Non-Small Cell Lung Cancer — Common Lung Tumours

Non-small cell lung cancer is a broad umbrella term for several histologically distinct epithelial lung malignancies that share general clinical staging and management patterns. It is distinguished pathologically from small cell lung carcinoma, which features different cellular architecture, neuroendocrine markers, and rapid doubling times.

The three primary histological subtypes of NSCLC are adenocarcinoma, squamous cell carcinoma, and large cell carcinoma. Adenocarcinoma is the most common subtype, typically arising in peripheral lung tissues and frequently harbouring targetable oncogenic driver mutations. Squamous cell carcinoma usually originates centrally in the main bronchi, often associated with a significant history of tobacco exposure.

Over the past decade, NSCLC management has been transformed by precision medicine. Identifying whether your tumour is adenocarcinoma or squamous cell, along with testing for specific gene alterations, determines which therapies will be most effective. Many patients now receive targeted oral pills or immunotherapy instead of, or in addition to, conventional chemotherapy, often leading to improved outcomes and better quality of life.

Diagnosis relies on tissue biopsy via bronchoscopy, CT-guided needle biopsy, or surgical excision. Molecular biomarker testing is essential and checks for alterations in EGFR, ALK, ROS1, BRAF, RET, MET, and KRAS, as well as PD-L1 expression via immunohistochemistry. Staging involves chest CT, brain MRI, and whole-body PET-CT.

This term directly describes the most common form of lung cancer. Its major subtypes include adenocarcinoma (accounting for approximately 40% of cases), squamous cell carcinoma (around 25-30%), and large cell neuroendocrine or undifferentiated carcinomas. It can also involve surrounding structures such as the pleura, chest wall, or mediastinal lymph nodes.

Early-stage NSCLC is often managed with surgical resection, occasionally preceded or followed by chemotherapy, immunotherapy, or targeted therapy. Advanced stages are managed primarily with systemic therapies, including targeted tyrosine kinase inhibitors for oncogene-driven tumours, immune checkpoint inhibitors (such as pembrolizumab), chemotherapy, or specialised radiation therapy.