Are swollen lymph nodes an indication of cancer?
Dear OncoLink "Ask The Experts,"
Can you get a pretty good indication of whether a child might have lymphoma or a neuroblastoma from blood work? If a child has symptoms (swollen nodes-several and large, increasing in size). Would the blood work always show irregular if they had a Cancer that involves the Lymph nodes or could they still have a cancer with normal blood work?
I really appreciate your attention to this matter.
Amit Maity, MD, PhD, Assistant Professor of Radiation Oncology at the Hospital of the University of Pennsylvania, responds:
First, of all, swollen nodes in a child may not represent cancer. There are many other conditions, including a wide variety of infections, that can cause enlarged nodes. Therefore, one should should not jump to the conclusion that this has to be cancer.
To answer your question, blood work alone may not distinguish lymphoma from neuroblastoma. First of all, it is possible to have either disease with completely normal blood work of the type that is normally ordered. A CBC (complete blood count) is likely to be normal in either disease unless the bone marrow has been infiltrated. Serum electrolytes such as sodium, potassium, chloride, etc. are unlikely to be abnormal in either disease. There is a serum chemistry marker called LDH (lactate dehydrogenase) that can be elevated in either disease. This is thought to correlate with tumor burden. However, if it is normal, this does not rule out lymphoma or neuroblastoma. A high LDH level is not even specific for cancer since many other medical conditions can elevate this marker. There is another serum chemistry marker called ferritin that is often elevated in neuroblastoma, but not typically in lymphoma. This particular marker is not one that would be routinely ordered by a physician. If the serum ferritin is extremely high in a young child with neck nodes, this would be more suggestive of neuroblastoma than lymphoma. However, a normal serum ferritin does not rule out neuroblastoma. Conversely there are other medical conditions that could cause an elevation in ferritin.
There is another test would suggest neuroblastoma over lymphoma, but this is not a blood test . Rather it is a measurement of urinary catecholamines. These are chemicals that are secreted in large amounts by neuroblastoma cells and spill over into the urine. However, again there are caveats since other conditions may increase these.
Because of all these subtleties and complexities, the interpretation of these test results is best left up to someone who has expertise in this area. The only way to be absolutely be certain about a diagnosis is to perform a biopsy of the nodes. If these nodes persist and there is a high index of suspicion that they are not simply reactive lymph nodes from a benign infection such as a sore throat, then this is what eventually needs to be done.