About Lung Cancer

Lung cancer is the U.S.’s top cancer killer, claiming approximately 160,000 lives per year. It is a devastating disease that can afflict anyone, regardless of smoking history, gender, or ethnicity.

While colon, breast, and prostate cancer all have reliable early detection tests, lung cancer does not. Currently, only 17% of people diagnosed with lung cancer survive five years post-diagnosis, a percentage significantly lower than that for each of these other cancers. And with early detection, there is hope.

With the support of our donors, LUNGevity funds research to develop early detection methods and targeted therapies for lung cancer.

The Statistics

  • Lung cancer is the leading cause of cancer death, regardless of gender or ethnicity.
  • One in 14 people will be diagnosed with lung cancer, and it  kills more people than colorectal, breast and pancreatic cancers combined.
  • Lung cancer kills almost twice as many women as breast cancer, and almost three times as many men as prostate cancer.
  • About 60% of all new lung cancer diagnoses are among people who have never smoked or are former smokers.
  • Lung cancer accounts for 14% of all new cancer diagnoses but 27% of all cancer deaths.

Lung Cancer Basics

Lungs are a key part of the respiratory system. When we inhale, air enters our nose or mouth and goes down our trachea. The trachea branches into two sets of bronchial tubes, each one taking air to a lung. Once inside the lung, the air makes its way into smaller and smaller branched tubes, called bronchi, until it finally enters the aveoli, small balloon-like sacs. Within these sacs, materials such as carbon dioxide and oxygen are transferred between the blood stream and the air.

What is lung cancer?

Almost any cell in the body can become cancerous. Cancer, of any kind, is caused by a cell that has developed mutations that cause the cell to stop regulating its growth. When such a renegade cell begins to proliferate out of control, it forms a lump known as a tumor. These tumors draw on the body’s resources and often manipulate the blood vessels and other infrastructure for their benefit without any regard to the effect on the surrounding healthy tissue. Too often, these tumors are in the lungs and respiratory tract, and we refer to them as lung cancer.

Are there different types of lung cancer?

Although emerging findings are starting to reveal that lung cancer is much more complicated than this, lung cancer is generally discussed in terms of the two most common types: small cell and non-small cell lung cancer.

Small cell lung cancer is closely linked to smoking and second-hand smoke. This type of tumor (found in approximately 13% of lung cancer patients) is made of cells that are relatively small in size. Though the cells are small, they divide and multiply quickly to form large tumors. In fact, the size and speed of these cancer cells are part of what makes them so dangerous. They can quickly spread to other parts of the body, including the lymph nodes and bones.

Almost all the other lung cancers (approximately 87% of lung cancer diagnoses) are referred to as non-small cell lung cancer. This type of cancer multiplies and spreads more slowly than small cell lung cancer. As our understanding of lung cancer has grown, we have been able to divide these tumors into three main subtypes, mainly based on where the original cancer cell was located. But because the approaches for diagnosis, staging, prognosis and treatment are similar, they are often discussed together. The three main subtypes are:

  • Squamous cell carcinoma is a tumor that begins in squamous cells, the thin, flat cells (resembling fish scales) that line the passages of the respiratory tract.
  • Adenocarcinomas are tumors that originated in the cells lining the lungs. Before transformation into tumor cells, these cells have the enhanced ability to secrete compounds into their surrounding tissue. Therefore, once the cells become cancerous, this enhanced secretory ability could be used to increase tumor growth.
  • Large cell carcinomas, representing approximately 5-10% of lung cancer diagnoses, are often diagnosed by default, when all other possibilities have been excluded. These tumors do not display diagnostic features to help clinicians characterize them prior to biopsy.

A much rarer type of lung cancer is called carcinoid cancer, and it is a type of neuroendocrine tumor. This is a slow-growing tumor found mostly in the gastrointestinal system, but it can also appear in the lungs. Because these tumors originate in hormone-producing cells, the carcinoid tumors can secrete excess serotonin, bradykinin, histamine, and prostaglandins. Elevated levels of these substances can sometimes result in a diverse set of symptoms called carcinoid syndrome.


Do you have lung cancer?

Unfortunately, it is very difficult to know if you have lung cancer in the early stages of disease when it is the most treatable. Typically lung cancer is asymptomatic until the disease has progressed to a later stage.

The following symptoms could be indicators of lung cancer:

  • a cough that gets worse or does not go away
  • breathing trouble, such as shortness of breath
  • constant chest pain
  • coughing up blood
  • a hoarse voice
  • frequent lung infections, such as pneumonia
  • feeling very tired all the time
  • weight loss with no known cause

Usually these symptoms are related to health issues other than lung cancer. If you feel you have some of these symptoms, you should visit a medical professional as soon as possible.


How do doctors diagnose lung cancer?

Unlike breast, colon and prostate cancers, there is not yet a reliable way to detect lung cancer in its earliest and most treatable stage.

However, once a patient is suspected of having lung cancer, there are many different tests and procedures, such as imaging, biopsy and laboratory testing, that an oncologist uses to identify and diagnose lung cancer.

Imaging tests, such as CT (computed tomography or CAT) scans, MRI (magnetic resonance imaging) scans, and PET (positron emission tomography) scans are commonly used to show the location and size of the cancer. In addition, these scans can show what the tumor looks like and help determine whether the cancer has spread to other parts of the body.

Biopsies of the lung cancer can be done using a needle or through a more invasive surgical procedure. In the case of a needle biopsy, the oncologist usually will get a pathology report that includes information about the tumor’s size, the type of lung cancer and the grade of the tumor. The surgical option can give further information about the appearance and size of the tumor. Plus, it gives the oncologist the opportunity to inspect lymph nodes and other organs for signs of cancer.

Laboratory tests can help doctors determine whether a patient has lung cancer and the extent of the disease.

Conducting tests on the mucus and/or blood cells coughed up by patients, called sputum cytology, helps to determine whether a patient has lung cancer and can identify the type of lung cancer. However, it does not show the extent of the disease. So, if a patient is found to have sputum that is positive for lung cancer, additional tests are usually required.

Other laboratory tests on urine, blood, feces etc. can provide critical information about the functionality of other organs in the body. This can help to guide doctors in determining the extent to which the cancer has spread.

Lung Cancer Staging

The severity of lung cancer disease is often gauged by the stage of the tumor, but with so many numbers and letters involved it can seem daunting. Here are simple charts to help clarify the meaning of all that technical jargon.

What is staging?

Staging is a careful attempt to find out whether the cancer has spread, and if so, to what parts of the body. Lung cancer spreads most often to the lymph nodes, brain, bones, liver and adrenal glands.

When cancer spreads from its original place to another part of the body, the new tumor has the same kind of cancer cells and the same name as the original cancer. For example, if lung cancer spreads to the liver, the cancer cells in the liver are actually lung cancer cells. The disease is called “metastatic lung cancer,” not “liver cancer,” and it is treated as lung cancer, not liver cancer. Doctors call the new tumor "distant" or “metastatic” disease.

Why is staging tumors important?

Staging is a way for doctors to describe the extent of the disease. Typically, these stages are used when developing treatment options and conducting clinical trials. So, often the stage of disease helps the doctor to determine which treatment options are best suited for individual patients.

Are all lung cancer tumors staged the same way?

No. The two main types of lung cancer—small cell and non-small cell—are staged very differently. Therefore, the types of staging information you get from your oncologist will depend on which type of lung cancer you have.

How do we stage small cell lung cancer?

Oncologists describe small cell lung cancer using two stages, and each stage has a unique set of treatment options.

“Limited stage”—this means the cancer is found only in one lung and its nearby tissues.

“Extensive stage”—this means the cancer is found in chest tissues outside of the originally diseased lung. It can also mean the cancer is found in distant organs.

How do we stage non-small cell lung cancer?

The staging language for non-small cell is more complicated. An oncologist will typically use a number and a letter to describe the cancer based on the size of the lung tumor and whether or not the cancer has spread to the lymph nodes or to other tissues (such as, “You have stage 2B lung cancer”). Here are the definitions of these stages to help you understand what those letters and numbers (sometimes written as Roman numerals) mean.

  • Occult stage: Lung cancer cells are found in sputum or in a sample of water collected during bronchoscopy, but a tumor cannot be seen in the lung.
  • Stage 0: Cancer cells are found only in the innermost lining of the lung. The tumor has not grown through this lining. A stage 0 tumor is also called carcinoma in situ. The tumor is not an invasive cancer.
  • Stage IA: The lung tumor is an invasive cancer. It has grown through the innermost lining of the lung into deeper lung tissue. The tumor is no more than 3 centimeters across (less than 1¼ inches). It is surrounded by normal tissue and the tumor does not invade the bronchus. Cancer cells are not found in nearby lymph nodes.
  • Stage IB: The tumor is larger or has grown deeper, but cancer cells are not found in nearby lymph nodes. The lung tumor is one of the following:
    • The tumor is more than 3 centimeters across.
    • It has grown into the main bronchus.
    • It has grown through the lung into the pleura.
  • Stage IIA: The lung tumor is no more than 3 centimeters across. Cancer cells are found in nearby lymph nodes.
  • Stage IIB: The tumor has one of the following characteristics:
    • Cancer cells are not found in nearby lymph nodes, but the tumor has invaded the chest wall, diaphragm, pleura, main bronchus, or tissue that surrounds the heart.
    • Cancer cells are found in nearby lymph nodes, and one of the following:
      • The tumor is more than 3 centimeters across.
      • It has grown into the main bronchus.
      • It has grown through the lung into the pleura.
  • Stage IIIA: The tumor may be any size. Cancer cells are found in the lymph nodes near the lungs and bronchi, and in the lymph nodes between the lungs but on the same side of the chest as the lung tumor.
  • Stage IIIB: The tumor may be any size. Cancer cells are found on the opposite side of the chest from the lung tumor or in the neck. The tumor may have invaded nearby organs, such as the heart, esophagus, or trachea. More than one malignant growth may be found within the same lobe of the lung. The doctor may find cancer cells in the pleural fluid.
  • Stage IV: Malignant growths may be found in more than one lobe of the same lung or in the other lung. Or cancer cells may be found in other parts of the body, such as the brain, adrenal gland, liver, or bone.

Reducing Your Risk of Lung Cancer

While doctors cannot always explain why one person develops lung cancer and another does not, there are certain risk factors that can increase a person’s chance of developing lung cancer.

These factors can increase your risk of lung cancer:

  • Tobacco smoke: Tobacco smoke causes most cases of lung cancer. It's by far the most important risk factor for lung cancer. Harmful substances in smoke damage lung cells and make the lungs more vulnerable to other cancer-causing environmental factors. Smoking cigarettes, pipes, or cigars can cause (or accelerate) lung cancer. Even secondhand smoke can cause lung cancer in nonsmokers. The more a person is exposed to smoke, the greater the risk of lung cancer.
  • Radon: Radon is a radioactive gas that you cannot see, smell, or taste. It forms naturally in soil and rocks. People who work in mines may be exposed to radon. In some parts of the country, radon is found in houses. Radon damages lung cells, and people exposed to radon are at increased risk of lung cancer. The risk of lung cancer from radon is even higher for smokers.
  • Asbestos and other substances: People who have certain jobs (such as those who work in the construction and chemical industries) have an increased risk of lung cancer. Exposure to asbestos, arsenic, chromium, nickel, soot, tar, and other substances can cause lung cancer. The risk is highest for those with years of exposure. The risk of lung cancer from these substances is even higher for smokers.
  • Air pollution: Air pollution may slightly increase the risk of lung cancer. The risk from air pollution is higher for smokers.
  • Family history of lung cancer: People with a father, mother, brother, or sister who had lung cancer may be at slightly increased risk of the disease, even if they don't smoke.
  • Personal history of lung cancer: People who have had lung cancer are at increased risk of developing a second lung tumor.
  • Age over 65: Most people are older than 65 years when diagnosed with lung cancer.

If you are at increased risk of developing lung cancer, talk to your doctor. Your doctor may be able to suggest ways to reduce your lung cancer risk.

Early Detection of Lung Cancer

Detecting lung cancer early is the best way to survive the disease. Unfortunately, because the disease is typically asymptomatic until it is in the late stages, early detection is uncommon. In fact, 79% of lung cancers are diagnosed once the tumor has spread beyond the original tumor site.

LUNGevity is taking steps to address this issue. We are funding research to quickly develop effective methods to detect lung cancer early, so we can find it, treat it and live. You can help—learn how.


Click here for sources.