What Is Lung Cancer?

Normal cells divide in a regulated way to form new cells, and after performing their functions for a while, they die. Cancer cells do not always die. Instead, these abnormal cells change their makeup and begin to multiply in an uncontrolled way. The cells join together and form a tumor.

Lung cancer is the growth of abnormal cells in one or both lungs. As these unhealthy cells form tumors, they block the ability of the lungs to provide oxygen to the body via the bloodstream. Cancer cells may remain localized, or they may metastasize (spread) and invade other parts of the body.

Lung cancers take a variety of forms, including

  • Squamous cell carcinoma (also called epidermoid carcinoma), which begins in the tissues that line the lungs and is most common in smokers
  • Adenocarcinoma, which is a tumor that starts in the cells lining the glands
  • Bronchoalveolar carcinoma, which is a form of adenocarcinoma that affects more women and nonsmokers than other types of lung cancers
  • Mesothelioma, which is a rare cancer associated with exposure to asbestos and smoking

Resources for more information:

Symptoms of Lung Cancer

In the earliest stages, a patient may not experience symptoms. However, as the condition advances, a patient may notice

  • A new cough that does not go away
  • Changes in a chronic cough
  • Coughing up blood (even a small amount)
  • Shortness of breath
  • Wheezing
  • Hoarseness
  • Pain

Patients with concerns about any of the signs and symptoms listed above are urged to consult their physician immediately.

Causes of Lung Cancer

People who smoke have the greatest risk of cancer. The risk increases with the frequency and duration of an individual’s exposure to tobacco—whether through smoking or by secondhand contact. Tobacco smoke damages the cells that line the lungs. Cigarette smoke contains cancer-causing substances (carcinogens) that alter lung tissue. The damage worsens with repeated exposure. Over time, the injured cells become abnormal, multiply, and form tumors.

People who quit smoking—even those who have smoked for many years—can significantly reduce their chances of developing cancer of the lungs.

Other factors that increase lung cancer risk include:

  • Inhaling secondhand smoke
  • Exposure to radon gas
  • Breathing in asbestos and other chemicals
  • A family medical history
  • A history of certain other lung diseases
  • Excessive alcohol use
  • A combination of the above

Cancer of the lung can also afflict nonsmokers and people who have never had prolonged exposure to secondhand smoke.

Lung Cancer Screening

Early detection saves lives. Learn more on our Lung Cancer Screening and Lung Nodule Evaluation Program page.

Diagnostic Tests


Several treatment modalities are available to treat lung cancer. Type and sequence of these treatments depend on several factors, the most important one being the stage of the cancer, i.e., degree of the cancer spread.

Departments and Programs Who Treat This Condition


Thoracic Cancer

Our thoracic cancer team is skilled across specialties from surgery to radiology to pulmonologists and more. Our experts work together – and with you – to provide personalized, co…

Lung Cancer

At Boston Medical Center (BMC), the care of patients with lung cancer is a collaborative, multidisciplinary process. In a highly supportive and patient-focused environment, the Ca…