Lung Cancer

LUNG CANCER QUICK FACTS

  • Lung cancer is the second most common cancer in both men and women (skin cancer is the most common).
  • Lung cancer accounts for about 14 percent of all new cancers.
  • This year, 116,470 men and 109,690 women will be newly diagnosed with lung cancer in the United States.
  • About 160,340 people will die from lung cancer in the United States this year.
  • About two out of three people diagnosed with lung cancer are 65 or older.
  • Fewer than 2 percent of all cases are found in people younger than 45.
  • The chance that a man will develop lung cancer in his lifetime is about 1 in 13 and for a woman, 1 in 16.*
  • African American men are about 40 percent more likely to develop lung cancer than Caucasian men. The rate is about the same in African American women and in Caucasian women.
  • The lung cancer rate has been dropping among men for many years and is just beginning to drop in women after a long period of rising.
  • Although lung cancer is a serious illness, some people are cured. More than 350,000 people alive today have been diagnosed with lung cancer at some point. With diagnosis, it’s important to seek support.

*these numbers include both smokers and non-smokers. For smokers the risk is much higher.

 

WHAT IS LUNG CANCER AND HOW DOES IT START?

All cells in the body contain the genetic material called deoxyribonucleic acid (DNA). Every time a mature cell divides into two new cells, its DNA is exactly duplicated. The cells are copies of the original cell, identical in every way. In this way, our bodies continually replenish themselves. Old cells die off and the next generation replaces them.

A 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.

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. When a cell with a genetic mutation divides, it passes along its abnormal genes to the two new cells, which then divide into four cells with errors in their DNA and so on. With each new mutation, the lung tissue cell becomes more mutated and may not be as effective in carrying out its function as a lung cell. At a later stage of disease, some cells may travel away from the original tumor and start growing in other parts of the body. This process is call metastasis and the new distant sites are referred to as metastases.

Exposure to both primary and secondhand smoke increase the risk of lung cancer. According to the Surgeon General’s Report on the effects of secondhand smoke, nonsmokers exposed to secondhand smoke at home or at work increase their risk of developing lung cancer by 20 percent to 30 percent. Secondhand smoke also increases the risk of heart disease and other ailments.

Other environmental substances or exposures that can increase the risk of developing lung cancer include:

  • Asbestos are tiny, hair-like fibers found in some types of rock. Asbestos is a natural mineral that is fireproof and insulating and was used in building construction materials and in some manufacturing processes. When asbestos is inhaled, the fibers can irritate the lung and may eventually cause lung disease. People who smoke and are exposed to asbestos have a higher risk of developing lung cancer. Fortunately, professional protective breathing equipment can reduce the risk of breathing in asbestos fibers for those who work with or around asbestos. (Asbestos has NOT been banned from use in the United States and is still regularly used.)
  • Radon is an odorless gas released by some soil and rocks that contain uranium. Some homes may have high levels of radon, especially on the lower levels, because they are built on soil that naturally contains radon. You can purchase Environmental Protection Agency-approved kits in hardware stores to measure the amount of radon in your home.
  • Industrial substances can include arsenic, uranium, beryllium, vinyl chloride, nickel chromates, coal products, mustard gas, chloromethyl ethers, gasoline, and diesel exhaust.
  • Radiation exposure such as X-rays to the chest area can increase the risk of lung cancer, especially in people who smoke.
  • Air pollution can contain trace amounts of diesel exhaust, coal products, and other industrial substances.
  • Tuberculosis can cause scarring of lung tissue, which can be a risk factor for developing lung cancer.
  • Genetics can also play a role in the development of lung cancer through inherited or environmentally-acquired gene mutations.
  • Military service may have presented both veterans and active-duty personnel with exposures to industrial substances, asbestos bearing materials, and air pollution, as well as exposure to tactical chemicals (Agent Orange, for example). In addition, military past and current military personnel present with significantly higher smoking rates.

 

TYPES OF LUNG CANCER AND WHAT STAGES MEAN

There are two major types of lung cancer, non-small cell lung cancer (NSCLC) and small cell lung cancer (SCLC). Staging lung cancer is based on whether the cancer is local or has spread from the lungs to the lymph nodes or other organs. Because the lungs are large, tumors can grow in them for a long time before they are found. Even when symptoms—such as coughing and fatigue—do occur, people think they are due to other causes. For this reason, early-stage lung cancer (stages I and II) is difficult to detect.

Non-Small Cell Lung Cancer

Non-small cell lung cancer accounts for about 85 percent of lung cancers and includes:

  • Adenocarcinoma, the most common form of lung cancer in the United States among both men and women;
  • Squamous cell carcinoma, which accounts for 25 percent of all lung cancers;
  • Large cell carcinoma, which accounts for about 10 percent of NSCLC tumors.

Stages of Non-Small Cell Lung Cancer:

Stage I: The cancer is located only in the lungs and has not spread to any lymph nodes.

Stage II: The cancer is in the lung and nearby lymph nodes.

Stage III: Cancer is found in the lung and in the lymph nodes in the middle of the chest, also described as locally advanced disease. Stage III has two subtypes:

If the cancer has spread only to lymph nodes on the same side of the chest where the cancer started, it is called stage IIIA.

If the cancer has spread to the lymph nodes on the opposite side of the chest, or above the collar bone, it is called stage IIIB.

Stage IV: This is the most advanced stage of lung cancer, and is also described as advanced disease. This is when the cancer has spread to both lungs, to fluid in the area around the lungs, or to another part of the body, such as the liver or other organs.

Small Cell Lung Cancer

Small cell lung cancer accounts for the remaining 15 percent of lung cancers in the United States. They tend to grow more quickly than NSCLC tumors. Usually, SCLC is more responsive to chemotherapy than NSCLC.

Stages of Small Cell Lung Cancer:

Limited stage: In this stage, cancer is found on one side of the chest, involving just one part of the lung and nearby lymph nodes.

Extensive stage: In this stage, cancer has spread to other regions of the chest or other parts of the body.

The American Joint Commission on Cancer implemented a more detailed staging system in which the stages of small cell lung cancer are described using Roman numerals and letters (for example, Stage IIA). This is the same method that is used for non-small cell lung cancer in describing the growth and spread of the cancer.

 

PREVENTATIVE SCREENING FOR LUNG CANCER

Most lung cancers are first diagnosed based on symptoms. Symptoms of lung cancer are not very specific and generally reflect damage to the lungs’ ability to function normally. The most common symptoms are a worsening cough that will not go away, and chest discomfort. Other symptoms include shortness of breath, spitting up small amounts of blood, unexplained weight loss, back pain, loss of appetite, and a general fatigue.

Unlike mammography for breast cancer or colonoscopy for colon cancer, a widely accepted screening tool for early-stage lung cancer has not been available until recently. Regular chest X-rays are not reliable enough to find lung tumors in their earliest stages, when many doctors believe the tumors are at their smallest and most curable state.

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.

In addition to this screening procedure, there is current research looking into identifying less complicated and expensive ways to screen for lung cancer, including analyses of breath and saliva.