When cells of the lung start growing rapidly in an uncontrolled manner, the condition is called lung cancer. Cancer can affect any part of the lung and it's the leading cause of cancer deaths in both women and men in the United States, Canada, and China.
Two main types of lung cancer exist: small-cell lung cancer (SCLC, also called oat cell cancer) and non–small-cell lung cancer (NSCLC). Small-cell lung cancer accounts for approximately 10%-15% of all cases of lung cancer.
Small-cell lung cancer differs from non–small-cell lung cancer in the following ways:
- Small-cell lung cancer grows rapidly.
- Small-cell lung cancer spreads quickly.
- Small-cell lung cancer responds well to chemotherapy(using medications to kill cancer cells) and radiation therapy (using high-dose X-rays or other high-energy rays to kill cancer cells).
- Small-cell lung cancer is frequently associated with distinct paraneoplastic syndromes (a collection of symptoms that result from substances produced by the tumor).
Small-Cell Lung Cancer Causes
- The predominant cause of both small-cell lung cancer and non–small-cell lung cancer is tobacco smoking. However, small-cell lung cancer is more strongly linked to smokingthan non–small-cell lung cancer.
- Even secondhand tobacco smoke is a risk factor for lung cancer. Those living with a smoker have a 20% to 30% increase in the risk of developing lung cancer compared to people who are not exposed to second hand smoke.
- All types of lung cancer occur with increased frequency in people who mine uranium, but small-cell lung cancer is most common. The prevalence is increased further in persons who smoke.
- Exposure to radon (an inert gas that develops from the decay of uranium) has been reported to cause small-cell lung cancer.
- Exposure to asbestos greatly increases the risk of lung cancer. A combination of asbestos exposure and cigarette smoking increases the risk even further.
Symptoms of Small-Cell Lung Cancer
Persons with small-cell lung cancer typically have had symptoms for a relatively short time (eight to 12 weeks) before they visit their doctor.
The symptoms can result from local growth of the tumor, spread to nearby areas, distant spread, paraneoplastic syndromes, or a combination thereof.
- Symptoms due to local growth of the tumor include the following:
- Symptoms due to spread of the cancer to nearby areas include the following:
- Hoarse voice, resulting from compression of the nerve that supplies the vocal cords
- Shortness of breath, resulting from compression of the nerve that supplies the muscles of the diaphragm, or the lungs filling with fluid and Stridor (sound produced by turbulent flow of air through a narrowed part of the respiratory tract) resulting from compression of the trachea(windpipe) or larger bronchi (airways of the lung)
- Difficulty swallowing, resulting from compression of theesophagus(food pipe)
- Swelling of the face and hands, resulting from compression of the superior vena cava (vein that returns deoxygenated bloodfrom the upper body)
- Symptoms due to distant cancer spread depend on the site of spread and can include the following:
- Spread to the braincan cause headache, blurring of vision,nausea, vomiting, weakness of any limb, mental changes, andseizures.
- Spread to the vertebral column can cause back pain.
- Spread to the spinal cord can cause paralysis and loss of bowel orbladder
- Spread to the bone can cause bone pain.
- Spread to the livercan cause pain in the right upper part of theabdomen.
- Symptoms due to paraneoplastic syndromes include the following:
- Symptoms may or may not be characteristic of a specific organ system.
- Nonspecific symptoms include fatigue, loss of appetite, andweightgain or loss.
- Severe muscle weakness.
- Trouble with balance or walking.
- Changes in mental status.
- Changes in skin color, texture, and facial features.
When to Seek Medical Care
- Consult a doctor if any of the following symptoms are present:
- Call 911 if any of the following symptoms are present:
Exams and Tests for Lung Cancer
- Initial exams and tests for suspected lung cancer may include the following:
- Medical, surgical, work, and smokinghistory
- Physical examto check for general signs of health
- Chest X-ray
- CT scanof the chest: An X-ray machine linked to a computer takes a series of detailed pictures of the inside of the chest from different angles. Other names of this procedure are computed tomography, computerized tomography, or computerized axial tomography.
- Thoracentesis: The lungs are enclosed in a sac. Lung cancer can cause fluid to collect in this sac. This is called pleural effusion. In people who have cancer, this fluid may contain cancer cells. The fluid is removed by a needle and examined for the presence of cancer cells.
- Bronchoscopy: This is a procedure used to look inside the trachea (windpipe) and large airways in the lung for abnormal areas. A bronchoscope (a thin, flexible, lighted tube with a tiny camera on the end) is inserted through the mouthor nose and down the windpipe. From there, it can be inserted into the airways (bronchi) of the lungs. During bronchoscopy, the doctor looks for tumors and takes a biopsy sample (a sample of cells that is removed for examination under a microscope) from the airways.
- Lung biopsy: If a tumor is on the periphery of the lung, it may not be seen with bronchoscopy. Instead, a biopsy sample has to be taken with the help of a needle inserted through the chest wall and into the tumor. This procedure is called a transthoracic needle biopsy.
- Mediastinoscopy: This procedure is performed to determine the extent the tumor has spread into the mediastinum (the area of the chest between the lungs). Mediastinoscopy is a procedure in which a tube is inserted behind the breastbone through a small cut at the lowest part of the neck. Samples of the lymph nodes (small, bean-shaped structures found throughout the body) are taken from this area to look for cancer cells.
- Once the patient has been diagnosed with lung cancer, exams and tests are performed to find out whether the cancer has spread (metastasized) to other organs. These tests help determine the stage of the cancer. Staging is important, because lung cancer treatmentis based on the stage of the cancer. Tests used to detect the spread of cancer may include the following:
- Blood tests: Complete blood count-- CBC -- provides information about the type and count of different types of blood cells, serumelectrolytes, kidney function, and liver function. In some cases, these tests may identify the site of metastasis. These tests are also important to assess the organ functions before starting treatment.
- CT scan of the chest and abdomen: An X-ray machine linked to a computer takes a series of detailed pictures of areas inside the body from different angles. The doctor may inject a dye into a vein. A contrast agent may be given to swallow so that the organs or tissues more clearly show up on the scan.
- MRI: MRI is an imaging technique used to produce high-quality images of the inside of the body. A series of detailed pictures of areas inside the body are taken from different angles. The difference between an MRI and CT scan is that MRI uses magnetic waves, whereas CT scan uses X-rays for the procedure.
- Radionuclide bone scan: With the help of this procedure, the doctor determines whether the lung cancer has spread to the bones. The doctor injects a minute quantity of radioactive material into the vein; this material travels through the bloodstream. If the cancer has spread to the bones, the radioactive material collects in the bones and is detected by a scanner.
- PET scan: a small amount of radioactive material is injected into the bloodstream and measures the metabolismof the organs to see if the cancer has spread.
- Staging of the cancer provides important information about the outlook of the patient's condition and helps the doctor plan the best treatment. Although other cancers are categorized from stage I to stage IV, small-cell lung cancer is classified in two stages.
- Limited stage: In this stage, the tumor is confined to one side of the chest, the tissues between the lungs, and nearby lymph nodes only.
- Extensive stage: In this stage, cancer has spread from the lung to other parts of the body.
Small-Cell Lung Cancer Treatment
The most effective treatment for small-cell lung cancer is chemotherapy (using medications to kill cancer cells), either alone or in combination with radiation therapy (using high-dose X-rays or other high-energy rays to kill cancer cells).
Chemotherapy uses powerful drugs to kill cancer cells. These medications may be taken bymouth (orally), but they are usually injected into a vein (IV).
Chemotherapy is a systemic treatment because the drugs enter the bloodstream, travel throughout the body, and kill cancer cells wherever they are. However, some normal cells are also killed. This is responsible for some of the side effects of chemotherapy.
Chemotherapy is usually given at intervals to ensure that the bone marrow has recovered before the next dose of chemotherapy is given.
Extensive research and clinical trials have identified different chemotherapy medications for the treatment of small-cell lung cancer.
An oncologist (cancer specialist) recommends chemotherapy specific to the patient’s condition.
Some drugs are used alone, while some are used in combination with others for greater effectiveness. An oncologist (cancer specialist) recommends chemotherapy specific to the patient’s condition.
Treatment of limited-stage small-cell lung cancer
- Currently, cisplatin, etoposide, vincristine, doxorubicin, andcyclophosphamideare the most commonly used medications for the treatment of persons with small-cell lung cancer.
- Standard treatment of small-cell lung cancer involves combination chemotherapy with a cisplatin-containing regimen. Treatment cycles are repeated every three to four weeks. People receive treatment for four to six cycles.
- Some doctors start radiotherapy to the chest as early as possible, while others may give it with the fourth cycle of chemotherapy.
- Radiation and chemotherapy: Sequential-radiation treatment may be given, followed by chemotherapy.
- However, in comparative studies, the earlier the radiation is started concurrently with chemotherapy (as early as the first cycle of chemotherapy), the better the outcome.
- If the patient has limited disease, and has had a complete remission, of the cancer, radiation therapy may be given to the patient’sbrainto reduce the risk of small-cell lung cancer spreading to the brain. This is called prophylactic cranial irradiation (PCI). It is usually given after the patient has completed the full chemotherapy, and radiotherapy (to the thorax). The radiation doses are low, and the treatment duration is short, so the side effects of this therapy are minimal.
Treatment of extensive-stage small-cell lung cancer (small-cell lung cancer that remains incurable with current treatment options)
- Persons with extensive-stage small-cell lung cancer are treated with combination chemotherapy. Currently, the combination of cisplatin or carboplatinand etoposide (PE) is the most widely used regimen.
- Radiation therapy may be used for relief of the following symptoms:
- Bone pain
- Compression of the food pipe (esophagus), windpipe, spinal cord, or superior vena cava caused by tumors
- Obstructive pneumonia caused by the tumor
Treatment of relapse of small-cell lung cancer
- Persons who have a relapse of small-cell lung cancer have an extremely poor prognosis.
- If the disease does not respond to treatment or progresses after initial treatment (called "refractory disease") or if the disease relapses within six months of completion of therapy, the person has little chance of responding to additional chemotherapy. The most common drug used in this setting is topotecan.
- Persons whose cancer does not progress for more than six months may be given additional chemotherapy, including re-treatment with their original chemotherapy regimen.
- Persons with relapsed or refractory small-cell lung cancer may enroll in a clinical trial. For information about ongoing clinical trials, visit the National Cancer Institute's Clinical Trials.
Other drugs may be given to prevent and treat adverse effects of radiation, chemotherapy, or the cancer itself, such as nausea or vomiting. Pain medications are also important to relieve pain due to cancer or its treatment.
Surgery plays little, if any, role in the management of small-cell lung cancer because almost all cancers have spread by the time they are discovered.
The exceptions are the relatively small number of people (less than 15%) whose cancer is discovered at a very early stage of the disease, when the cancer is confined to the lung without any spread to the lymph nodes. However, surgery alone is not considered curative, so chemotherapy is also given. Sometimes radiation therapy will also be needed if the cancer had spread to the nearby lymph nodes.
Radiation therapy is the use of high-dose X-rays or other high-energy rays to kill cancer cells. Radiation can be given from outside the body using a machine (external radiation therapy), or it can be given with the help of radiation-producing materials that are implanted inside the body (brachytherapy).
Radiation therapy can be curative (kills all cancer cells), prophylactic (reduces the risk of cancer spreading to the area to which it is given), or palliative (helps reduce suffering).
- Patients who are receiving chemotherapy require close monitoring for side effects and response to therapy.
- A blood workup, including CBC (complete blood count), is needed prior to each cycle of chemotherapy to ensure that the bone marrow has recovered before the next dose of chemotherapy is given.
- Kidney function is monitored, especially if the patient is taking cisplatin, as it can damage thekidneys. Also, carboplatin's dosage is based upon kidney function.
- The patient will undergo a CT scan to assess their response to treatment
- Other tests are performed to monitor liver function and electrolytes -- especially sodium andmagnesium levels -- due to the effects of the cancer and its treatment.
Palliative and terminal care
Because small-cell lung cancer is diagnosed in most people when it is not curable, palliative care becomes important. The goal of palliative and terminal care is to manage pain and discomfort and enhance quality of life.
Palliative care not only focuses on comfort but also addresses the concerns of the patient’s family and loved ones. Caregivers may include family and friends in addition to doctors, nurses, and other health careprofessionals.
Lung Cancer Prevention
Unlike many other cancers, lung cancer is associated with known risk factors for the disease. The predominant cause of lung cancer is tobacco smoking; therefore, the most important means of preventing lung cancer is to quit smoking.
Products that are available to help quit smoking include nicotine gum, medicated nicotine sprays or inhalers, nicotine patches, and oral drugs. In addition, group therapy and behavioral training further increase the chances of quitting.
For information about how to quit smoking, visit the following links:
- National Cancer Institute, Clearing the Air, Quit Smoking Today
- American Lung Association, Freedom From Smoking
Other risk factors for lung cancer include asbestos, radon, and uranium exposure. Take precautions to reduce or eliminate exposure to such harmful substances.
Outlook for Small-Cell Lung Cancer
The success of treatment depends on the stage of small-cell lung cancer.
In most people with small-cell lung cancer, the disease has already spread to other organs of the body by the time it is diagnosed.
People with small-cell lung cancer in the advanced stage cannot be cured. They usually survive less than one year.
Treatment may be moderately successful for persons with limited-stage disease. In those whose lung cancer is limited to the lung, the five year survival rate is about 52 percent.
The overall 5-year survival rate for persons with small-cell lung cancer is less than 20%. Also, long-term survivors have an increased change of having cancer again.