Small Cell Lung Cancer – An Overview
Small cell lung cancer (also called oat cell carcinoma) accounts for 15% of lung cancers. Unlike the more common non-small cell lung cancers, small cell lung cancer grows rapidly, but often responds well to chemotherapy initially. Unfortunately, it tends to become more resistant to treatment as the disease progresses.
Small cell lung cancers usually begin in the large airways (bronchi) of the lungs, but spread early, often to the brain. They are broken down into only two stages, limited and extensive stage small cell lung cancer. 60 to 70% of people already have extensive stage disease at the time of diagnosis.
Most cases of small cell lung cancer are due to smoking, although other causes can contribute as well. This type of lung cancer is more common in men than in women, and is the most common type of lung cancer to have symptoms referred to as paraneoplastic syndrome -- that is, symptoms due to hormones secreted by a tumor or by the body’s immune response to a tumor.
SymptomsSymptoms of small cell lung cancer can include:
- Persistent cough
- Coughing up blood (hemoptysis)
- Swelling in the face and neck
- Shortness of breath
- Repeated episodes of pneumonia or bronchitis
- Unexplained weight loss
Symptoms due to spread of the tumor to other regions of the body, for example:
- Bone – Causing pain in the back, hips, or ribs
- Brain – Causing headaches, vision changes, weakness, or seizures. Small cell lung cancer has often spread to the brain at the time of diagnosis.
Lung Cancer Spread to the Brain – Symptoms, Treatments, and Prognosis
Small cell lung cancer can also result in a broad variety of symptoms due to paraneoplastic syndromes. Some of these include:
- Muscle weakness in the upper limbs, vision changes, and difficulty swallowing (Lambert-Eaton myasthenic sydrome)
- Weakness, fatigue, and a low sodium level in the blood (syndrome of inappropriate antidiuretic hormone secretion (SIADH))
- Loss of coordination and difficulty speaking (paraneoplastic cerebellar degeneration)
- Clubbing (rounding) of the fingernails
StagesThere are 2 stages of small cell lung cancer:
- Limited Stage Lung Cancer - Limited stage small cell lung cancer is defined as a small cell cancer that is present in only one lung and may have spread to nearby (supraclavicular) lymph nodes or to the space between the lungs (mediastinum), but has not spread (metastasized) to other regions of the body.
- Extensive Stage Lung Cancer - In extensive stage small cell lung cancer, the cancer has spread (metastasized) to another region of the body, such as another lobe of the lungs or the brain.
Many people respond well to a combination of chemotherapy and radiation therapy; with limited stage cancer, this can offer the potential for a cure. If individuals respond well to treatment, prophylactic cranial irradiation (PCI) -- preventative radiation therapy to the brain -- is recommended to lower the risk that any cancer cells that have spread to the brain, but aren’t seen on radiology studies, will grow and cause symptoms.
Common medications used include a combination of cisplatin (Platinol) or carboplatin (Paraplatin) with etoposide (VePesid). In limited stage disease, the addition of radiation therapy appears to improve survival, whereas with extensive stage disease, radiation may be used to control symptoms (palliative therapy) related to the spread of cancer, such as bone pain.
Surgery is rarely performed for small cell lung cancer (it is usually considered inoperable), but is occasionally considered if a tumor is present in only one lung and nearby lymph nodes. Adjuvant chemotherapy (chemotherapy after surgery) is usually recommended if surgery is done for small cell lung cancer.
Clinical trials are in progress for both stages of small cell lung cancer, evaluating new treatments and treatment combinations for this aggressive cancer. According to the National Cancer Institute, all individuals with small cell lung cancer may be considered for inclusion in clinical trials.
PrognosisThe overall survival rate for small cell lung cancer is, sadly, only about 6%.
For limited stage small cell lung cancer, survival rates have improved since the addition of radiation therapy to treatment, and the use of PCI. The median survival rate (the time at which 50% of people have died and 50% are still alive) is 16-24 months, with a 2-year survival rate of 40-50% -- though only 10% of people with limited stage disease show no evidence of cancer 2 years after diagnosis. The survival rate at 5 years is 14% with treatment.
For extensive stage small cell lung cancer the median survival with treatment is 6 to 12 months with treatment, and only 2 to 4 months without treatment.
Factors that are associated with improved survival include female gender, and better performance status -- that is better health in general at the time of diagnosis. Continued smoking may lower survival. Since small cell lung cancer grows rapidly, and since we have come a long way with other fast-growing cancers such as leukemia, it is hoped that better treatments will be found in the future.
CopingStudies suggest that learning what you can about your lung cancer can improve your quality of life, and possibly even your outcome. Ask questions. Learn about clinical trials that might be appropriate for you. Consider joining a support group. Ask for your loved ones' help you in your journey with cancer.
National Cancer Institute. Small Cell Lung Cancer Treatment (PDQ). Health Professional Version. 07/01/09. http://www.cancer.gov/cancertopics/pdq/treatment/small-cell-lung/HealthProfessional.
National Institute of Health. Medline Plus. Lung Cancer – Small Cell. 08/09/09. http://www.nlm.nih.gov/medlineplus/ency/article/000122.htm.
Samson, D. et al. Evidence for Management of Small Cell Lung Cancer. AACP Evidence-Based Clinical Practice Guidelines (2nd Edition). Chest. 2007. 132(3 Suppl):314S-323S.
Sher, T. et al. Small cell lung cancer. Mayo Clinic Proceedings. 2008. 83(3):355-67.