Lung Cancer

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Understanding lung cancer.

Lung cancer is the leading cause of cancer death among men and women. Tobacco is the leading risk factor for lung cancer, but about 20% of people who receive a diagnosis have never smoked or used any other form of tobacco.

Many new therapies, including targeted drugs and immunotherapies, have been approved in recent years to treat lung cancer, improving outcomes for many who have the disease.


Lung cancer occurs when cells inside the lungs grow out of control.

The cancer can start in the bronchi, tubes that allow air to move from the trachea into the lungs; bronchioles, tiny tubes that carry air farther inside the lungs; or alveoli, air sacs within the lungs.

There are two types of lung cancer: non-small cell and small cell.

Non-small cell lung cancer, by far the most common type, is divided into three groups, or subtypes.

  • Adenocarcinoma starts in the cells that secrete substances such as mucus. Although it occurs mainly in people who have smoked, it’s also the most common kind of lung cancer in never smokers. It is found in the outer part of the lungs and most likely to be discovered before it has spread.
  • Squamous cell carcinoma occurs in the center of the lungs in cells that line the inside of the airway and is often linked with a history of smoking.
  • Large cell, or undifferentiated, lung cancer can appear anywhere in the lungs and tends to grow and spread aggressively.

Small cell lung cancer tends to grow and spread faster than non-small cell lung cancer. More treatments are available for non-small cell lung cancer than for small cell lung cancer.


Smoking is the leading risk factor for lung cancer. Others include secondhand smoke; exposure to radon, asbestos or workplace chemicals; radiation therapy to the lungs; air pollution; and a personal or family history of lung cancer.


Lung cancer often causes no symptoms until it has grown past the early stage. Symptoms can include a persistent, worsening cough that may bring up blood; chest pain, especially with deep breathing or laughing; hoarseness; loss of appetite; shortness of breath; fatigue; wheezing; and bronchitis or pneumonia.

Lung cancer that spreads to other parts of the body can cause bone pain, such as in the back or hips; nervous system changes such as headache, dizziness or seizures; yellowed skin or eyes; or swollen lymph nodes.


Most lung cancers are found due to symptoms, although some are detected through screening. Health insurers will cover periodic screening via low-dose CT scan for people with a history of heavy smoking. Screening can reveal lung cancers when they are still too small to cause symptoms and are more likely to be curable.

Doctors who suspect lung cancer can also use chest X-ray; MRI; positron emission tomography (PET) scan; or bone scan, which uses radioactive material to pinpoint abnormal areas. Only low-dose CT scans are recommended to screen for lung cancer.

If any of those tests points to lung cancer, pathologists in a lab can look at the cells to determine whether they are cancerous. The cells can be from mucus coughed up from the lungs, fluid removed from the area around the lungs, or a needle or surgical biopsy of lung tissue.

If cancer is present, any spread past the lungs can be revealed through additional tests: ultrasound of the lymph nodes; mediastinoscopy or mediastinotomy, which checks between the lungs; and thoracoscopy, which checks the spaces between the lungs and chest wall.

Patients with lung cancer should request that a pathologist conduct comprehensive biomarker, or genomic, testing of their tumor tissue, which can help determine which treatments are likely to be most effective. This kind of test looks for altered genes that drive cancer and can be treated with targeted therapies. There are approved targeted therapies for alterations in these genes: EGFR, ALK, ROS1, RET, NTRK, MET and BRAF. Testing may also look for gene alterations that do not have approved therapies but have drugs being tested in clinical trials. Comprehensive biomarker testing also includes looking at levels of a certain protein called PD-L1, which may influence whether a patient should receive immunotherapy.

Non-small cell lung cancer is divided into stages from 0, the least advanced, through 4, the most advanced. Small cell lung cancer is divided into two stages: limited and extensive.


Non-Small Cell Lung Cancer

For early-stage disease, surgically removing part of the lung may be the only treatment needed. Surgery may be followed by chemotherapy and/or radiation.

Treatment for stage 2 non-small cell lung cancer entails surgical removal of part or all of the affected lung and any cancerous lymph nodes followed by chemotherapy to kill any remaining cancer.

The mainstays of stage 3 treatment are chemotherapy and radiation given together, sometimes followed by surgery if the cancer can be removed, and then more chemotherapy and radiation. If the cancer has grown too much to be completely removed by surgery, chemotherapy and radiation alone may control or even cure it. These treatments can be followed by immunotherapy to help keep the disease stable.

Stage 4 non-small cell lung cancer has spread extensively and is difficult to cure. The goal of treatment is to prolong life and increase physical comfort. Therapies are selected based on the number of tumors and their location. The same treatments used in earlier stages, plus targeted therapies and immunotherapies, can be considered depending on the results of tests done on the tumor cells. Some of these newer biological therapies can extend lives.

Small Cell Lung Cancer

Chemotherapy and radiation therapy to the chest are typical treatments; sometimes surgery is performed first, but it is not possible in many cases.

Radiation therapy to the head may also be used to help prevent the cancer’s spread to the brain.

If the cancer is extensive, chemotherapy plus immunotherapy is usually the first treatment. This may be followed with radiation to the chest and brain.

Clinical trials of new treatments can be considered for either limited or extensive small cell lung cancers, which may shrink significantly with standard therapy but have a high likelihood of recurring.


Side effects of surgery can include pain, cough, fatigue and difficulty breathing. Chemotherapy can cause low blood counts that can lead to infection, nausea, diarrhea, hair loss, fatigue, mouth sores and numbness or tingling in the extremities. Those who get radiation might experience mild skin reactions, nausea, fatigue and sore throat.

Targeted drugs can cause high blood pressure, bleeding, headaches, mouth sores, diarrhea, skin problems, constipation, vision changes and dizziness. Immunotherapy can cause fatigue, nausea, cough, itching, joint pain, constipation and diarrhea. A palliative care specialist can help patients with lung cancer manage side effects at all stages.


Lung cancer stigma can impact patients’ experience seeking support. Symptoms from the disease or side effects that arise from treatment can impact quality of life, so patients should talk with their providers about the importance of emotional and physical support during this time.


The American Lung Association (, 800-586-4872) offers information about lung cancer, online support communities, initiatives to raise aware- ness and funding, and more. Visit to learn more. And don’t forget to visit CURE®’s resources guide at to learn about additional help that is available.

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Image of Dr. Minesh Mehta at ASCO 2024.