Summary of Lung Cancer: Overview, Diagnosis, and Treatment

## Introduction Lung cancer is a serious disease that arises from the malignant transformation of pulmonary epithelium or adjacent structures. The aim of this text is to provide an overview of the etiology, clinical manifestations, diagnosis, staging, and basic treatment options, along with practical examples and recommendations for clinical decision-making. ## Basic Classification ### Main Histological Types - **Small cell lung cancer (SCLC)** — ~25% of all lung cancers - **Non-small cell lung cancer (NSCLC)** — ~75%; includes: - squamous cell carcinoma - adenocarcinoma - large cell carcinoma - bronchoalveolar carcinoma > Definition: SCLC = a malignant tumor characterized by rapid growth and early dissemination, NSCLC = a heterogeneous group of tumors that typically grow more slowly and may be more amenable to surgical resection. ## Risk Factors - **Smoking** — accounts for >85% of cases; risk increases linearly with pack-years - **Adenocarcinoma** has the weakest, yet still present, association with smoking - **Asbestos**, **radon**, **exposure to toxic substances**, chronic obstructive pulmonary disease (COPD) as an independent risk factor Did you know that the combination of smoking and asbestos exposure synergistically increases the risk of developing lung cancer? ## Clinical Manifestations Most tumors are initially asymptomatic and are often discovered incidentally on X-rays. Symptoms typically arise due to local growth, airway obstruction, invasion, or paraneoplastic phenomena. ### Local Symptoms - Cough, bleeding from the respiratory tract (hemoptysis), dyspnea (shortness of breath), wheezing - Post-obstructive pneumonia (recurrent pneumonia) - Chest pain - Dysphagia (esophageal compression) ### Syndromes Due to Invasion of Adjacent Structures - SVC syndrome: superior vena cava obstruction → facial and neck swelling, chest vein dilation - Neural compression: nerve paresis - Hoarseness (recurrent laryngeal nerve paresis) - Horner's syndrome (sympathetic innervation) — ptosis, miosis, anhidrosis - Pulmonary apex / Pancoast tumor: shoulder pain, paresthesia, weakness in the upper extremity - Diaphragmatic paresis (phrenic nerve) ### General Symptoms (Constitutional) - Weight loss, anorexia, weakness — usually a sign of advanced disease ### Paraneoplastic Syndromes - SIADH (more common in SCLC) - Ectopic ACTH (SCLC) - Secretion of PTH-like hormone (more common in squamous cell carcinoma) - Hypertrophic osteoarthropathy (joint and long bone pain) — adenocarcinoma, squamous cell carcinoma - Eaton–Lambert syndrome (SCLC) — proximal muscle weakness - Clubbing (excessive curvature of the nail bed) Fun fact: The prognosis for SCLC is worse than for NSCLC; for limited disease, the 5-year survival rate is approximately 10–13%, while for extensive disease, it is only 1–2%. ## Solitary Pulmonary Nodule (SPN) - A simple, well-circumscribed nodule without associated mediastinal lymphadenopathy - The key clinical question: benign vs. malignant → guiding subsequent management (CT surveillance, PET, biopsy, resection) Factors favoring benignity vs. malignancy (table below): | Factor – Benign | Factor – Malignant | | --- | --- | | Age < 50 years | Age > 50 years | | Non-smoker | Smoker / Former smoker | | Size < 2 cm | Size > 3 cm | | No growth over 2 years | Persistent growth on serial imaging | | Round, regular shape | Irregular, lobulated, spiculated margin | | Central, dense calcification | Eccentric or stippled calcification | Practical approach to a nodule: 1. Low-probability → serial CT (surveillance) 2. Intermediate-probability and size ≥ 1 cm → PET/CT 3. High-probability → biopsy (transbronchial, transthoracic) or video-assisted thoracoscopic resection ## Diagnosis ### Imaging Methods - Chest X-ray (CXR) — often the first step; many tumors are found incidentally - If findings are stable after 2 years, highly likely to be benign - Contrast-enhanced Chest CT — method of choice for staging and detail