Lung cancer is the most common type of cancer worldwide. It often doesn’t cause symptoms until it enlarges within the lung or metastasizes (spreads) to other areas of the body. Smoking is the leading risk factor, but it can affect non-smokers as well. In the United States, lung cancer is the leading cause of death from cancer.
Paraneoplastic syndromes may trigger diagnostic testing. Diagnosis is established through imaging studies, tissue biopsy, and, sometimes, liquid biopsy blood tests. There are several types of lung cancer, each defined by the type of lung cell from which they started.
Treatment includes surgery, radiation, chemotherapy, immunotherapy, and/or symptom management. The outcome of lung cancer is generally better when it is diagnosed at an earlier stage, but each type of lung cancer has its own anticipated prognosis as well.
Lung cancer can be treated, but it is rarely cured. Surgery can relieve symptoms and remove some or all detectable cancer if it is confined. Cancer might not recur after treatment, but it may return if the cancer could not be fully treated due to advanced stage or undetectable tumor cells.
Lung cancer often doesn’t produce signs until late stages. Signs include persistent cough, hoarse voice, shortness of breath, chest tightness, hemoptysis (coughing up blood), lung infections, unexplained weight loss, and fatigue. Signs of progressive disease or metastasis include neck swelling, blood clots, and/or bone pain. Paraneoplastic effects include high calcium and low sodium.
Lung cancer is typically caused by smoking or secondhand smoke. Inhaled toxins from industrial chemicals, air pollution, and radon are also associated with lung cancer. These agents damage healthy lung cells and transform them into cancer cells through harmful mutations. Lung cancer cells are dysfunctional, grow rapidly, can invade healthy tissue, and can spread at distance.
Approximately 8% of lung cancers are inherited or occur as a result of a genetic predisposition. Alterations in several genes, including EGFR, ROS-1, ALK, and BRAF, are often detected with genetic testing for lung cancer but, most of the time, these alterations are not inherited. Sometimes treatment can be targeted toward these alterations and several oral agents are now available.
Imaging tests, including chest computerized tomography (CT), magnetic resonance imaging (MRI), or positron emission tomography (PET) may be used. Chest X-rays generally can’t detect lung cancer at an early stage. A biopsy can identify the type of lung cancer. Staging relies on biopsy features, size of the tumor, the presence of involved lymph nodes, and presence (or not) of metastases.
The most common type of non-small cell lung carcinoma. Smoking is the main cause, but it’s the leading type of lung cancer among non-smokers. It starts at the periphery of the lungs and is often associated with cancer mutations. Usually, this cancer is treated with surgery, radiation, and oral targeted agents. In recent years, immunotherapy has become the main systemic treatment for advanced and metastatic adenocarcinoma.
Large cell lung cancer is an aggressive cancer that is often diagnosed at a late stage when it causes shortness of breath and fatigue. It generally grows at the periphery of the lungs and the biopsy sampled cells appear large when examined microscopically. Sometimes, when the cancer is localized, a section of the lung or the whole lung may be surgically removed. Other treatments include chemotherapy and radiation.
Malignant cancer has the potential to invade healthy tissue and/or metastasize, and it can be fatal. Typically, malignant cancer cells have abnormal functions and grow rapidly. The malignant cancer cells may travel through blood and lymphatic vessels, depositing in lymph nodes and distant organs, where they may cause damage. Benign tumors differ from malignant tumors in that they are self-limited.
NSCLC is the most common type of lung cancer and includes adenocarcinoma, squamous cell carcinoma, and large cell carcinoma, as well as adenosquamous carcinoma, sarcomatoid carcinoma, and non-small cell neuroendocrine tumors, which are less common subtypes. Symptoms, diagnosis, and treatment differ depending on which type of NSCLC is present.
SCLC is aggressive, comprising about 15% of lung cancer diagnoses. Sometimes it might start in the bronchi and cause a hoarse voice and hemoptysis. Chemotherapy, immunotherapy, and radiotherapy may reduce symptoms and prolong survival. Surgery is rarely used in treatment because it often presents at advanced stages. Most of the cases of small cell carcinoma are incurable.
SCC is usually caused by smoking and is usually detected at an earlier stage than other types of lung cancer. Squamous cell lung tumors usually occur in the central part of the lung or in one of the main airways. When it is located at the top of the lung, it might invade the chest wall, the vessels, and the nerves in the area, causing Pancoast syndrome. Treatment can include surgery, chemotherapy, radiation, and immunotherapy.
Explore interactive models that show how lung cancer can progress in the body, and the changes that each stage of the disease refer to.
American Lung Association. Lung cancer fact sheet. Updated May 27, 2020.
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