Lung Cancer – Mostly Caused by Smoking

Lung Cancer occurs when this uncontrolled cell growth begins in one or both lungs. Rather than developing into healthy, normal lung tissue, these abnormal cells continue dividing and form lumps or masses of tissue called tumors. Tumors interfere with the main function of the lung, which is to provide the bloodstream with oxygen to be carried to the entire body. If a tumor stays in one spot and demonstrates limited growth, it is generally considered to be benign. More dangerous, or malignant, tumors form when the cancer cells migrate to other parts of the body through the blood or lymph system. When a tumor successfully spreads to other parts of the body and grows, invading and destroying other healthy tissues, it is said to have metastasized. This process itself is called metastasis, and the result is a more serious condition that is very difficult to treat. Lung Cancer is called “primary” if the cancer originates in the lungs and “secondary” if it originates elsewhere in the body but has metastasized to the lungs. These two types are considered different cancers from diagnostic and treatment perspectives. Lung Cancer is usually found in older persons because it develops over a long period of time.

Classification of Lung Cancer

Lung cancer can be broadly classified into two main types based on the cancer’s appearance under a microscope: non-small cell lung cancer and small cell lung cancer. Non-small cell lung cancer (NSCLC) accounts for 80% of lung cancers, while small cell lung cancer accounts for the remaining 20%.

  • Squamous cell carcinoma or epidermoid carcinoma. As the most common type of NSCLC and the most common type of lung cancer in men, squamous cell carcinoma forms in the lining of the bronchial tubes.
  • Adenocarcinoma. As the most common type of lung cancer in women and in nonsmokers, adenocarcinoma forms in the mucus-producing glands of the lungs.
  • Bronchioalveolar carcinoma. This type of lung cancer is a rare type of adenocarcinoma that forms near the lungs’ air sacs.
  • Large-cell undifferentiated carcinoma. A rapidly growing cancer, large-cell undifferentiated carcinomas form near the outer edges or surface of the lungs.

Small Cell Lung Cancer (SCLC) is characterized by small cells that multiply quickly and form large tumors that travel throughout the body. Almost all cases of SCLC are due to smoking.

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. Among those who smoke Two or More Packs of cigarettes per day, one in seven will die of Lung Cancer. Pipe and cigar smoking can also cause Lung Cancer.
  • 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.
  • Asbestos fibers. Asbestos fibers are silicate fibers that can persist for a lifetime in lung tissue following exposure to asbestos. The workplace is a common source of exposure to asbestos fibers, as asbestos was widely used in the past as both thermal and acoustic insulation. Today, asbestos use is limited or banned in many countries
  • Radon gas. Radon gas is a natural, chemically inert gas that is a natural decay product of uranium. Uranium decays to form products, including radon, that emit a type of ionizing radiation. Radon gas is a known cause of Lung Cancer, with an estimated 12% of lung-cancer deaths attributable to radon gas
  • Other factors, such as individual Genetic Susceptibility, may play a role in the causation of Lung Cancer. Numerous studies have shown that Lung Cancer is more likely to occur in both smoking and nonsmoking relatives of those who have had lung cancer than in the general population.
  • Lung diseases. The presence of certain diseases of the lung, notably Chronic Obstructive Pulmonary Disease (COPD), is associated with an increased risk.
  • Prior history of lung cancer. Survivors of Lung Cancer have a greater risk of developing a second lung cancer than the general population has of developing a first lung cancer.
  • Air pollution. Air pollution from vehicles, industry, and power plants can raise the likelihood of developing lung cancer in exposed individuals.
  • The history and physical examination may reveal the presence of symptoms or signs that are suspicious for lung cancer. In addition to asking about symptoms and risk factors for cancer development such as smoking, doctors may detect signs of breathing difficulties, airway obstruction, or infections in the lungs.
  • The Chest X-Ray is the most common first diagnostic step when any new symptoms of lung cancer are present.
  • 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.
  • Magnetic Resonance Imaging (MRI) Scans may be appropriate when precise detail about a tumor’s location is required. The MRI technique uses magnetism, radio waves, and a computer to produce images of body structures.

Symptoms and Signs of Lung Cancer

Correlation between smoking and lung cancer in...
Correlation between smoking and lung cancer in US males, showing a 20-year time lag between increased smoking rates and increased incidence of lung cancer. (Photo credit: Wikipedia)
  • A new persistent cough or worsening of an existing Chronic Cough. ,
  • Blood in the sputum.
  • persistent Bronchitis or repeated respiratory infections.
  • Chest pain.
  • Unexplained Weight Loss and/or fatigue.,
  • Breathing difficulties such as shortness of breath or wheezing.

Diagnose Of Lung Cancer

  • Positron Emission Tomography (PET) scanning is a specialized imaging technique that uses short-lived radioactive drugs to produce three-dimensional colored images of those substances in the tissues within the body. While CT scans and MRI scans look at anatomical structures, PET scans measure metabolic activity and the function of tissues. PET scans can determine whether a tumor tissue is actively growing and can aid in determining the type of cells within a particular tumor.
  • Bone Scans are used to create images of bones on a computer screen or on film. Doctors may order a bone scan to determine whether a Lung Cancer has metastasized to the bones.
  • Sputum cytology: The diagnosis of lung cancer always requires confirmation of malignant cells by a pathologist, even when symptoms and X-ray studies are suspicious for lung cancer. The simplest method to establish the diagnosis is the examination of sputum under a microscope. If a tumor is centrally located and has invaded the airways, this procedure, known as a sputum cytology examination, may allow visualization of tumor cells for diagnosis. This is the most risk-free and inexpensive tissue diagnostic procedure, but its value is limited since tumor cells will not always be present in sputum even if a cancer is present.

Treatment of Lung Cancer

Treatment for Lung Cancer can involve Surgical Removal of the cancer, Chemotherapy, or Radiation Therapy, as well as combinations of these treatments. The decision about which treatments will be appropriate for a given individual must take into account the location and extent of the tumor as well as the overall health status of the patient.

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