Systematic scoping review of external validation studies of AI pathology models for lung cancer diagnosis

Clinical adoption of digital pathology-based artificial intelligence models for diagnosing lung cancer has been limited, partly due to lack of robust external validation. This review provides an overview of such tools, their performance and external validation. We systematically searched for external validation studies in medical, engineering and grey literature databases from 1st January 2010 to 31st October 2024. 22 studies were included. Models performed various tasks, including classification of malignant versus non-malignant tissue, tumour growth pattern classification and subtyping of adeno- versus squamous cell carcinomas. Subtyping models were most common and performed highly, with average AUC values ranging from 0.746 to 0.999. Although most studies used restricted datasets, methodological issues relevant to the applicability of models in real-world settings included small and/or non-representative datasets, retrospective studies and case-control studies without further real-world validation. Ultimately, more rigorous external validation of models is warranted for increased clinical adoption.