Types and differences of small cell lung cancer

There are three types of small cell lung cancer (SCLC). These types are named for their appearance under a microscope and the kind of cell found in the cancer.

• Small cell carcinoma (oat cell)
• Mixed small cell/large cell carcinoma
• Combined small cell carcinoma (a mix of SCLC with squamous cell or glandular cells)

Signs and symptoms of small cell lung cancer

Like non-small cell lung cancer, SCLC typically does not show symptoms until it has spread. Not all symptoms are the same in every patient. Many of the symptoms are the same as in non-small cell lung cancer, including:

• Persistent cough
• Coughing up blood (hemoptysis)
• Chest pain, particularly during deep breathing
• Wheezing
• Shortness of breath
• Persistent hoarseness
• Pain or difficulty breathing or swallowing
• Repeated infections (e.g., bronchitis, pneumonia)
• Swelling of the face and neck
• Weight loss
• Loss of appetite
• Fatigue

SCLC is also associated with a number of endocrine syndromes because the cancer cells secrete neuroendocrine hormones. When these syndromes are caused by tumors, they are called paraneoplastic syndromes and are different from those caused by NSCLC.  In some cases, the signs and symptoms of a paraneoplastic syndrome eventually lead to a diagnosis of SCLC. Signs and symptoms of paraneoplastic syndromes include the following:

• Syndrome of inappropriate antidiuretic hormone (SIADH). A hormone that decreases urine output and dilutes blood salt levels. Symptoms of SIADH include fatigue, loss of appetite, muscle weakness or cramps, nausea, vomiting, confusion and restlessness. Untreated, SIADH can lead to seizures and coma.
  
  
• Excessive blood clot formation. Clots most often develop in the veins of the legs, impeding blood flow. However, they may also occur in blood vessels to other limbs, the lungs, brain or other vital areas of the body.
  
  
• Loss of balance and coordination.

Symptoms that may appear as the cancer metastasizes will reflect the area involved, and may include:  

• Pain at metastatic sites (e.g., bones)
• Confusion or seizures
• Headaches
• Double vision
• Chest pain
• Masses near the skin’s surface

To date, there is no screening test that has been proven to prevent people from dying of lung cancer. Scientists have studied the effectiveness of chest x-rays, certain CAT scans and cytology testing of sputum as screening tools. However, there is no conclusive evidence that these tests can find lung cancer early enough to make a difference in improving the chance of survival. For this reason, routine screening is not considered a standard practice among the general population.