Lung cancer is, far and away, the leading cause of cancer death in the United States for both men and women, and claims more lives per year than all colon, prostate, ovarian and breast cancers combined.  People who smoke are at greater risk for lung cancer, although those who have never smoked may also have this cancer. It increases with the number of cigarettes and the amount of time you have smoked. If you quit smoking, even after you have smoked for many years, you can significantly reduce your chances of getting lung cancer.
What Causes it, And How It Is Caused
Smoking causes most cases of lung cancer, both in direct smokers and in secondhand smoke. However, lung cancer can also occur in people who have never in their life smoked and in those who have never had a prolonged exposure to secondhand smoke. In those very unfortunate -and thankfully extremely rare- cases, there may not be an obvious cause of lung cancer.
Professionals, doctors and such hold the theory that tobacco causes lung cancer by damaging the cells that surround the lungs.  When you inhale cigarette smoke, which is full of substances that cause cancer known as carcinogens, changes occur in lung tissue almost immediately. At first, the body can repair this damage quite easily and effectively. But, with each repeated exposure, the normal cells that surround the lungs become more and more damaged and, over time, said damage will then cause the cells to begin to act abnormally, which eventually will pave the way for cancer to develop in the lungs.
Symptoms, What to Look Out for And When to Consult Your Doctor
Lung cancer usually produces no signs or symptoms in the earliest stages. The signs and symptoms of this condition usually occur only when the disease is in its advanced stage. Signs and symptoms of lung cancer can be:
- A recent cough that won’t go away
- Coughing up blood, even in small amounts
- Lack of air
- Chest pain
- Slimming down without proposing it
- Bone pain
As for when to take action, ask for a doctor’s consultation if any of the symptoms mentioned above are constant, or just overall any signs that may give you a red flag and alert you that something might not be right. If you smoke and have not been able to quit, ask for a doctor’s appointment, as he or she can recommend strategies to stop smoking, such as therapy, medication, and nicotine replacement therapy. 
How It Is Diagnosed
A doctor will ask general questions about your health status, personal medical history (tobacco use, symptoms) and sometimes even family members. They will perform a physical examination by monitoring your lungs, and in addition to that, you may be asked to undergo other complementary studies, including a blood test and a chest X-ray. With these tests, a diagnosis will be obtained. First, the presence of a cancer will be ruled out or confirmed, and then its extension or stage will be determined. Throughout the diagnostic process you may be subjected to different tests. Some of these are:
- Sputum Cytology: It is a matter of analyzing the type of cells contained in the patient’s expectoration, since when coughing, cells are detached and dragged from the bronchial tubes, which in some cases may be cancerous.
- CT (Computerized Axial Tomography): Allows you to view the internal organs through the images generated by a computer connected to an X-ray machine This link will open in a new window. You will probably be lying on a stretcher and the scanner will go through the scan area. Sometimes it can be complemented with contrasts, for which a substance will be injected to make the image of the lung structures stand out.
- Thoracentesis: Consists of analyzing the type of cells contained in the pleural fluid. For its extraction, a long needle will be used to gain access to the pleural cavity.
- Thoracotomy: Consists of a wide incision in the chest to remove lymph nodes or tissues.
- Bronchoscopy: A technique that consists of introducing a flexible tube with a video camera through the nose or mouth, through the throat, into the bronchi to examine the lungs and airways. It helps to confirm the diagnosis since tissue samples (biopsy), or cells can be removed with a needle, brush, or by washing. Because the procedure, although short, can sometimes be uncomfortable, you will be given a sedative anesthetic.
How It Is Treated
Surgery: With the removal of the entire lobe where the tumor is located, is the primary treatment for patients with early-stage cancer who are in good general health. The goal of surgery is to completely remove all the tumor cells and thus cure the disease. Some of the more common types are:
- Lobectomy: the removal of an entire lobe of the lung, is an accepted procedure for removing lung cancer when the lungs are functioning well. The mortality risk is less than three to four percent and tends to be higher in older patients.
- Sublobar resection: If lung function prohibits a lobectomy, or a tumor is very small, a sublobar resection may be performed in which a small cancer confined to a limited area may be removed with a small portion of the surrounding lung tissue.
- Mediastinoscopy: Mediastinoscopy is done through a small incision in the lower neck, above the breastbone, and is used to sample the lymph nodes in the center of the chest (mediastinum).
Radiation therapy: delivers high-energy x-rays that can destroy cancer cells. It has many uses in lung cancer, such as a primary treatment to reduce the size of the tumor before surgery, after surgery to remove any cancer cells that may have remained in the treated area, and to treat lung cancer that has spread to the brain or other parts of the body or to relieve symptoms.
Chemotherapy: involves drugs that are toxic to cancer cells. These drugs are usually given by direct injection into the vein or through a catheter inserted into a large vein.
However, remember that the best treatment available is prevention. Not smoking at all to being with is best but if it cannot be avoided consider things such as dieting and periodical exercise, as well as tobacco replacements like nicotine patches and lozenges.