--- title: Lung Cancer url: "https://www.yyhmedical.com/en/guide/solid/disease-lung-cancer" type: MedicalWebPage inLanguage: en-US --- # Lung Cancer > Lung cancer is a malignancy that develops from cells in the lungs or airways. The two main types are non-small cell lung cancer (NSCLC) and small cell lung cancer (SCLC). Smoking is the most important risk factor, but lung cancer can also occur in people who have never smoked. ## Overview Lung cancer is broadly divided into non-small cell lung cancer (NSCLC) and small cell lung cancer (SCLC). NSCLC includes adenocarcinoma, squamous cell carcinoma, and several less common subtypes. Adenocarcinoma is one of the most common forms. Different subtypes can have distinct molecular features and treatment approaches. SCLC usually grows and spreads more rapidly and is strongly associated with smoking. Its treatment strategy differs substantially from that of NSCLC. Older descriptions such as “squamous cancer grows slowly” or “adenocarcinoma spreads early” are overly simplistic. The behavior of lung cancer depends not only on histology but also on stage, tumor biology, and molecular features. For NSCLC, biomarkers such as EGFR, ALK, ROS1, BRAF, MET, RET, NTRK, KRAS, HER2, and PD-L1 may affect treatment decisions. ## Causes and Risk Factors Lung cancer develops through a combination of genetic changes, environmental exposures, and other biological factors. Smoking is the most important known risk factor, including long-term tobacco use and exposure to secondhand smoke. In general, risk rises with greater cumulative exposure. Other risk factors may include: - Radon exposure - Occupational exposure to asbestos, arsenic, chromium, nickel, and other carcinogens - Air pollution - Previous radiation therapy to the chest - Certain chronic lung diseases - Family history and inherited susceptibility Lung cancer can also occur in people who have never smoked. Some lung adenocarcinomas in never-smokers are associated with specific driver mutations, so the absence of a smoking history does not rule out lung cancer. ## Signs and Symptoms Early lung cancer may cause no symptoms and may be found incidentally during chest imaging performed for screening or another reason. Possible symptoms include: - A persistent or worsening cough - Blood in sputum or coughing up blood - Chest pain - Shortness of breath, wheezing, or difficulty breathing - Hoarseness - Recurrent or persistent lung infections - Fatigue or weakness - Loss of appetite or unexplained weight loss When the tumor affects nearby structures, symptoms may include difficulty swallowing, hoarseness, or signs of compression of major blood vessels. Metastatic disease may cause symptoms depending on the affected organ. Brain metastases may cause headaches, seizures, nausea, or weakness; bone metastases may cause persistent pain or fractures. These symptoms do not necessarily mean lung cancer, but persistent or worsening symptoms should be medically evaluated. ## Diagnosis The diagnostic process usually has three major goals: identifying a suspicious lesion, obtaining tissue or cells to establish the diagnosis, and determining the stage and relevant biomarkers. Chest CT is an important imaging test for evaluating suspected lung lesions. PET/CT may be used to assess the extent of disease in selected patients. Brain MRI is often used in patients with more advanced disease to evaluate for brain metastases, depending on stage and symptoms. A definitive diagnosis usually requires tissue or cytology. Samples may be obtained through bronchoscopy, EBUS-guided biopsy, percutaneous needle biopsy, pleural fluid sampling, or surgery, depending on tumor location and clinical circumstances. Pathology determines whether the cancer is NSCLC or SCLC and identifies the specific histologic subtype. For patients with NSCLC who may need systemic treatment, comprehensive biomarker testing has become an essential part of treatment planning. Broad molecular profiling, often using next-generation sequencing, can identify actionable driver alterations. Blood-based circulating tumor DNA testing may also be used in selected situations, particularly when tissue is unavailable or insufficient. Important biomarkers may include EGFR, ALK, ROS1, BRAF, MET, RET, NTRK, KRAS, HER2, and PD-L1. ## Treatment Lung cancer treatment cannot be summarized simply as “surgery first.” Management depends first on whether the cancer is NSCLC or SCLC and then on stage, molecular biomarkers, PD-L1 expression, overall health, and sites of spread. **Non-Small Cell Lung Cancer** For early-stage resectable NSCLC, surgery remains an important curative treatment. Depending on tumor size and location, surgery may involve lobectomy, segmentectomy, or other procedures. Some patients also need treatment before or after surgery. Modern perioperative treatment may include chemotherapy, immunotherapy, or targeted therapy in selected patients with specific driver mutations. For unresectable locally advanced NSCLC, chemotherapy and radiation are often used together, followed by immunotherapy in selected patients. For advanced or metastatic NSCLC, determining whether the tumor has an actionable driver alteration is a key part of treatment planning. Targeted therapies are available for tumors with alterations involving EGFR, ALK, ROS1, RET, MET, BRAF, NTRK, KRAS G12C, HER2, and other biomarkers. When no actionable driver alteration is present, treatment may involve immunotherapy alone or in combination with chemotherapy, depending on PD-L1 expression, histology, and clinical factors. **Small Cell Lung Cancer** Treatment for SCLC is different. Limited-stage SCLC is generally treated with platinum-based chemotherapy combined with thoracic radiation. For extensive-stage SCLC, platinum plus etoposide combined with a PD-L1 inhibitor such as atezolizumab or durvalumab is an important first-line approach. Surgery is reserved for a very small group of patients with very early, localized disease. **R****adiation Therapy** Radiation can be used with curative intent for selected early-stage patients who cannot undergo surgery, as part of combined treatment for locally advanced disease, or to treat metastatic lesions such as those in the brain or bone. **Chemotherapy** Chemotherapy remains an important part of lung cancer treatment, but the regimen depends on cancer type, stage, and treatment setting. **Targeted Therapy** Targeted therapy works best when a tumor has a specific molecular alteration that can be matched with an appropriate drug. It does not affect cancer cells exclusively and can also cause significant side effects. **Immunotherapy** PD-1 and PD-L1 immune checkpoint inhibitors help restore the immune system's ability to recognize and attack cancer cells. Immunotherapy is now used across several stages of lung cancer, including perioperative treatment for selected NSCLC, consolidation treatment after chemoradiation for some locally advanced NSCLC, and first-line treatment for extensive-stage SCLC. ## Content attribution (YMYL) - Author: - Medically reviewed by: - Last reviewed: - First published: > --- Original (HTML):https://www.yyhmedical.com/en/guide/solid/disease-lung-cancer This is a clean Markdown mirror for large language models; the original page is authoritative.