Medically reviewed by C. Fookes, BPharm. Last updated on Apr 30, 2019.
Lung cancer is a cancerous lung disease that is primarily caused by smoking. It is the second most common cancer among both men and women in the U.S. and is the leading cause of cancer death in both sexes. Most people are diagnosed with lung cancer at a late stage because it often has no obvious symptoms until the disease is quite advanced.
Treatment for lung cancer may involve chemotherapy, radiation therapy, surgery or targeted drug therapies. Unfortunately, survival rates are low.
What is Lung Cancer?
Lung cancer is an abnormal growth of cells in the lining of the lungs. A clump of these cells together is called a tumor. Tumors of a certain size can be seen during an x-ray or another type of scan and may start to cause symptoms.
There are two main types of lung cancer – Small Cell Lung Cancer (SCLC) and Non-Small Cell Lung Cancer (NSCLC). SCLC and NSCLC differ in terms of their appearance under a microscope, how they grow and spread to other parts of the body and how they are treated.
NSCLC is the most common type of lung cancer, with approximately 85% of all lung cancers being NSCLC. There are three main types of NSCLC named for the type of cells in which the cancer develops: squamous cell carcinoma (also called epidermoid carcinoma), adenocarcinoma and large cell carcinoma. NSCLC generally grows and spreads more slowly than small cell lung cancer.
SCLCS, sometimes called oat cell cancer, is less common than non-small cell lung cancer. This type of lung cancer grows more quickly and is more likely to spread to other organs in the body.
What Causes Lung Cancer?
Approximately 90% of all lung cancers are associated with tobacco use. Cigarette smoking carries the highest risk and passive smoking (the inhalation of tobacco smoke by non-smokers who live or work with smokers, also called environmental tobacco smoke), is also an established risk factor. The risk of a cigarette smoker developing lung cancer is dependent on the number of cigarettes smoked each day, the age at which smoking began and how long the person has smoked. Stopping smoking greatly reduces the risk of developing lung cancer. However, not all smokers or ex-smokers develop lung cancer, suggesting that genetic susceptibility (the tendency to inherit certain conditions) also plays a role.
Other causes of lung cancer include air pollution (from vehicles, industry, and power generation) and inhalation of asbestos fibers (usually in the workplace).
Radon is an invisible, odorless, and tasteless radioactive gas that occurs naturally in soil and rocks. Exposure to radon (in mines or even houses) can cause damage to the lungs that may lead to lung cancer.
People with certain lung diseases are also at increased risk of developing lung cancer, for example, lung cancer tends to develop in areas of the lung that are scarred from tuberculosis (TB). A person who has had lung cancer once is more likely to develop a second lung cancer compared with a person who has never had lung cancer. Quitting smoking after lung cancer is diagnosed may prevent the development of a second lung cancer.
The best way to prevent lung cancer is to quit, or never start, smoking.
What is the survival rate of lung cancer?
Unfortunately for many people, lung cancer spreads (metastasizes) rapidly to other parts of the body very early after it forms.
This means that survival rates after diagnosis are quite low, with around 17% (or 17 out of every 100) people diagnosed with lung cancer still alive five years after their first diagnosis.
Symptoms of Lung Cancer
Symptoms of lung cancer vary among individuals, but may include:
- A cough that doesn't go away and gets worse over time
- Constant chest pain
- Coughing up blood
- Shortness of breath, wheezing, or hoarseness
- Repeated problems with pneumonia or bronchitis
- Swelling of the neck and face
- Loss of appetite or weight loss
These symptoms are common to several other conditions so having one or several of these symptoms does not mean you have lung cancer. See your doctor for a full investigation if you have any concerns.
How is Lung Cancer diagnosed?
A doctor may suspect lung cancer based on your symptoms and your medical history, family history, or history of smoking.
To confirm the diagnosis, a physical examination in addition to a chest x-ray and other tests, such as sputum cytology (the examination of cells under a microscope obtained by getting a person to cough deeply) are usually conducted.
A biopsy (the removal of a small sample of tissue for examination under a microscope by a pathologist) is used to confirm the presence of lung cancer. This may be done during one of several different procedures, such as:
• A bronchoscopy, where a thin, lighted tube is put into the mouth or nose and down through the windpipe to look into the breathing passages
• Needle aspiration, where a needle is inserted through the chest into the tumor to remove tissue samples
• Thoracentesis, where a needle is used to take a sample of the fluid that surrounds the lungs to check for cancer cells
• A thoracotomy, which is a major operation where the chest is opened.
How is Lung Cancer Staged?
Once a doctor has diagnosed your condition as cancer, then staging is done to determine the stage (or extent) of the disease. This finds out whether the cancer has spread, and if so, to which parts of the body. It is common for lung cancer to spread to the brain, bones, or liver. Staging may involve further testing and the taking of a series of detailed images using either a CAT scan or an MRI.
Radionuclide scanning can indicate the extent of spread of the cancer. A patient swallows or receives an injection of a mildly radioactive substance then a machine (or scanner) measures and records the level of radioactivity in certain organs to reveal abnormal areas. Bone scans are a type of radionuclide scan that can show whether cancer has spread to the bones. Lighted scopes may also be used to determine if the cancer has spread to the lymph nodes, in a procedure called mediastinoscopy.
The two types of lung cancer, NSCLC and SCLC, are staged differently.
Stage I: cancer confined to the lung
Stage II: cancer confined to the chest
Stage III: cancer confined to the chest but tumors are larger and more aggressive tumors than Stage II
Stage VI: cancer that has spread to other parts of the body.
Limited-stage: Cancer confined to the area of the chest
Extensive-stage: Cancer that has spread to other parts of the body.
Methods of Treatment of Lung Cancer and Side Effects
Treatment depends on a number of factors, including the type of lung cancer, the size, location, and extent of the tumor, and the general health of the patient. Many different treatments and combinations of treatments may be used to control lung cancer, and/or to improve quality of life by reducing symptoms.
Surgery may be used to remove the cancer, or a large part of the cancer. When only a small part of the lung is removed it is called a segmental or wedge resection. When the entire lobe of the lung is removed, the procedure is called a lobectomy. The removal of an entire lung is called pneumonectomyis. The type of surgery performed depends on the location of the tumor.
Lung cancer surgery is a major operation that is not without risk. After an operation, air and fluid tend to collect in the chest. Patients often need help turning over, coughing, and breathing deeply. Pain or weakness in the chest and the arm and shortness of breath are common side effects of lung cancer surgery. Patients may need several weeks or months to regain their energy and strength.
Chemotherapy is the use of anticancer drugs to kill cancer cells throughout the body. How chemotherapy is used in lung cancer is dependent on the type of lung cancer present (NSCLC or SCLC) and the stage of the disease.
Chemotherapy after surgery, known as adjuvant chemotherapy, has been shown to be beneficial for people with stage II or IIIA NSCLC that can be surgically removed.
For people with lung cancer that cannot be removed surgically, chemotherapy may be used in combination with definitive (high-dose) radiation treatments.
Chemotherapy is the main treatment in people with stage IV lung cancer. Radiation may help relieve some symptoms.
Most treatment for NSCLC usually consists of a combination of two chemotherapy drugs. Examples of chemotherapy drugs used to treat NSCLC include:
- Docetaxel (Docefrez, Taxotere)
- Etoposide (VePesid)
- Gemcitabine (Gemzar)
- Irinotecan (Camptosar)
- Paclitaxel (Taxol)
- Paclitaxel protein-bound (nab-paclitaxel, Abraxane)
- Pemetrexed (Alimta)
- Vinorelbine (Navelbine).
Single-drug treatment may be given for people who might not tolerate combination chemotherapy well. Studies have shown little benefit in adding a third chemo drug and an increased risk of side effects. Sometimes more chemotherapy may be needed after the first course has been given because the cancer has come back. Research is currently investigating the concept of maintenance chemotherapy, where one drug is continued for a longer period of time.
Side effects depend largely on the specific drugs and the dose (amount of drug given). Common side effects of chemotherapy include nausea and vomiting, hair loss, mouth sores, and fatigue.
The combinations of chemotherapy drugs most commonly used to treat SCLC are:
- Cisplatin and etoposide
- Carboplatin and etoposide
- Cisplatin and irinotecan
- Carboplatin and irinotecan
Targeted treatments work by targeting a specific cancer's genes, proteins, or other significant factor that contributes to its growth and survival. Some target a cancer's blood supply.
There are many different targeted treatments available. Examples of those used to treat NSCLC include:
- Angiogenesis inhibitors, for example, bevacizumab (Avastin), ramucirumab (Cyramza)
- Epidermal growth factor receptor inhibitors, for example, afatinib (Gilotrif), dacomitinib (Vizimpro), erlotinib (Tarceva), gefitinib (Iressa), necitumumab (Portrazza), osimertinib (Tagrisso)
- ALK protein targeted drugs, for example, alectinib (Alecensa), brigatinib (Alunbrig), ceritinib (Zykadia), crizotinib (Xalkori), lorlatinib (Lorbrena)
- BRAF protein targeted drugs, for example, dabrafenib (Tafinlar) and trametinib (Mekinist).
Targeted treatments for SCLC includes immune checkpoint inhibitors, such as nivolumab (Opdivo) or atezolizumab (Tecentriq). These drugs target proteins used by the cancer to switch off our immune system, helping to restore our immune response.
Radiation therapy (radiotherapy)
Radiation therapy involves the use of high-energy rays to kill cancer cells. It is directed to a limited area and affects the cancer cells only in that area, and may be used before surgery to shrink a tumor, or after surgery to destroy any cancer cells that remain in the treated area.
Side effects of radiation therapy depend mainly on the part of the body that is treated and the treatment dose. Common side effects of radiation therapy are a dry, sore throat; difficulty swallowing; fatigue; skin changes at the site of treatment; and loss of appetite.
Photodynamic therapy (PDT)
PDT is a type of laser therapy. It involves the use of a special chemical that is injected into the bloodstream and absorbed by cells all over the body. The chemical rapidly leaves normal cells but remains in cancer cells for a longer time. A laser light aimed at the cancer activates the chemical, which then kills the cancer cells that have absorbed it.
Photodynamic therapy may be used to reduce symptoms of lung cancer (to control bleeding or to relieve breathing problems due to blocked airways) when the cancer cannot be removed through surgery. Photodynamic therapy may also be used to treat very small tumors in patients for whom the usual treatments for lung cancer are not appropriate.
PDT makes the skin and eyes sensitive to light for 6 weeks or more after treatment. Patients are advised to avoid direct sunlight and bright indoor light for at least 6 weeks. If patients must go outdoors, they need to wear protective clothing, including sunglasses. Other temporary side effects of PDT may include coughing, trouble swallowing, and painful breathing or shortness of breath. Patients should talk with their doctor about what to do if the skin becomes blistered, red, or swollen.
Treating Small Cell Lung Cancer
Small cell lung cancer spreads quickly. In many cases, cancer cells have already spread to other parts of the body when the disease is diagnosed. In order to reach cancer cells throughout the body, doctors almost always use chemotherapy. Treatment may also include radiation therapy aimed at the tumor in the lung or tumors in other parts of the body. Surgery is part of the treatment plan for a small number of patients with small cell lung cancer.
Drugs used in the Treatment of Small Cell Lung Cancer
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