[Grading of lung cancer]

Area of Science:

• Oncology
• Pathology
• Cancer Research

Background:

• Established lung cancer grading systems with clear criteria and clinical relevance are lacking.
• The 2015 World Health Organization (WHO) classification does not provide a universally applicable grading for major lung carcinoma types.
• Recent classifications introduce subtypes for adenocarcinomas and histological criteria for squamous cell carcinomas, impacting prognosis.

Purpose of the Study:

• To review the current status of lung cancer grading systems.
• To highlight the absence of a standardized grading system for major lung cancer subtypes.
• To discuss proposed grading criteria for adenocarcinomas and squamous cell carcinomas.

Main Methods:

• Review of the 2015 World Health Organization (WHO) classification of lung tumors.
• Analysis of the 2011 International Association for the Study of Lung Cancer (IASLC)/American Thoracic Society (ATS)/European Respiratory Society (ERS) classification for adenocarcinomas.
• Examination of recent literature on histological grading criteria for squamous cell carcinoma.

Main Results:

• No common, clinically relevant grading system exists for lung cancer.
• Pulmonary adenocarcinomas are now classified into 5 subtypes with distinct prognoses based on architecture.
• Squamous cell carcinomas lack a unified grading system, though nesting and budding are proposed histological criteria.

Conclusions:

• The development of lung cancer grading systems is ongoing, with proposed refinements for adenocarcinomas and squamous cell carcinomas.
• Future advancements may include additional subtypes and cytological/nuclear criteria for improved lung cancer classification.
• Standardized grading is crucial for accurate prognosis and treatment planning in lung cancer management.