Lung cancer is a type of cancer that begins in the lungs, the two spongy organs in the chest that take in oxygen during inhale and release carbon dioxide during exhale. Lung cancer is the second most common cancer for men and women, accounting for 14% of all new cancer cases in this country or 235,000 new patients annually. It is also the leading cause of cancer deaths in the United States, among both men and women, claiming more lives than colon, prostate, ovarian and breast cancers combined.
People who smoke have the greatest risk of lung cancer, though the disease can sometimes occur in people who have never smoked. The risk of lung cancer increases with the length of time and number of cigarettes smoked. Quitting smoking, even after years of use, can significantly reduce the chances of developing lung cancer. Smoking can cause lung cancer by damaging the cells that line the lungs. When cigarette smoke is inhaled, which is full of cancer-causing substances (carcinogens), changes in the lung tissue begin almost immediately. At first the body may be able to repair this damage, but with each repeated exposure, normal cells that line the lungs are increasingly damaged. Over time, the damage causes cells to act abnormally and eventually cancer may develop. Other risk factors include exposure to second-hand smoke, exposure to asbestos and other carcinogens and a family history of lung cancer.
Although signs and symptoms of lung cancer usually don’t appear until a later stage, they can include: a new cough that doesn’t go away; coughing up blood, even a small amount; shortness of breath; chest pain; hoarseness; unexplained weight loss; bone pain; trouble swallowing; swelling in neck veins; headaches. People with an increased risk of lung cancer may consider annual lung cancer screening using low-dose CT scans to try to catch the disease early.
Lung cancer is divided into two general types:
- Small Cell Lung Cancer (SCLC) occurs almost exclusively in heavy smokers and is less common than non-small cell lung cancer. SCLC accounts for 10-15% of all lung cancer.
- Non-Small Cell Lung Cancer (NSCLC) is an umbrella term for several types of lung cancers that behave in a similar way, including adenocarcinoma, squamous cell carcinoma and large cell carcinoma. NSCLC accounts for 80-85% of all lung cancer.
Adenocarcinoma: About 40% of lung cancers are adenocarcinomas. These cancers start in early versions of the cells that would normally secrete substances such as mucus. This type of lung cancer occurs mainly in current or former smokers, but it is also the most common type of lung cancer seen in non-smokers. It is more common in women than in men and it is more likely to occur in younger people than other types of lung cancer. Adenocarcinoma is usually found in the outer parts of the lung, and tends to grow slower than other types of lung cancer.
Squamous cell (epidermoid) carcinoma: About 25% to 30% of all lung cancers are squamous cell carcinomas. These cancers start in early versions of squamous cells, which are flat cells that line the inside of the airways in the lungs. They are often linked to a history of smoking and tend to be found in the central part of the lungs, near a main airway (bronchus).
Large cell (undifferentiated) carcinoma: This type accounts for about 10% to 15% of lung cancers. It can appear in any part of the lung. It tends to grow and spread quickly, which can make it harder to treat. A subtype of large cell carcinoma, known as large cell neuroendocrine carcinoma, is a fast-growing cancer that is very similar to small cell lung cancer.
To help diagnose lung cancer, imaging tests such as chest x-rays and CT scans may be used, along with sputum cytology (looking at sputum under a microscope). Procedures for tissue biopsies are commonly used in the diagnosis process as well and can include:
Bronchoscopy– examination of abnormal areas of the lungs using a lighted tube that is passed down the throat and into the lungs.
Mediastinoscopy– an incision is made at the base of the neck and surgical tools are inserted behind the breastbone to take tissue samples from lymph nodes.
Fine-Needle Aspiration– an ultrasound, CT scan or other imaging tests are used to guide a needle through the chest wall and into the lung tissue to collect suspicious cells.
Thoracoscopy– examination of the organs inside the chest using a lighted tube and lens that is inserted between two ribs through a small incision.
Thoracentesis– needle removal of fluid from between the lining of the chest and lungs
After a patient is diagnosed with lung cancer, further tests may be done to determine if the cancer has spread and to identify to what stage the disease has progressed. An MRI, CT scan, PET scan, bone scan and breathing test may be used to determine staging, along with ultrasounds and various surgical procedures such as lymph node removal and bone marrow aspiration and biopsy.
Staging for non-small cell lung cancer:
Occult (hidden)– Cancer cells are seen in a sample of sputum or other lung fluids, but the cancer isn’t found with other tests, so its location can’t be determined. The cancer is not thought to have spread to any other parts of the body.
Stage 0– The tumor is found only in the top layers of cells lining the air passages, but it has not invaded deeper into other lung tissues. The cancer has not spread to nearby lymph nodes or to distant parts of the body.
Stage IA– The tumor is in the lung only and is 3 centimeters or smaller.
Stage IB- The cancer is a minimally invasive and one or more of the following:
- The tumor is larger than 3 centimeters.
- Cancer has spread to the main bronchus of the lung and is at least 2 centimeters from the carina (where the trachea joins the bronchi).
- Cancer has spread to the innermost layer of the membrane that covers the lungs.
- The tumor partly blocks the bronchus or bronchioles and part of the lung has collapsed or developed pneumonitis (inflammation of the lung).
Stage IIA– The tumor is 3 centimeters or smaller and cancer has spread to nearby lymph nodes on the same side of the chest as the tumor.
Stage IIB- Cancer has spread to nearby lymph nodes on the same side of the chest as the tumor and the tumor has one or more of the characteristics listed above in Stage IB.
Cancer has not spread to lymph nodes and one or more of the following is true:
- The tumor may be any size, and cancer has spread to the chest wall, or the diaphragm, or the pleura between the lungs, or membranes surrounding the heart.
- Cancer has spread to the main bronchus of the lung and is no more than 2 centimeters from the carina, but has not spread to the trachea.
- Cancer blocks the bronchus or bronchioles, and the whole lung has collapsed or developed pneumonitis.
Stage IIIA– The tumor may be any size and has spread to lymph nodes on the same side of the chest as the tumor, and has one or both of the following:
- Cancer may have spread to the main bronchus, the chest wall, the diaphragm, the pleura around the lungs, or the membrane around the heart, but has not spread to the trachea.
- Part or all of the lung may have collapsed or developed pneumonitis.
Stage IIIB- The tumor may be any size and has spread to lymph nodes above the collarbone or in the opposite side of the chest from the tumor.
Cancer has spread to the heart, major blood vessels that lead to or from the heart, the chest wall, the diaphragm, the trachea, the esophagus, the sternum or backbone, more than one place in the same lobe of the lung, or the fluid of the pleural cavity surrounding the lung.
Stage IV– Cancer may have spread to lymph nodes and has spread to another lobe of the lungs or to other parts of the body, such as the brain, liver, adrenal glands, kidneys, or bone.
Staging for small cell lung cancer:
Limited-Stage Small Cell Lung Cancer: Cancer is found in one lung, the tissues between the lungs, and nearby lymph nodes only.
Extensive-Stage Small Cell Lung Cancer: Cancer has spread outside of the lung in which it began or to other parts of the body.
Once cancer has been diagnosed and the appropriate stage as been determined, the next step is to develop a treatment plan based on the tumor, the stage and the overall health of the patient.
Different types of doctors on may be a part of a patient’s treatment team, depending on the stage of the cancer and the treatment options. These doctors could include a thoracic surgeon (who treats diseases of the lungs and chest with surgery), a pulmonologist (who specializes in medical treatment of diseases of the lungs), as well as a medical oncologist and radiation oncologist.
For Non-Small Cell Lung Cancer (NSCLC), treatment options include can include any of the following:
Surgery– Surgery to remove the cancer (often along with other treatments) may be an option for early NSCLC. If surgery can be done, it provides the best chance for a cure. Lung cancer surgery is a complex operation that can have serious consequences, so it should be done by a surgeon who has a lot of experience operating on lung cancers. With any of these operations, nearby lymph nodes are also removed to look for possible spread of the cancer.
- Pneumonectomy: This surgery removes an entire lung. This might be needed if the tumor is close to the center of the chest.
- Lobectomy: The lungs are made up of 5 lobes (3 on the right and 2 on the left). In this surgery, the entire lobe containing the tumor(s) is removed. This is often the preferred type of operation for NSCLC if it can be done.
- Segmentectomy or wedge resection: In these surgeries, only part of a lobe is removed. This approach might be used, for example, if a person doesn’t have enough lung function to withstand removing the whole lobe.
- Sleeve resection: This operation may be used to treat some cancers in large airways in the lungs. If you think of the large airway with a tumor as similar to the sleeve of a shirt with a stain a couple of inches above the wrist, the sleeve resection would be like cutting across the sleeve above and below the stain and then sewing the cuff back onto the shortened sleeve. A surgeon may be able to do this operation instead of a pneumonectomy to preserve more lung function.
- Video-assisted thoracic surgery (VATS): Increasingly, doctors now treat early-stage lung cancers in the outer parts of the lung with VATS, which requires smaller incisions than a thoracotomy. During this operation, a thin, rigid tube with a tiny video camera on the end is placed through a small cut in the side of the chest to help the surgeon see inside the chest on a TV monitor. One or two other small cuts are created in the skin, and long instruments are passed through these cuts to do the same operation that would be done using an open approach (thoracotomy). One of the incisions is enlarged if a lobectomy or pneumonectomy is done to allow the specimen to be removed. Because only small incisions are needed, there is usually less pain after the surgery and a shorter hospital stay.
Radiofrequency Ablation (RFA)- This treatment might be an option for some people some small lung tumors that are near the outer edge of the lungs, especially if they can’t tolerate surgery. RFA uses high-energy radio waves to heat the tumor. A thin, needle-like probe is put through the skin and moved in until the tip is in the tumor. Placement of the probe is guided by CT scans. Once the tip is in place, an electric current is passed through the probe, which heats the tumor and destroys the cancer cells.
Radiation Therapy– There are 2 main types of radiation therapy: External Beam Radiation Therapy and Brachytherapy (internal radiation therapy).
- External beam radiation therapy (EBRT) focuses radiation from outside the body on the cancer. This is the type of radiation therapy most often used to treat NSCLC or its spread to other organs. In recent years, newer EBRT techniques have been shown to help doctors treat lung cancers more accurately while lowering the radiation exposure to nearby healthy tissues. These include:
- Three-dimensional conformal radiation therapy (3D-CRT): uses special computers to precisely map the tumor’s location. Radiation beams are then shaped and aimed at the tumor(s) from several directions, which makes it less likely to damage normal tissues.
- Intensity modulated radiation therapy (IMRT): is an advanced form of 3D therapy. It uses a computer-driven machine that moves around you as it delivers radiation. Along with shaping the beams and aiming them at the tumor from several angles, the intensity (strength) of the beams can be adjusted to limit the dose reaching nearby normal tissues. This technique is used most often if tumors are near important structures such as the spinal cord.
- Stereotactic body radiation therapy (SBRT): also known as stereotactic ablative radiotherapy (SABR), is sometimes used to treat very early-stage lung cancers when surgery isn’t an option due to a person’s health or in people who don’t want surgery. Instead of giving a small dose of radiation each day for several weeks, SBRT uses very focused beams of high-dose radiation given in fewer treatments. Several beams are aimed at the tumor from different angles.
- Stereotactic radiosurgery (SRS): is a type of stereotactic radiation therapy that is given in only one session. It can sometimes be used instead of or along with surgery for single tumors that have spread to the brain. In one version of this treatment, a machine called a Gamma Knife® focuses about 200 beams of radiation on the tumor from different angles over a few minutes to hours. In another version, a linear accelerator (a machine that creates radiation) that is controlled by a computer moves around the head to deliver radiation to the tumor from many different angles.
- Brachytherapy (internal radiation therapy) can be used to shrink tumors in the airway to relieve symptoms. For this type of treatment, the doctor places a small source of radioactive material (often in the form of small pellets) directly into the cancer or into the airway next to the cancer. This is usually done through a bronchoscope, but it may also be done during surgery. The radiation travels only a short distance from the source, limiting the effects on surrounding healthy tissues. The radiation source is usually removed after a short time. Less often, small radioactive “seeds” are left in place permanently, and the radiation gets weaker over several weeks.
Chemotherapy- anti-cancer drugs injected into a vein or taken by mouth. These drugs enter the bloodstream and go throughout the body, making this treatment useful for cancer anywhere in the body. Chemotherapy is typically used in combination before, after, or during other treatments such as surgery and radiation therapy. There are many options for chemotherapy drugs, so deciding which one to use in a patient’s treatment plan will depend on the tumor and the staging, along with other health factors.
Targeted Therapies and Immunotherapies– these newer therapies are becoming more commonly used either in combination with other treatments or by themselves. Targeted therapies are able to target specific tumor characteristics or changes, such as medicines that target tumor blood vessel growth (angiogenesis) or ones that target cells with Epidermal growth factor receptor (EGFR) changes. Immunotherapy is the use of medicines to stimulate a person’s own immune system to recognize and destroy cancer cells more effectively.
For Small Cell Lung Cancer (SCLC), treatment options typically include surgery, chemotherapy, radiation therapy, laser therapy and endoscopic stent placement (used to open an airway blocked by abnormal tissue).