Lung Cancer

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What is lung cancer?

Lung cancer is a common cancer of the respiratory system that occurs when there is an uncontrolled growth of abnormal cells lining the air passages of the lung. Lung cancer is the most commonly diagnosed malignancy in both men and women, according to the National Institutes of Health. The main cause of lung cancer is smoking.

Women who have never smoked may be more at risk of developing lung cancer than men who have never smoked. In fact, 47% of cases of lung cancer occur in women, and one in five women with lung cancer has never smoked. In contrast, only one in 10 men with lung cancer has never smoked, according to the National Lung Cancer Partnership.

While not usually noticed until later in the disease, lung cancer symptoms include fatigue, chest pain, difficulty breathing, and worsening and persistent cough, which may bring up bloody sputum. Lung cancer treatment advances have improved the prognosis and survival rates for many people with this type of cancer.

Seeking regular medical care offers the best chances of discovering lung cancer in its earliest, most curable stage. If you have lung cancer, following your treatment plan may help reduce your risk of some complications of lung cancer.

Lung cancer is a highly preventable cancer because the majority of cases are caused by smoking. Quitting smoking greatly reduces your risk of lung cancer. Diagnosing lung cancer in its earliest stage provides the best hope for successful treatment and a cure. If you currently smoke or have a history of smoking, talk with your doctor about testing for lung cancer.

What are the types of lung cancer?

Lung cancer is the presence of malignant cells that begin in the lung and form cancerous tumors. Malignant lung cells grow much faster than normal lung cells. Because of this abnormal growth, lung cancer can spread throughout one or both lungs and eventually the rest of the body.

There are three main types of lung cancer:

  • Small cell lung cancer starts in cells lining the bronchial tube of the lung and grows faster than other lung cancer types.
  • Lung carcinoid tumor is lung cancer that starts in neuroendocrine cells within the lung; it also grows slow.

What are the stages of lung cancer?

The type and stage of lung cancer helps doctors determine what treatment to use. Non-small cell lung cancer (NSCLC) is the most common type, accounting for about 85% of diagnoses. Lung cancer staging is very complex.

This is a simplified view of NSCLC stages:

  • Stage 0 lung cancer is only in the top-most layer of cells lining the airways.
  • Stage I (1) lung cancer remains in the lung and has not spread to any lymph nodes.
  • Stage II (2) lung cancer may extend into the chest wall and lymph nodes near the lung, and there may be two or more separate tumor masses in the same lung. It has not spread to distant sites in the body.
  • Stage III (3) lung cancer may have spread to nearby lymph nodes or to other organs in the chest, and there may be two or more tumors in the same lung or partial blocking of an airway (bronchus). It has not spread to distant body sites.
  • Stage IV (4) lung cancer is growing extensively beyond the lung (to the other lung or organs in the chest, such as the esophagus) and may have reached distant lymph nodes and body sites, such as the brain. Another term for stage 4 lung cancer is metastatic lung cancer.

Small cell lung cancer is divided into two stages: limited stage in which cancer is in one side of chest, and extensive stage, which is metastatic small cell lung cancer.

Lung carcinoid tumor is divided into the resectable stage in which surgical removal of the tumor may cure the patient, and the unresectable stage, which may not be resectable or it requires more than surgery, such as chemotherapy and radiation treatment.

What are the symptoms of lung cancer?

Lung cancer often produces no symptoms in its earliest stages, when it is most treatable. Symptoms may not occur for a decade or more after lung cancer has developed. When symptoms do occur, they often indicate that lung cancer has progressed to an advanced, less curable stage.

Symptoms of lung cancer include:

  • A cough that gets more severe over time
  • Chest pain
  • Difficulty breathing, shortness of breath, or wheezing
  • Long-term cough
  • Weight loss

What causes lung cancer?

Lung cancer is a highly preventable form of cancer. Lung cancer can be caused by:

  • Smoking, including pipes, cigarettes and cigars
  • Exposure to secondhand smoke
  • Exposure to airborne carcinogens (substances that cause cancer), such as radon and asbestos
  • Inherited gene mutations, which increase the risk of developing lung cancer
  • Metastasis of cancer from other areas in the body, such as the breast, prostate or bone

Smoking and Secondhand Smoke

Cigarette smoking and exposure to secondhand smoke cause about 90% of all lung cancer cases, and nearly all small cell lung cancers. Exposure to smoke damages the cells that line the lungs. Over time, these abnormal cells multiply and form malignant tumors, which crowd out and destroy healthy cells.

Exposure to Cancer Causing Agents

Lung cancer can develop in people who do not have a history of smoking or exposure to secondhand smoke. Exposure to these cancer causing agents (carcinogens) can increase your risk for lung cancer:

  • Radon is a radioactive gas present at very low levels in soil, rock and air, but it can become more concentrated inside poorly ventilated buildings and water sourced from deep wells.
  • Hazardous chemicals including working with asbestos, uranium, some petroleum products, and elements used in metal production, such as arsenic, cadmium, chromium, and nickel
  • Air pollution including exhaust smoke, and other particle pollution

Inherited gene mutations

It’s possible for people to inherit gene mutations that increase the risk of developing cancer, but heredity is not thought to play a significant role in lung cancer.

Metastasis of another cancer

Cancer of the lung can also be caused by metastasis of cancer from areas in the body. The types of cancer most likely to spread to the lungs are breast, prostate or bone. Where the cancer started is the primary cancer. When the primary cancer spreads to the lung, the lung cancer is called secondary cancer because the lungs are the secondary location.

What are the risk factors for lung cancer?

A number of factors increase your chances of developing lung cancer. The biggest risk factor is smoking; the more you smoke and the earlier you start smoking, the greater your risk of developing lung cancer. If you smoke, quitting can greatly reduce your risk of developing lung cancer, even if you have been a heavy smoker for many years.

Not all people with risk factors will develop lung cancer, but significant risk factors for lung cancer include:

  • Smoking cigarettes, cigars or pipe
  • Exposure to carcinogens (substances that cause cancer) in the air, such as radon and asbestos
  • Exposure to secondhand smoke
  • Genetic factors tied to lung cancer. Some people inherit gene mutations that increase the risk of developing lung cancer. These mutations can increase the risk of lung cancer in both smokers and nonsmokers. It’s also possible to acquire, or develop mutations in certain genes that make cancer more likely.

How do you prevent lung cancer?

Lung cancer is a highly preventable form of cancer. You can significantly lower your risk of lung cancer by:

  • Not smoking
  • Avoiding exposure to carcinogens in the air (substances that cause cancer), such as radon and asbestos. Precautions include wearing an appropriate protective mask when working around carcinogens, testing your home or workplace for radon, and installing a radon mitigation system if needed.
  • Avoiding exposure to secondhand smoke

How do you diagnose lung cancer?

In many cases, a patient’s symptoms lead to lung cancer evaluation and diagnosis. Signs and symptoms of lung cancer, which may not develop until later stages, may include:

  • Chest pain
  • Chronic cough that worsens with time
  • Difficulty breathing
  • Bloody cough, or sputum tinged with blood

Tests doctors use to diagnose lung cancer include:

  • Biopsy of suspected tumor tissue in the chest, lung or airway, which may require major surgery or less invasive procedures, such as bronchoscopy or mediastinoscopy
  • Analysis of sputum from a cough

Doctors recommend periodic lung cancer screening for people at risk for lung cancer who meet all these conditions:

  • Smoked a pack of cigarettes a day for at least 30 years or two packs a day for 15 years or more
  • Currently smoking or has quit in the last 15 years
  • 55 to 80 years old
  • In good enough health to withstand lung cancer treatment

The most recent recommendation, from March 2021, is lung cancer screening for ages 50 to 80 with a 20 pack-year history.

How is lung cancer treated?

The goal of lung cancer treatment is to permanently cure the cancer or to bring about a complete remission of the disease. Remission means that there is no longer any sign of the disease in the body, although it may recur or relapse later.

Lung cancer treatment plans are multifaceted individualized to the type and stage of lung cancer; your age, medical history, and coexisting diseases or conditions; and other factors. The most common type of lung cancer is non-small cell lung cancer; the second-most common type is small cell lung cancer; lung carcinoid tumor is least common form of lung cancer.

Lung cancer treatment may include an individualized combination of:

  • Chemotherapy in early- or late-stage lung cancer. In end-stage lung cancer, chemotherapy may be used only to help shrink the tumor to relieve symptoms.
  • Dietary counseling to help people with cancer maintain their strength and nutritional status
  • Immunotherapy to improve the body’s own ability to fight off cancer cells
  • Pain medications
  • Participation in a clinical trial to test promising new therapies and treatments for lung cancer
  • Physical therapy to help strengthen the body, increase alertness, reduce fatigue, and improve functional ability during and after cancer treatment
  • Quitting smoking to help slow or stop the growth of a lung cancer tumor
  • Supplemental oxygen
  • Surgery to remove the cancerous tumor and possibly all or part of a lung, which is generally most effective during the earliest stage of lung cancer
  • Targeted therapy to knock out factors that help cancer cells grow and multiply. Some targeted therapies are indicated for specific subtypes of lung cancer as well as for the presence of specific tumor gene mutations.

Complementary treatments

Some complementary treatments may help some people to better deal with lung cancer and treatment side effects. These treatments, sometimes referred to as alternative therapies, are used in conjunction with traditional medical treatments.

Complementary treatments are not meant to substitute for traditional medical care. Be sure to notify your doctor if you are consuming nutritional supplements or homeopathic (nonprescription) remedies as they may interact with the prescribed medical therapy.

Complementary treatments may include:

  • Massage therapy
  • Nutritional dietary supplements, herbal remedies, tea beverages, and similar products
  • Yoga

Hospice care

In cases in which lung cancer has progressed to an advanced stage and is not responding to treatment, the goal of treatment shifts away from curing the disease and focuses more on the person’s overall quality of life.

The goal of hospice care is to help people in the last phases of an incurable disease live as fully and comfortably as possible. Hospice care involves medically controlling pain and other symptoms while providing psychological and spiritual support as well as services to support the patient’s family.

What are the potential complications of lung cancer?

Complications of lung cancer are life threatening. Complications are caused by an abnormally rapid growth of old or damaged cells. These cells can metastasize, or spread through the bloodstream and lymphatic system to other areas of the body. Cancer cells can continue to multiply rapidly in other organs and develop new malignant tumors that interfere with normal organ function.

Over time, lung cancer can lead to serious complications including:

  • Adverse effects of anticancer treatment
  • Difficulty breathing
  • Frequent episodes of pneumonia and bronchitis
  • Metastasis of cancer to the other lung, brain, bones, adrenal glands, and liver
  • Pleural effusion, which is an accumulation of fluid in the space around the lungs that causes difficulty breathing and shortness of breath
  • Severe bleeding from the lungs
  • Severe pain

You can best treat lung cancer and lower your risk of complications, or delay the development of complications, by following the treatment plan you and your healthcare team design specifically for you.

How does lung cancer affect quality of life?

Lung cancer and its treatment significantly decrease quality of life, more so than with other cancers. While some lung cancer diagnoses occur at an early stage when a cure is possible, doctors discover most cases of lung cancer at a later stage. Treatment may successfully drive lung cancer into remission, but it may grow back—a lung cancer recurrence. About half a million people are living with or have survived lung cancer.

Lung cancer patients are impacted by:

  • Progression of cancer and symptoms
  • Recovery from and side effects of lung cancer surgery, such as reduced lung function
  • Fear of cancer recurrence or dying from lung cancer
  • Financial burden and planning for end of life

Patients who are older than 65, smoke, have a low income, or are female report a lower quality of life than patients who are younger than 65, do not smoke, are employed, or are male, according to a review on quality of life of patients with lung cancer.

What is the survival rate and prognosis for lung cancer?

Prognosis of lung cancer depends on the type of lung cancer and the stage of advancement; your age, medical history, and coexisting conditions or diseases; and available treatments.

A common cancer statistic is 5-year relative survival, which means the percentage of people alive five years from diagnosis time relative to people who do not have lung cancer.

The 5-year relative survival rate for lung cancer is 18%, but an individual patient’s survival may be longer or shorter than five years. The 5-year survival rate starts at about 92% for stage I lung cancer and decreases to 10% or lower for metastatic lung cancer.

Lung cancer treatment has undergone a revolution the past 10 to 20 years. As with many other cancers, the ability to more effectively target lung cancer cells with highly engineered therapies is allowing many more people to survive for longer periods of time.

Lung cancer awareness

In the United States, an estimated 235,760 people will develop lung cancer in 2021. That’s up from a total of 221,121 new cases in 2017. Although the rate of lung cancer has been dropping over the years, new cases are increasing annually because the population continues to grow and age.

Among new lung cancer diagnoses, the numbers indicate:

  • Men are diagnosed at a greater rate than women, meaning they are more likely than women to develop lung cancer. A person’s lifetime risk of lung cancer is 1 in 15 for men and 1 in 17 for women.
  • Most people are older than 65 years, and the average age at diagnosis is 70 years.
  • White and Black Americans develop lung cancer at a similar rate, but black men outnumber white men and white women outnumber black women.
  • More White and Black Americans develop lung cancer than Hispanic, Asian/Pacific Islander, and American Indian people in the United States.

How many people die of lung cancer?

Following the trend with rates of new diagnoses, the rate of lung cancer deaths is falling. However, the projected annual number of deaths—131,880 people in 2021—remains steady because of population growth.

Lung cancer screening is another way to improve lung cancer survival rates.

November is Lung Cancer Awareness Month.

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Medical Reviewer: William C. Lloyd III, MD, FACS
Last Review Date: 2020 Aug 21
THIS TOOL DOES NOT PROVIDE MEDICAL ADVICE. It is intended for informational purposes only. It is not a substitute for professional medical advice, diagnosis or treatment. Never ignore professional medical advice in seeking treatment because of something you have read on the site. If you think you may have a medical emergency, immediately call your doctor or dial 911.
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