What Is Lung Cancer?

Lung cancer is a malignant disease characterized by the uncontrolled growth of abnormal cells originating in the lung parenchyma, bronchial epithelium, or pleura, and it is the leading cause of cancer-related mortality worldwide. It is broadly classified into two major categories, non-small cell lung cancer (NSCLC) and small cell lung cancer (SCLC), which differ substantially in their cellular origin, growth rate, metastatic behavior, and treatment approach. The detection, characterization, and treatment of lung cancer involve extensive use of imaging technology, computational analysis, and medical devices, making it a significant area of research in biomedical engineering and IEEE-related disciplines.

NSCLC accounts for approximately 80 to 85 percent of all lung cancer diagnoses. Its principal subtypes are adenocarcinoma, which originates in mucus-secreting epithelial cells and is now the most common NSCLC subtype in many populations; squamous cell carcinoma, arising from the flat cells lining the bronchi; and large cell carcinoma. SCLC accounts for roughly 15 percent of cases and is distinguished by rapid doubling times, early metastasis, and a high initial sensitivity to chemotherapy that is typically not sustained.

Staging and Diagnosis

Lung cancer staging uses the TNM system, in which T describes tumor size and extent, N describes regional lymph node involvement, and M describes distant metastasis. Accurate staging requires integration of multiple imaging modalities: contrast-enhanced CT of the chest and abdomen provides structural detail of the primary tumor and lymph nodes, PET/CT using fluorodeoxyglucose (FDG) identifies metabolically active metastases, and brain MRI screens for central nervous system involvement. Tissue diagnosis is confirmed through bronchoscopy, CT-guided biopsy, or surgical resection of the tumor. The National Cancer Institute's treatment summary for non-small cell lung cancer provides a regularly updated clinical reference on staging criteria and evidence-based treatment options.

Imaging and Computational Detection

Computed tomography screening of high-risk populations has substantially improved early detection rates; the National Lung Screening Trial in the United States demonstrated a 20 percent reduction in lung cancer mortality from annual low-dose CT screening of current and former heavy smokers. Radiomics and machine learning approaches extract quantitative features from CT images, including nodule density, shape, texture, and growth rate, to distinguish malignant from benign lesions and to differentiate histological subtypes non-invasively. Research published in PMC examines CT radiomic methods for differentiating small cell from non-small cell lung cancer, illustrating how image-derived features can inform clinical decisions before biopsy. Artificial intelligence systems trained on large CT datasets have demonstrated detection sensitivity and specificity approaching that of radiologists in controlled studies.

Treatment Modalities

Treatment depends on histological subtype, molecular profile, and stage. Surgical resection is the standard of care for early-stage NSCLC. Radiation therapy, delivered as stereotactic body radiotherapy (SBRT) for small peripheral tumors or as conventionally fractionated external beam therapy, is used for patients who are not surgical candidates. Chemotherapy with platinum-doublet regimens is standard for advanced SCLC and for NSCLC lacking targetable driver mutations. Targeted therapies directed at driver mutations such as EGFR, ALK, and ROS1 rearrangements have substantially improved outcomes in the subset of NSCLC patients whose tumors harbor these alterations. Immune checkpoint inhibitors targeting PD-1 and PD-L1 pathways have become standard treatment for a broad range of NSCLC patients. The American Cancer Society overview of lung cancer types provides patient-accessible background on the biological basis of these distinctions. A NCBI Bookshelf entry on small cell lung cancer details the clinical behavior and treatment approach specific to SCLC.

Applications

Research and technology related to lung cancer has applications in a wide range of engineering and clinical domains, including:

• Low-dose CT screening programs for high-risk population surveillance
• AI-assisted nodule detection and risk stratification in radiology
• Computer-aided diagnosis systems for radiologists
• Radiation treatment planning and delivery systems for lung tumors
• Liquid biopsy devices for circulating tumor DNA detection