Lung Cancer: Incidence, Risks, and Diagnosis

Lung Cancer Impact: Eastern Europe and North America have the highest lung cancer incidence rates. Men are disproportionately affected, with rates 76% higher in men than in women in Eastern Europe and 69% higher in North America. However, incidence in women is increasing. The 5-year survival rate remains very low.

Risk Factors: Smoking accounts for a substantial portion of lung cancer deaths: 80% in men, 75% in women, and contributes to 17% of lung cancer cases in non-smokers. Smoking is also linked to 28% of all cancer deaths. Other risk factors include asbestos, radon exposure (mining or environmental), a diet low in vitamins A, C, E, and beta-carotene, as well as genetic and familial factors.

Lung Cancer Control: Effective control strategies involve comprehensive health policies, smoke-free environments, advertising limitations, school education programs, economic incentives (such as cigarette taxes), insurance discounts for non-smokers, media coverage and information dissemination, and addressing the social stigma associated with smoking.

Diagnostic Imaging:

• Chest X-ray: If a mass is visualized in the lung fissure on a chest X-ray, a differential diagnosis with a pseudotumor is necessary. Fluid in the fissure, as seen in heart failure, can mimic a pseudotumor.
• MRI: MRI is less sensitive than chest X-ray for lung cancer diagnosis and is primarily used for soft tissue evaluation.
• Bone Scan: Bone scans are utilized to assess bone involvement in non-small cell lung cancer and differentiate bone pain from other causes.

Incidence of Main Histological Types: 80% of lung cancers are non-small cell, categorized as follows:

• 40% Adenocarcinomas
• 30% Squamous cell carcinomas
• 18% Small cell carcinomas
• 15% Large cell carcinomas

Smoking habits and gender influence histological type. In men who smoke, squamous cell carcinoma is more common. Adenocarcinoma is more prevalent in non-smokers and female smokers.

Signs and Symptoms: Common symptoms include:

• Cough (75%)
• Weight loss (50%)
• Dyspnea (40%)
• Chest pain (40%)
• Hemoptysis (35%)

Less frequent symptoms include muscle weakness, anorexia, pneumonitis, fever, and anemia.

WHO Histological Classifications:

• Dysplasia
• Carcinoma in situ
• Malignant Epithelial Tumors: Squamous cell carcinoma, Spindle cell squamous carcinoma, Small cell carcinoma (oat-cell), Intermediate cell carcinoma, Combined oat-cell carcinoma
• Adenocarcinoma: Acinar, Papillary, Bronchoalveolar, Solid with mucus formation
• Large cell carcinoma: Giant cell, Clear cell, Adenosquamous carcinoma
• Carcinoid tumor
• Bronchial gland carcinoma: Adenoid cystic, Mucoepidermoid

TNM Staging:

T (Primary Tumor):

• Tx: Primary tumor cannot be assessed.
• T0: No evidence of primary tumor.
• T1: Tumor ≤ 3 cm, surrounded by lung or visceral pleura, no main bronchus invasion.
• T2: Tumor > 3 cm, invading visceral pleura, or causing atelectasis or pneumonitis extending to the hilum but not involving the entire lung; or invades main bronchus ≥ 2 cm from the carina.
• T3: Tumor of any size invading chest wall, diaphragm, mediastinal pleura, parietal pericardium, or main bronchus < 2 cm from carina; or causing atelectasis or obstructive pneumonitis of the entire lung.
• T4: Tumor of any size invading mediastinum, heart, great vessels, trachea, carina, esophagus, vertebral body; or associated with metastatic lung nodules in the same lobe; or producing malignant pleural effusion.

N (Regional Lymph Nodes):

• Nx: Regional lymph nodes cannot be assessed.
• N0: No regional lymph node metastasis.
• N1: Metastasis in ipsilateral peribronchial and/or hilar lymph nodes.
• N2: Metastasis in ipsilateral mediastinal and/or subcarinal lymph nodes.
• N3: Metastasis in contralateral mediastinal, contralateral hilar, ipsilateral or contralateral scalene, or ipsilateral or contralateral supraclavicular lymph nodes.

M (Distant Metastasis):

• Mx: Distant metastasis cannot be assessed.
• M0: No distant metastasis.
• M1: Distant metastasis present.