Lung Cancer |
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Lung cancer represents the single most preventable lethal cancer in the United States. Every year, 175,000 people will be diagnosed with lung cancer and 160,000 people will die of lung cancer. In the past several decades, lung cancer has surpassed breast cancer as the leading cause of cancer-related deaths in women. The single biggest cause of lung cancer is smoking. It is estimated that at least 80% of lung cancer can be attributed to the effects of smoking, including exposure to second-hand smoke. Most lung cancers initially cause no symptoms and often spread early. As a result, only 40% of patients are diagnosed while the cancer is still in an early stage. And while surgery is the standard of care for early stage lung cancer, many patients will not be candidates for surgery either because the disease is too advanced at the time of diagnosis or the patient lacks the necessary lung function to tolerate or recover from surgery. For this reason, chemotherapy and radiation therapy are often employed in the treatment of both early and late stage lung cancer.
After a diagnosis of lung cancer is made, several studies will need to be done to determine how far the cancer has spread. These often include either a CT scan of the chest and abdomen or a PET/CT scan. PET/CT scanning has been found to improve staging in 25-50% of patients. PET/CT scan doesn’t usually image the brain particularly well and so CT or MRI of the brain is also done. For patients who present with new onset bone pain, a bone scan is often obtained, although the PET/CT scan may make this unnecessary. Early stage lung cancer (stage I/II) is confined to the initial site of growth (primary site), with or without local lymph node involvement. Locally advanced lung cancer (stage III) is either unresectable or has lymph node involvement at a more advanced level. Metastatic lung cancer (stage IV) represents patients whose disease has spread outside of the initial site of growth and lymph nodes. When such spread occurs, the disease often spreads to other parts of the lung or the brain, the bones, the liver, and the adrenal glands. Many other sites are possible, although much less common. Physicians evaluate multiple factors prior to deciding on a course of treatment for any given patient. The primary determinants of treatment are cell type (small cell versus non-small cell), extent of disease (stage I/II versus III or IV), and the patients overall physical condition. Early stage small cell lung cancer is generally treated with a combination of chemotherapy and radiation therapy. Advanced stage small cell lung cancer is generally treated with chemotherapy alone. Radiation therapy is used if the disease has metastasized to critical organs such as the brain or bones. Early stage non-small cell lung cancer is generally treated with surgery. Prior to surgery however, pulmonary function tests (PFT’s) are done to assess the patients overall breathing capacity. Based on the results of this study, some patients may not be a candidate for surgery. In this case, many patients are treated with radiation therapy. This can be done in a relatively short course (less than 10 treatments) or in a longer course, depending upon the extent and location of the disease and the condition of the patient. Most patients with locally advanced disease are treated with a combination of chemotherapy and radiation therapy. In this case, the radiation therapy is delivered over a course of 6-7 weeks, daily Monday through Friday.
Although generally safe, radiation therapy may cause either temporary or permanent changes in the body. The primary side effects of radiation therapy for lung cancer are fatigue, skin reaction, and difficulty with swallowing. Other symptoms include, but are not limited to, a dry cough, shortness of breath, potential damage to normal lung or heart, and a drop in the blood count. Damage to the spinal cord is possible but is quite rare. Recovering from radiation therapy can take from several weeks to many months. Some patients will experience difficulty with breathing that may not start until 2-4 months after treatment has been completed. On the other hand, the skin reaction and irritation of the esophagus usually heal quite quickly. The effectiveness of radiation therapy varies with the size of the lesion and the dose of radiation therapy that is delivered. In general, smaller tumors or tumors treated to a higher dose are easier to control than larger tumors or tumors treated to a smaller dose. |
Prior to making a decision about what treatment is most appropriate for any given patient, a biopsy and staging work up is done. Biopsies can be done at the time of bronchoscopy for more central lesions or by CT-guidance for more peripheral lesions. The pathology for lung cancer is divided into two main groups—small cell and non-small cell carcinoma. The treatment for each type is different as small cell lung cancer is typically treated with a combination of chemotherapy and radiation therapy (without surgery) and non-small cell lung cancer is typically treated with surgery for early, resectable disease and with a combination of chemotherapy and radiation therapy for more advanced disease.
Prior to starting radiation therapy, several procedures will need to be done to insure that the radiation therapy is delivered in an appropriate manner. The first step will be a simulation. During the simulation, the patient is aligned in the treatment position, tattoos are done to facilitate daily positioning, and a CT scan will be done with the patient in the treatment position. Once this is done, computer based treatment planning is done to aid in the delivery of a high dose of radiation to the tumor while keeping the dose to normal structures as low as possible. PET/CT fusion is extremely helpful in this and has been shown to improve target delineation in at least 20-30% of patients. Once this process is complete, the patient will be placed on the treatment table and films will be obtained to verify the positioning of the patient.