MOLECULAR TESTING OF MINIMALLY INVASIVE CYTOLOGY SPECIMENS IN PRECISION ONCOLOGY: ANALYTICAL CHALLENGES AND CLINICAL IMPLICATIONS: A SCOPING REVIEW

Abstract

Background: The increasing use of molecular testing in oncology has amplified reliance on diagnostic material obtained through minimally invasive procedures. In numerous clinical scenarios, cytological specimens represent the only available substrate for molecular and genomic analysis. Despite their growing clinical relevance, published studies addressing molecular testing in minimally invasive cytology remain methodologically diverse and analytically heterogeneous, complicating interpretation and comparison.
Objective: This scoping review sought to systematically identify molecular testing methodologies applied to minimally invasive cytology specimens, describe patterns of specimen utilization, classify reported clinical applications, evaluate laboratory and technical factors affecting analytical feasibility and reliability, and highlight recurrent methodological limitations and knowledge gaps within the literature.
Methods: The review followed the Arksey and O’Malley scoping review framework and was reported according to PRISMA-ScR guidance. A comprehensive search of major biomedical databases was conducted to identify studies describing molecular or genomic analyses performed on minimally invasive cytological specimens. Following duplicate removal, records underwent structured title, abstract, and full-text screening using predefined eligibility criteria. Relevant study characteristics and methodological data were extracted using a standardized charting approach.
Results: Two hundred studies met eligibility criteria and were included. The literature demonstrated substantial variability in molecular platforms,specimen preparation techniques, and clinical contexts. Next-generation sequencing and PCR-based assays were most commonly reported, with many studies employing multiple analytical approaches. Fine-needle aspiration cytology and cell block preparations predominated. Analytical feasibility was consistently influenced by specimen adequacy, cellularity, nucleic acid yield, and pre-analytical variability. Frequent methodological limitations included retrospective designs and inconsistent reporting practices.
Conclusion: The evidence reflects expanding integration of minimally invasive cytology into molecular diagnostic workflows across oncologic applications. However, heterogeneity in study design, laboratory practices, and reporting standards limits comparability and definitive assessment of analytical performance. Standardization efforts and prospective validation studies are needed to strengthen the evidence base.