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Cancer of the Lower Lung
Lung cancer affects more than 200,000 new patients in the USA, and more than 150,000 may die of the disease every year. Although tobacco smoking has been associated as the most common risk factor in lung cancer patients, occupational exposure to asbestos is now recognized as the second most import cause.
It has been observed that about two thirds of lung cancer cases occur in the upper lobes of the lungs while the rest are found in the lower lobes. While many people with cancer in the upper lobes have a strong background of tobacco smoking, a study done by the Department of Thoracic and Cardiovascular Surgery of the Helsinki University Hospital from August 1988 to January 1992 showed that among the patients they examined with lower lobe lung cancer, a history of exposure to asbestos and laboratory findings of asbestos fibers in their lung tissues were common.
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What is Inoperable Lung Cancer?
Surgical removal of part of a lung, a lobe of a lung or the whole lung may be done to remove cancer-affected portions of the respiratory organ. This is traditionally done by performing a thoracotomy, which involves open surgery of the chest cavity. Surgery is usually indicated for early stages of lung cancer, when the malignancy has not affected the lymph nodes or other organs outside the chest cavity.
People with poor general health, advanced age and in the later stages of lung cancer may be considered poor candidates for surgery. Late stages of cancer may involve more tissues and organs like the bronchi, lymph nodes, the liver and the brain. Patients with concomitant lung disease like emphysema, poor pulmonary function, heart disease and other conditions are susceptible to post-operative adverse events. Survival rates are low while risks for complications are high.
Patients with inoperable tumors are asked to consider other forms of therapy with fewer risks.
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Treatments for Inoperable Lower Lung Cancer
Conventional radiation therapy using external beams of high-energy X-rays to kill cancer cells and to reduce tumor size involves application of 33 treatments spread over six weeks. Brachytherapy or internal radiation using radioisotopes may also be done by placing these in the area of the tumor. These radiotherapy techniques can decrease cancer recurrence but in late stages long term survival rates may not be improved. Radiation injuries to the esophagus, heart, normal lung and other tissues are common.
CyberKnife for treatment of lung cancer should be considered as a good alternative to either surgery or conventional radiation therapy. It delivers radiation with the precision of a computer controlled robotic technique, thus avoiding the risks of external beam radiation.
Radiofrequency (RF) ablation is a technique where high temperatures are used to kill the tumor cells by inserting a needle through the skin, and the technician, who is visually guided by CT scan targets the area involved. This is ideal when the isolated tumor such as that in the lower lung is located away from vital organs like the heart and the bronchi.
Cryotherapy uses liquid nitrogen to kill tumor cells by freezing them. The liquid nitrogen is delivered by steel probes inserted into the chest.
Chemotherapy in the form of oral and/or intravenous drugs may be given in cycles in an outpatient setting. Platinum-based drugs have been found to be the most effective in treatment of lung cancers. However, these drugs may also affect normal cells and produce undesirable side effects like nausea and vomiting, hair loss and fatigue.
Drugs like erlotinib (Tarceva) and gefitinib (Iressa) are used in targeted therapy which more specifically target cancer cells, resulting in less damage to normal cells and therefore fewer side effects.
Photodynamic therapy uses a photosynthesizing agent such as a porphyrin which penetrates and destroys tumor cells when activated by light applied by a surgeon. It is a precise technique but is not effective in treating extensive cancers.
Immunotherapy using vaccines that attempt to increase the body’s defense reaction against cancer cells are still in the experimental stages.
When surgery is not recommended, the choice to use one or a combination of these modalities of treatment for lower lung cancer may be taken. In doing so, one must consider the advantages and risks involved, as well as the expected results.
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Ignacio Castellon, MD et al, “Medically Inoperable Lung Cancer” http://cancernews.com/data/Article/480.asp
S Anttila et al, "Lung cancer in the lower lobe is associated with pulmonary asbestos fiber count and fiber size” http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1519739/pdf/envhper00372-0076.pdf
MedicineNet, “Lung Cancer”, http://www.medicinenet.com/lung_cancer/page6.htm#tocg