through the mouth into the airways to visualize and biopsy lymph nodes near the lungs and trachea. This outpatient procedure is safe and allows for direct sampling of suspicious lymph nodes.
Another invasive procedure is mediastinoscopy, a standard for evaluating mediastinal lymph nodes. This surgical procedure involves a small incision above the breastbone, through which a scope is inserted to visualize and biopsy lymph nodes in the mediastinum, the area between the lungs. While highly accurate, mediastinoscopy is more invasive than EBUS-TBNA and requires general anesthesia. Surgical lymph node sampling, sometimes performed during lung cancer surgery, involves removing lymph nodes to test for cancer cells and helps determine the extent of the disease.
Treatment and Outlook
The presence and extent of lung cancer in lymph nodes significantly influence treatment decisions. The N-stage in lung cancer staging categorizes lymph node involvement, with higher N-stages indicating more widespread disease. This staging information helps guide oncologists in developing a personalized treatment plan.
Treatment approaches for lung cancer with lymph node involvement involve a combination of therapies. Surgery may be considered if the cancer spread to lymph nodes is limited and resectable. However, if the cancer has spread extensively to lymph nodes, especially in the mediastinum, surgery alone is not sufficient, and a multidisciplinary approach is preferred. In such cases, radiation therapy, which uses high-energy rays to destroy cancer cells, is employed to target affected lymph nodes and the primary tumor.
Chemotherapy, which involves anti-cancer drugs administered intravenously or orally, is a systemic treatment that can kill cancer cells throughout the body, including those in lymph nodes. It is given before surgery to shrink tumors (neoadjuvant chemotherapy) or after surgery to eliminate any remaining cancer cells (adjuvant chemotherapy). Targeted therapy, another systemic approach, uses drugs that specifically block the growth and spread of cancer cells by interfering with particular molecules involved in tumor growth. These therapies are chosen based on genetic mutations identified in the cancer cells.
Immunotherapy, a newer treatment modality, harnesses the body’s own immune system to fight cancer. These drugs, such as checkpoint inhibitors, help the immune system recognize and attack cancer cells more effectively. The prognosis for individuals with lung cancer in lymph nodes varies widely, depending on factors such as the specific type of lung cancer, the number and location of involved lymph nodes, and the patient’s overall health. While lymph node involvement indicates a more advanced stage, ongoing advancements in treatment options offer a range of possibilities, and outcomes can differ significantly among individuals.