Answers to Your Most Pressing Questions About Lung Cancer and Lymph Nodes

Along with a lung cancer diagnosis come details that can make the news all the more overwhelming. One of these pertains to lymph node involvement. If you’ve just been told you have lung cancer, you may wonder why your lymph nodes are a concern.  With this in mind, Everyday Health asked Mara Antonoff, MD, to explain why it’s important to know how a person’s lymph nodes play a role in lung cancer.

EH: What are lymph nodes and how do they come up in the context of cancer and lung cancer?

MA: Lymph nodes are glands that act as filters for harmful substances such as infectious bacteria and other potentially dangerous pathogens. Altogether, the lymphatic system is part of the immune system. Some cancers spread through the arteries and veins, while others are inclined to go through the lymphatic vessels. Lung cancer can do both, but it generally travels through the lymph vessels first.

EH: What are the signs of a cancerous lymph node?

MA: There’s rarely any external signal or symptom that lymph nodes are involved. It’s not like lumps in the armpit, which can indicate breast cancer. In lung cancer, lymph nodes are hard to notice. The usual signs of lung cancer are coughing, a cough that produces blood, and/or wheezing. It’s uncommon, but sometimes when a patient has an advanced stage of lung cancer, they might see knots or nodules above the collarbone.

EH: What stage is lung cancer when it’s in the lymph nodes?

MA: Once lung cancer spreads beyond the lungs, it’s no longer considered stage I. From there it gets more complicated, however. Metastatic lung cancer can be either stage II, III, or IV, depending on the size of the tumor, which lymph nodes are involved, and if the cancer has reached other body parts as well. For lung cancer it’s more about which lymph nodes are involved, rather than the number of them. Basically, the closer the affected nodes are to the tumor, the lower the stage. The farther they’ve spread beyond it, the higher the stage.

EH: Does lung cancer in lymph nodes show up on a CT scan?

MA: A CT scan with IV contrast helps us notice when lymph nodes are enlarged. But lymph node size doesn’t necessarily mean the patient has cancer in the lymph nodes; it just raises the suspicion. The next test we might run would be a noninvasive test, like a PET scan. It’s possible the lymph node might light up brightly on a PET scan, which would be concerning and suspicious but not conclusive. If the area doesn't light up brightly on the PET scan, on the other hand, it would be reassuring but no guarantee it wasn’t cancer.

EH: What does the word “reactive” mean in the context of lymph nodes?

MA: You might hear that word in reference to PET scan findings. PET scans detect the rate at which cells are using sugar. When the scan lights up brightly, it means there is metabolic activity. Most aggressive cancers light up brightly, but the caveat is inflammation in the body also lights up because inflammatory cells are also metabolically active. That’s why we need to verify the scan results with a needle biopsy. I don’t usually use the term “reactive” by itself. Usually what I tell patients is: “The lymph node looks bright and that might be because it’s reactive to something in that area.”