Nearly 170,000 Americans are diagnosed with lung cancer each year. While cigarette smoking is the main cause, anyone can develop lung cancer.

The lungs contain many different types of cells. Most cells in the lung are epithelial cells. These cells line the airways and produce mucus, which lubricates and protects the lung. The lung also contains nerve cells, hormone-producing cells, blood cells, and structural or supporting cells.

There are two major types of lung cancer. Non-small cell lung cancer (the most common) is believed to arise from epithelial cells. Small cell lung cancer is believed to arise from nerve cells or hormone-producing cells. The term “small cell” refers to the size and shape of the cancer cells seen under the microscope.

Lung cancer begins when cells in the lung grow out of control, and form a tumor. A lung tumor can begin anywhere in the lung. Once a lung tumor begins to grow, it may or may not shed cancer cells. These cells can travel through tiny tubes in the lung called lymphatic vessels, which drain into collecting stations called lymph nodes located in the lungs and the center of the chest. Cancer cells can also travel through blood vessels to distant sites in the body, where they can form other tumors. This process is known as metastasis.

Not all lung tumors metastasize. In general, small cell lung cancers are more likely to metastasize than non-small cell lung cancers, so the two types of lung cancer are treated in different ways. Lung cancer is always treatable, no matter the size, location, or if the cancer has spread.

Lung cancer is a malignant tumor that grows in one or both lungs. Lung cancer usually forms from cells that line the airways and nearby glands because these cells are what come in contact with the air we breathe which may contain carcinogens. In lung cancer, the changing of normal cells into cancerous cells usually happens over a period of years.

What causes lung cancer?

There are several factors that can contribute to the development of lung cancer. Smoking is the number one cause of lung cancer. While smoking is an important risk factor in developing lung cancer, there are many people with lung cancer who have never smoked. Other factors that contribute to lung cancer include the following:

Exposure to chemicals in the air such as asbestos and radon

* Lung diseases that can block airflow to the lungs such as chronic obstructive pulmonary disease (COPD) or tuberculosis

* Genetics - people with a relative who had lung cancer are at higher risk for developing lung cancer

* Age - lung cancer occurs more often in people over 65 years of age

Cigarette smoke contains at least 43 different carcinogens (cancer-causing chemicals). It has been associated with various cancers including lung, esophagus, mouth, stomach, pancreas, and liver, to name just a few. Smoking accounts for at least 30% of all cancer-related deaths and 87% of lung cancer deaths. Approximately 50% of new lung cancers are diagnosed in former smokers. The risk of lung cancer increases with an increase in the total number of cigarettes smoked, referred to as pack-years (number of packs smoked per day times the number of years smoked). The use of cigar and pipe tobacco also increases the risk of developing cancer, but the risk is not as high as with cigarettes.

Secondhand smoke also contains carcinogens, and each year in the US between 5,000 and 10,000 people are diagnosed with lung cancer resulting from breathing secondhand smoke.

Quitting smoking decreases the risk of developing lung cancer. Ten years after quitting, the risk decreases by half. Although smoking cessation lowers this risk of developing lung cancer, the risk never decreases to the level of people who have never smoked. Recent findings for smokers who have been diagnosed with lung cancer suggest that those who quit smoking during their lung cancer treatment may live longer than those who continue to smoke during treatment.

It’s never too late to quit smoking! If you currently smoke and would like to quit, talk to your doctor about the different options to help you stop smoking.

LUNG CANCER SYMPTOMS

Some of the symptoms of lung cancer are similar to symptoms of other common illnesses. So, it’s important for your doctor to perform a thorough physical examination and to know your medical history. Your doctor will consider your age, smoking history, and diseases or conditions that you and your family members may have. Your doctor will also need to know if you’ve been exposed to any harmful chemicals. All of these things will help to determine the next steps.

The most common symptom of lung cancer is cough; it occurs in over 50% of people with lung cancer. The tumor causes irritation to the lungs and airway tissue, resulting in cough. Other common symptoms of lung cancer are chest pain, shortness of breath (dyspnea), and wheezing. About 30% of people with lung cancer will cough up blood, called hemoptysis; you should call your doctor immediately if this happens. If the tumor grows larger, it can press on nearby organs and bones. When this happens, symptoms may include bone pain, chest pain, hoarseness, cough, shortness of breath, swelling of the face or arms, and/or a build up of fluid around the outside of the lungs, also called pleural effusion.

Some symptoms are caused by the cancer spreading to other parts of the body (the lung cancer has metastasized). Symptoms from lung cancer metastases depend on where the cancer has spread. If the lung cancer has spread to the brain or spinal cord, you may experience headaches, nausea, vomiting, weakness, tiredness, or seizures. If the lung cancer has spread to the bones, you may feel bone pain. If the cancer has spread to the liver, you may have right-sided abdominal pain and jaundice. There are also some general symptoms of lung cancer like weight loss, fatigue, and loss of appetite. If you have been diagnosed with lung cancer and you develop any of these or other new symptoms, you should let your doctor know.