Types There are several types of small cell lung cancer, defined by the tumor's appearance under the microscope. These include small cell, mixed small cell/large cell and combined small cell (small cell with non-small cell tumor elements). It is unclear whether these types of tumor have different prognoses.
This tumor arises from what are called neuroendocrine cells and is known as an APUD (amine precursor uptake decarboxylation) tumor. Under the electron microscope, hormone-producing (neurosecretory) granules can be seen. These tumors, therefore, can abnormally produce hormones and cause what are called paraneoplastic syndromes. For example, if the tumor produces too much cortisone , the condition is called Cushing's syndrome . If antidiuretic hormone (ADH) is produced, water is retained in the body and the salt (sodium) level measured in the bloodstream decreases. Each of these paraneoplastic syndromes produces its own signs and symptoms.
How It Spreads Small cell lung cancer can spread via lymphatic vessels to the lymph nodes in the center of the lung (hilar nodes), the center of the chest (mediastinal nodes), in the neck and above the collarbone (supraclavicular nodes), and in the abdominal cavity. It is likely to spread through the bloodstream to the liver, lungs, brain and bone.
