All About Lung Cancer
What is lung cancer?
Cancer that forms in tissues of the lung, usually in the cells lining air passages. Lung cancer is predominantly a disease of the elderly; almost 70% of people diagnosed with lung cancer are over 65 years of age, while less than 3% of lung cancers occur in people under 45 years of age.
Primary Versus Secondary Lung Cancer
Primary lung cancer begins in the lungs while the secondary lung cancer can metastasize or travel from another part of their body to the lungs.
Estimated new cases and deaths in 2013:
Lung cancer is the most common cause of death due to cancer in both men and women throughout the world. More patients die from lung cancer than breast, colon, prostate, and kidney cancer combined.
The American Cancer Society estimates that 228,000 new cases of lung cancer in the U.S. will be diagnosed and 160,340 deaths due to lung cancer would occur in 2013.
Cells are the building blocks that make up all tissues and organs of the body, including the lungs. Lung cancer, similar to any other cancer begins with an error, or mutation, in a cell’s DNA. DNA mutations can be caused by the normal aging process or through environmental factors, such as cigarette smoke, breathing in asbestos fibers, and to exposure to radon gas.
How lung cancer originates
Researchers have found that it takes a series of mutations to create a lung cancer cell. Before becoming fully cancerous, cells can be precancerous, in that they have some mutations but still function normally as lung cells. Due to the uncontrolled division or proliferation of abnormal cells in one or both of lungs a genetic mutation is able to sustain and spread or metastasize through various other parts of the body. The abnormality of these cells disrupts the functions of normal lung cells and malignant tumors form that are able to invade and spread throughout various organs of the body such as, the adrenal glands, liver, brain, and the bones. Due to the rapid rate at which these tumors spread, lung cancer is one of the most difficult cancers to treat.
It’s important to report any unusual physical feelings to your doctor as the signs and symptoms of lung cancer can take years to develop and they may not appear until the disease is advanced.
Lung Cancer Diagnosis
Screening procedure such as X-ray, CT scan of the chest may be ordered to initially test for lung cancer. An X- ray image may reveal an abnormal mass or nodule, while CT scan can detect small lesions that might not be detected on an X-ray. Looking at your sputum (mucus you cough up from the lungs) under the microscope can some time reveal the presence of cancer cells.
A biopsy can be performed to further investigate this diagnosis. In a biopsy, a small piece of tissue from the lung must be examined under a microscope to look for cancer cells. In some cases, the doctor passes a needle through the skin into the lungs to remove a small piece of tissue; this procedure is often called a needle biopsy. In other cases, a biopsy may be done during a bronchoscopy. To perform a bronchoscopy, the doctor inserts a small tube through the mouth or nose and into the lungs. The tube, which has a light on the end, allows the doctor to see inside the lungs and to remove a small tissue sample.
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Types and Staging of Lung Cancer
The two main types are non-small cell lung cancer (NSCLC) and small cell lung cancer (SCLC). These types are diagnosed based on how the cells look under a microscope.
Staging in lung cancer is based on whether the cancer is local or has spread from the lungs to the lymph nodes or other organs. Early-stage lung cancer (stages I and II) is difficult to detect because symptoms such as coughing or fatigue can often be overlooked. Most people with lung cancer are diagnosed at stages III and IV.
STAGES OF NON-SMALL CELL LUNG CANCER
Small Cell Lung Cancer
This type of lung cancer accounts for the remaining 15 percent of lung cancers in the United States. Small cell lung cancer results from smoking even more so than non-small cell lung cancer, and grows more rapidly and spreads to other parts of the body earlier than non-small cell lung cancer.
Stages of Small Cell Lung Cancer:
The American Joint Commission on Cancer has recently began using Roman numerals and letters to describe the stages of small cell lung cancer such as those used for non-small cell lung cancer.
Non-Small Cell Lung Cancer Treatment
Surgery, radiation, chemotherapy, and targeted treatments are all treatments which can be used separately or in combination to treat lung cancer. Although these treatments may cause different side effects, the side effects are listed separately along with helpful resources to manage the side effects.
Surgery is a procedure used to treat most Stage I and Stage II non-small cell lung cancers. In this procedure, the surgeon removes the tumor infested lobe using video-assisted thoracoscopic surgery (VATS). For this procedure, the surgeon makes a small incision, or cut, in the chest and inserts a tube called a thoracoscope. The thoracoscope has a light and a tiny camera connected to a video monitor so that the surgeon can see inside the chest. A lung lobe can then be removed through the scope, without making a large incision in the chest.
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Chemotherapy and Radiation
After a non-small cell lung tumor is surgically removed, chemotherapy, known as “adjuvant chemotherapy,” can help prevent the cancer from returning. This is particularly true for patients with stage II and IIIA disease however; the benefits related to other patients in regards of this procedure remain a topic for research.
For people with stage III lung cancer that cannot be removed surgically, doctors typically recommend chemotherapy in combination with definitive (high-dose) radiation treatments. In stage IV lung cancer, chemotherapy is typically the main treatment. In stage IV patients, radiation is used only for palliation of symptoms.
The chemotherapy treatment plan for lung cancer often consists of a combination of drugs. Among the drugs most commonly used are cisplatin (Platinol) or carboplatin (Paraplatin) plus docetaxel (Taxotere), gemcitabine (Gemzar), paclitaxel (Taxol and others), vinorelbine (Navelbine and others), or pemetrexed (Alimta).
In cases where treatment is ineffective or where the lung cancer resurfaces, doctors often prescribe a second course of drug treatment referred to as second-line chemotherapy.
Recently, the concept of maintenance chemotherapy has been tested in clinical trials, either as a switch to another drug before the cancer progresses; or to continue one of the drugs used initially for a longer period of time. Both of these strategies have shown advantages in selected patients.
Chemotherapy Before Other Treatments (Neoadjuvant Treatment)
Receiving chemotherapy before radiation or surgery may help patients by shrinking the tumor and making it easier to remove with surgery, as well as increasing the effectiveness of radiation and destroying hidden cancer cells at the earliest possible time. Research shows that people with lung cancer are much more able to cope with the side effects of chemotherapy when it is given before surgery.
Targeted therapies are designed specifically to attack cancer cells by attaching to or blocking targets that appear on the surfaces of those cells. People who have advanced lung cancer with certain molecular biomarkers may receive treatment with a targeted drug alone or in combination with chemotherapy.
Small Cell Lung Cancer Treatment
Chemotherapy and Radiation Therapy
Regardless of stage, chemotherapy is an essential part of treatment for patients with small lung cancer and radiation treatment may also be used depending on the stage of cancer. For people with limited-stage small cell lung cancer, combination chemotherapy plus radiation therapy given at the same time is the recommended treatment. The most commonly used initial chemotherapy regimen is etoposide (Toposar or Vepesid) plus cisplatin (Platinol), known as EP.For people with extensive-stage small cell lung cancer, chemotherapy alone using the EP regimen is the standard treatment. However, another regimen that may be used is carboplatin (Paraplatin) plus irinotecan (Camptosar).
Preventive Radiation Therapy to the Brain
In more than half of the people with small cell lung cancer, the cancer may also spreads to the brain. This procedure is known as prophylactic cranial irradiation (PCI) is a measure taken to help prevent cancer from spreading to the brain in patients whose lung cancer has responded to chemotherapy. This can benefit patient with both limited-stage and extensive-stage small cell lung cancers.
A very small percentage of people who have limited-stage small cell lung cancer and no lymph node tumors may benefit from surgery, after which adjuvant chemotherapy is given.
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Clinical trials are research studies that help to determine whether new treatments are safe and effective, or better than existing treatments. In most cases, the treatment that is being studied in a clinical trial has already shown promise of being an improvement over the standard treatment. Clinical trials are important because their results help doctors understand which treatments, or combinations of treatments, provide the best results. In lung cancer, clinical trials have helped doctors discover targeted treatments, as well as helping to define how best to combine chemotherapy and radiation.
If a new treatment offered in a clinical trial proves to be effective, it may become a new standard of care. Many of today’s most effective treatments are based on results from previous clinical trials. Because of progress made through clinical trials, many people with cancer are living longer and better. Patients enrolled in a clinical trial may be the first to receive new treatments before they become widely offered.
Some Causes of Lung Cancer
Smoking: The incidence of lung cancer is strongly correlated with cigarette smoking, with about 90% of lung cancers arising as a result of tobacco use. The risk of lung cancer increases with the number of cigarettes smoked and the time over which smoking has occurred; doctors refer to this risk in terms of pack-years of smoking history (the number of packs of cigarettes smoked per day multiplied by the number of years smoked). Pipe and cigar smoking also can cause lung cancer, although the risk is not as high as with cigarette smoking. Thus, while someone who smokes one pack of cigarettes per day has a risk for the development of lung cancer that is 25 times higher than a nonsmoker, pipe and cigar smokers have a risk of lung cancer that is about five times that of a nonsmoker.Tobacco smoke contains over 4,000 chemical compounds, many of which have been shown to be cancer-causing or carcinogenic. The two primary carcinogens in tobacco smoke are chemicals known as nitrosamines and polycyclic aromatic hydrocarbons. The risk of developing lung cancer decreases each year following smoking cessation as normal cells grow and replace damaged cells in the lung. In former smokers, the risk of developing lung cancer begins to approach that of a nonsmoker about 15 years after cessation of smoking.
Passive smoking: Passive smoking or the inhalation of tobacco smoke by nonsmokers who share living or working quarters with smokers, also is an established risk factor for the development of lung cancer. Research has shown that nonsmokers who reside with a smoker have a 24% increase in risk for developing lung cancer when compared with nonsmokers who do not reside with a smoker. An estimated 3,000 lung cancer deaths that occur each year in the U.S. are attributable to passive smoking.
Asbestos fibers: Asbestos is a natural mineral that is fireproof and insulating and was used in building construction materials and in some manufacturing processes. Once exposed to asbestos, the silicate fibers can remain in the lung tissue for a lifetime. When asbestos is inhaled, the fibers can irritate the lung and may eventually cause lung disease. Professional protective breathing equipment can reduce the risk of breathing in asbestos fibers for those who work with or around asbestos. Today, asbestos use is limited or banned in many countries, including the U.S.
Radon gas: Radon gas is a natural, chemically inert gas that is a natural decay product of uranium. Radon gas is a known cause of lung cancer, with an estimated 12% of lung-cancer deaths attributable to radon gas, or about 20,000 lung-cancer-related deaths annually in the U.S., making radon the second leading cause of lung cancer in the U.S. Radon gas can travel up through soil and enter homes through gaps in the foundation, pipes, drains, or other openings. You can purchase Environmental Protection Agency-approved kits in hardware stores to measure the amount of radon in your home.
Other factors include: Air pollution, Radiation exposure, Industrial substances, Tuberculosis, and Genetics
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Screening for Lung Cancer
Most lung cancers are first diagnosed based on symptoms since an early-stage lung cancer screening tool has only recently been made available.
Recent guidelines from the American Society of Clinical Oncologists suggests, annual screening with low-dose computed tomography (LDCT) for smokers and former smokers at high risk for developing lung cancer. High risk factors include being between the age of 55 to 74, having smoked for 30 years or more, and either continuing to smoke or having quit within the past 15 years. At this time, yearly screening with LDCT is recommended for high-risk individuals after careful discussion with their physicians.
CT (computerized tomography, computerized axial tomography, or CAT) scans may be performed on the chest, abdomen, and/or brain to examine for both metastatic and lung tumors. A CT scan of the chest may be ordered when X-rays do not show an abnormality or do not yield sufficient information about the extent or location of a tumor. CT scans are X-ray procedures that combine multiple images with the aid of a computer to generate cross-sectional views of the body. One advantage of CT scans is that they are more sensitive than standard chest X-rays in the detection of lung nodules, that is, they will demonstrate more nodules.
Sometimes intravenous contrast material is given prior to the scan to help delineate the organs and their positions. A CT scan exposes the patient to a minimal amount of radiation. CT scans of the abdomen may identify metastatic cancer in the liver or adrenal glands, and CT scans of the head may be ordered to reveal the presence and extent of metastatic cancer in the brain.