Abstract

Lung cancer remains one of the leading causes of cancer-related mortality worldwide. It is primarily associated with tobacco smoking, environmental pollution, occupational exposure, and genetic predisposition. The disease is broadly classified into non-small cell lung cancer (NSCLC) and small cell lung cancer (SCLC). Despite advances in diagnostic imaging, targeted therapy, immunotherapy, and surgical techniques, the prognosis remains poor due to late-stage diagnosis in many patients. This article reviews the epidemiology, pathophysiology, clinical presentation, diagnostic methods, therapeutic approaches, and preventive strategies related to lung cancer. Early detection through screening and smoking cessation programs are essential for reducing mortality and improving patient outcomes.

Keywords: Lung cancer, Non-small cell lung carcinoma, Small cell lung carcinoma, Smoking, Immunotherapy, Oncology

Introduction

Lung cancer is a malignant neoplasm arising from the epithelial cells of the respiratory tract. It is among the most frequently diagnosed cancers globally and accounts for a substantial proportion of cancer deaths. According to global cancer statistics, lung cancer contributes significantly to morbidity and mortality in both developed and developing nations.

The primary etiological factor is cigarette smoking, responsible for approximately 85–90% of cases. Additional risk factors include passive smoking, exposure to asbestos, radon gas, air pollution, and occupational carcinogens. Genetic mutations such as EGFR, KRAS, ALK, and ROS1 also play important roles in carcinogenesis.

Lung cancer is classified into two major histological categories:

1. Non-Small Cell Lung Cancer (NSCLC)

   • Adenocarcinoma

   • Squamous cell carcinoma

   • Large cell carcinoma

2. Small Cell Lung Cancer (SCLC)

   • Highly aggressive and rapidly metastasizing

Despite improvements in medical technology and cancer therapeutics, lung cancer continues to present diagnostic and therapeutic challenges due to delayed presentation and metastatic spread at diagnosis.

The purpose of this article is to review the current understanding of lung cancer, including its epidemiology, risk factors, diagnosis, management, and preventive measures.

Methods

A narrative review methodology was utilized for this article. Relevant literature was obtained from peer-reviewed journals, oncology textbooks, and international cancer databases published between 2015 and 2026. Databases searched included:

• PubMed

• Google Scholar

• Scopus

• World Health Organization (WHO) publications

• American Cancer Society reports

Search terms included:

• “lung cancer”

• “NSCLC”

• “SCLC”

• “lung cancer treatment”

• “lung cancer screening”

• “immunotherapy in lung cancer”

Articles focusing on epidemiology, pathology, clinical presentation, diagnostics, and treatment modalities were reviewed. Studies with strong clinical relevance and evidence-based findings were included.

Results

Epidemiology

Lung cancer is the second most commonly diagnosed cancer worldwide but remains the leading cause of cancer-related deaths. Incidence rates are higher in males, although rates among females are increasing due to changing smoking patterns.

Major Risk Factors

• Cigarette smoking

• Secondhand smoke exposure

• Air pollution

• Radon exposure

• Occupational hazards (asbestos, silica, arsenic)

• Genetic susceptibility

Pathophysiology

Carcinogenesis involves progressive genetic mutations leading to uncontrolled cellular proliferation. Chronic exposure to carcinogens causes DNA damage, mutation accumulation, and malignant transformation.

Common mutations include:

• EGFR mutations

• KRAS mutations

• ALK rearrangements

• TP53 mutations

Clinical Presentation

Symptoms vary according to tumor size and metastasis.

Common Symptoms

• Persistent cough

• Hemoptysis

• Chest pain

• Dyspnea

• Weight loss

• Fatigue

• Hoarseness

Signs of Metastasis

• Bone pain

• Neurological deficits

• Hepatomegaly

• Pleural effusion

Paraneoplastic syndromes are more common in SCLC and may include:

• SIADH

• Cushing syndrome

• Lambert-Eaton myasthenic syndrome

Diagnosis

Imaging Techniques

• Chest X-ray

• Computed Tomography (CT)

• Positron Emission Tomography (PET)

• Magnetic Resonance Imaging (MRI)

Histopathological Diagnosis

• Bronchoscopy with biopsy

• Fine needle aspiration cytology

• CT-guided biopsy

• Sputum cytology

Molecular Testing

Molecular profiling is essential for targeted therapy selection.

Biomarkers include:

• EGFR

• ALK

• ROS1

• PD-L1 expression

Staging

The TNM staging system is used for NSCLC:

• Tumor size (T)

• Lymph node involvement (N)

• Metastasis (M)

SCLC is commonly categorized into:

• Limited stage

• Extensive stage

Treatment

Surgery

Preferred for early-stage NSCLC:

• Lobectomy

• Pneumonectomy

• Segmentectomy

Chemotherapy

Common agents include:

• Cisplatin

• Carboplatin

• Paclitaxel

• Etoposide

Radiotherapy

Used in:

• Localized tumors

• Brain metastases

• Palliative care

Targeted Therapy

Used in mutation-positive tumors:

• Osimertinib (EGFR)

• Crizotinib (ALK)

• Alectinib

Immunotherapy

Immune checkpoint inhibitors have significantly improved survival:

• Pembrolizumab

• Nivolumab

• Atezolizumab

Prevention

Preventive strategies include:

• Smoking cessation

• Public awareness campaigns

• Reduction of occupational exposure

• Air pollution control

• Low-dose CT screening in high-risk populations

Discussion

Lung cancer continues to represent a major public health challenge due to its high incidence and mortality rates. Smoking remains the single most important modifiable risk factor. Therefore, tobacco control measures are critical in reducing disease burden.

Recent advancements in molecular diagnostics and personalized medicine have revolutionized lung cancer management. Targeted therapies and immunotherapies have demonstrated improved survival outcomes compared to conventional chemotherapy in selected patients.

Early detection is essential for better prognosis. Low-dose CT screening has shown effectiveness in reducing mortality among high-risk individuals, particularly chronic smokers. However, accessibility, cost, and healthcare disparities remain barriers in many regions.

Although treatment outcomes have improved, metastatic lung cancer still carries a poor prognosis. Future research should focus on biomarker discovery, resistance mechanisms to therapy, and development of novel therapeutic agents.

Multidisciplinary management involving pulmonologists, oncologists, radiologists, thoracic surgeons, and palliative care specialists is essential for optimal patient care.

Conclusion

Lung cancer remains one of the deadliest malignancies worldwide. Tobacco smoking is the primary causative factor, although environmental and genetic influences also contribute significantly. Advances in imaging, molecular diagnostics, targeted therapies, and immunotherapy have improved diagnostic accuracy and treatment outcomes.

Early diagnosis through screening programs and aggressive smoking cessation efforts are crucial for reducing mortality. Continued research and global public health initiatives are necessary to improve survival rates and quality of life for patients with lung cancer.

References

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