Non-small cell lung cancer is an umbrella term that describes several types of lung cancers. It usually grows more slowly than small cell lung cancer. There are several treatment options available. Early diagnosis will help a person improve their prognosis.

Non-small cell lung cancer (NSCLC) is the most common type of lung cancer.

The biggest risk factor for this type of cancer is smoking. However, it is also the most common type of lung cancer non-smokers develop.

Understanding non-small cell lung cancer can help a person make treatment decisions that fit their goals and lifestyle, ask their doctor the right questions, and better advocate for quality care.

This article will explain what non-small cell lung cancer is. It will list stages of the cancer and possible causes, then describe symptoms and treatment options for the cancer. Finally, it will explain the outlook for a person with a diagnosis of non-small cell lung cancer.

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The term non-small cell lung cancer describes a group of cancers that includes the following:

  • Adenocarcinoma: This type of NSCLC is common in smokers. It is also the most prevalent form of lung cancer in non-smokers. It begins in mucus-secreting cells in the lungs. Doctors can often diagnose it before it spreads. A subtype of adenocarcinoma labeled “in situ,” a localized type of cancer that spreads more slowly, often has a better prognosis.
  • Squamous cell carcinoma: This type of cancer begins in a flat type of cell called squamous cells which line the airway, including the lungs. Doctors often find them near the main airway in the lungs.
  • Large cell (undifferentiated) carcinoma: This fast-growing cancer can appear anywhere in the lungs. A subtype, called large cell neuroendocrine carcinoma, behaves similarly to small cell lung cancer.

It is possible for tumors that are neither small cell nor non-small cell to grow in the lungs.

Other types of cancer, such as pancreatic cancer, may also spread to the lungs.

Learn about lung cancer mutations here.

The main difference between NSCLC and small cell lung cancer is that small cell lung cancer usually starts in the bronchi, which are the passages of the airway into the lungs. NSCLC starts in different locations depending on the subtype a person has.

Small cell lung cancer grows and spreads more quickly. Doctors usually identify non-small cell lung cancer at a later stage, when it may have spread.

Learn more about the differences between small cell and non-small cell lung cancer here.

Doctors usually divide non-small cell lung cancer into five stages based on how far the cancer has spread:

0Also called in situ cancer, this means that cancer is only in the top cells of the lungs, and has not spread outside the lungs
IThis cancer remains in the lungs, but has spread deeper into the lining of the lungs. Doctors may assign the letter A or B based on how deeply the cancer has penetrated the lungs.
IIThis cancer has spread either to lymph nodes near the lungs or to other structures in the lungs. It has not spread to other organs. The letter A or B further denotes how far the cancer has spread.
IIIThis cancer has spread to the lymph nodes of the chest. The letters A, B, or C indicate how many lymph nodes it has penetrated and how far it has traveled.
IVStage IV cancer has metastasized. This means it has spread to other organs, such as the liver or pancreas.

Treatment aims to cure, or completely eliminate, lung cancer in people with stages I, II, or III.

The goal of treatment with stage IV is to prolong a person’s life.

Stage IV cancer cannot usually be cured.

Learn about how quickly lung cancer can spread here.

Lung cancer happens when cells divide out of control in the lungs, causing tumors or damaging healthy tissue.

Doctors do not fully understand what causes cancer, or why some people with risk factors develop it while others do not.


Doctors estimate that smoking causes 90% of lung cancers. The risk increases the more a person smokes.

A person who smokes a pack a day for 40 years, or an equivalent amount in a different period of time, is about 20 times more likely to develop lung cancer.

Other risk factors

Some other risk factors include:

  • a family history of lung cancer, which may indicate a genetic predisposition to cancer, especially when there are environmental exposures such as smoking
  • exposure to radon, asbestos, arsenic, and some other chemicals
  • frequent exposure to secondhand smoke
  • exposure to some pollutants, such as car exhaust
  • smoking while taking beta-carotene supplements

Learn about lung cancer in non-smokers here.

Some people with NSCLC have no symptoms, especially in the early stages of the disease.

For people who do have symptoms, the first one they might notice is an unexplained chronic cough.

Some other symptoms include:

Doctors may suspect lung cancer based on a person’s medical history or symptoms. In some cases, a doctor may recommend lung cancer screenings for a person with a long history of smoking.

A doctor may recommend a series of tests, usually beginning with a chest radiograph, which produces an image of the lungs. If a doctor sees a suspicious area, they may next recommend a computed tomography (CT) scan, which can better characterize the area in question. The doctor will then review the history and physical examination of the patient along with the CT scan image to determine the next best step in evaluating any possible malignancy.

If the patient is considered at high risk for cancer and has a suspicious area on a CT scan, the doctor may recommend a lung biopsy. Looking at the tissue under the microscope may help identify whether the person has cancer, whether the cancer is NSCLC, and which type. This decision of how and where to biopsy is usually determined after a patient’s case is presented to a lung tumor multidisciplinary board.

A doctor may also recommend other imaging scans, such as magnetic resonance imaging (MRI) or PET-CT scan to assess whether the cancer has spread to other areas of the body.

Lung cancer treatment depends on the stage of cancer a person has, whether the cancer is curable, and a person’s treatment goals.

For example, some people want to forego chemotherapy if they have terminal cancer because they wish to avoid chemotherapy side effects. Others want aggressive treatment at all stages.

Some treatment options include:

  • Surgery: A doctor may be able to remove the tumor, or may recommend removing a portion of the lung.
  • Chemotherapy: Chemotherapy targets cancer cells, but can also kill healthy cells. It is very effective at shrinking or eliminating certain types of NSCLC. It can also prevent cancer from returning after surgery.
  • Radiation: Radiation, like chemotherapy, targets cancer cells. It uses concentrated injury to kill cells. A person may need radiation after chemotherapy.
  • Targeted therapies: Doctors sometimes recommend a different type of treatment, called targeted therapy. This can kill a certain type of cancer cell. A person may use these along with or instead of chemotherapy.
  • Experimental therapies: If a person does not respond well to treatment or has a very aggressive cancer, a doctor may recommend participating in a clinical trial. These trials can discover new treatments, though the treatments do not always work.

Sometimes, a doctor might recommend immunotherapy to treat NSCLC.

Learn about immunotherapy and NSCLC here.

A person should see a doctor if they have any symptoms of lung cancer, including a cough that does not go away or breathing difficulties.

After a diagnosis

People with cancer should regularly meet with their doctors. Call a doctor if:

  • A person develops new or worsening symptoms.
  • A person develops intense chemotherapy side effects, or cannot keep down food or water.
  • A person in remission redevelops cancer symptoms.

Lung cancer can be aggressive, and often spreads before a doctor catches it. The prognosis varies from person to person, and many stages of lung cancer are eventually fatal.

In general, the 5-year survival rate for lung cancer is 55% for cases detected when the disease is still localized (within the lungs). However, only 15% of lung cancer cases are diagnosed at an early stage. For distant tumors (ones that have spread to other organs) the 5-year survival rate is only 5%.

Learn more about metastatic lung cancer here.

Receiving a diagnosis of NSCLC may be a stressful experience. There are several mental health resources that can help a person come to terms with their diagnosis and treatment plans.

Learn about mental health resources here.

Lung cancer is a scary diagnosis, but doctors are constantly evaluating treatment options and exploring new potential cures.

People with lung cancer should work with an oncologist they trust, ask lots of questions, and talk to their loved ones about end-of-life preferences.