Small cell cancer is a type of lung cancer.
Most small cell cancers start in the lung but they can first occur elsewhere in the body—for example in the bowel, bladder or prostate. Small cell cancers grow fast and spread quickly, so they are hard to cure. Small cell lung cancer is sometimes called oat cell cancer because the abnormal cells look like oats under the microscope.
Blood and lymph moves through the lungs as it circulates throughout the body. So it is very easy for small cell cancer cells to spread very quickly. This kind of cancer can spread to any organ, but most commonly affects the brain, liver, adrenal glands, and bone.
In most cases, by the time it is discovered, it has already reached other parts of the body. Often small cell cancers are in other organs even before it shows up on imaging tests. That's why it can't be cured simply by removing the lung tumor. The standard treatment includes chemotherapy with or without radiation, but not surgery.
Small cell cancers can sometimes act like miniature glands. They can secrete a range of chemicals and hormones. These substances can make a person sick in and of themselves. Doctors call this paraneoplastic (par-uh-knee-oh-plas-tick) disorder or phenomenon.
Sometimes it is the symptoms of paraneoplastic disorder that make doctors suspect cancer. Examples include:
Abnormal mineral levels, such as low blood sodium or potassium
High blood sugars in someone who is not diabetic
Unusual types of muscle weakness
Atypical neurological symptoms
Small cell lung cancers often grow very close to the largest and most important blood vessels in the chest. It is not uncommon for a large vein called the superior vena cava to become blocked by a small cell tumor. This hinders blood flow from the head and brain back to the body. This problem is called superior vena cava syndrome and is a medical emergency. Symptoms include headache, a red face, a bloated look to the head, and bulging veins in the front of the chest and neck.