Detection of cytogenetic changes and chromosomal aneuploidy with fluorescent in situ hybridization in cytological specimens of oral cancers in Fanconi anemia—Proof of concept

Objectives: Fanconi anemia (FA) is a rare inherited DNA instability disorder with a remarkably elevated risk of neoplasia compared with the general population, mainly leukemia and squamous cell carcinoma (SCC). Two thirds of the SCCs arise in the oral cavity and are typically preceded by visible lesions. These lesions can be classified with brush biopsy-based cytological methods regarding their risk of a malignant transformation. As a proof of concept, this study aims to investigate genetic changes and chromosomal aneuploidy using fluorescent in situ hybridization (FISH) on oral squamous cells derived from FA affected individuals. Material and Methods: Five FA oral SCC (OSCC) tumor cell lines, one FA OSCC cervical lymph node metastasis as well as tumor-negative and atypical smears from oral brush biopsies were analyzed with FISH probes covering 5p15.2, MYC, EGFR, TERC, 9q34.1, CCND1, 9p21 and centromeres of chromosomes 3, 6, 7, 9, 11, and 17. Results: OSCC specimens showed gains of all analyzed chromosomal regions. Chromosomal aneuploidy was observed in five of the six OSCC specimens in two multicolor FISH assays with panels of four probes each. Five out of six OSCC specimens displayed a relative deletion of 9p21. Applied on atypical brush biopsy-based smears, chromosomal aneuploidy was detected in malignant lesions but not in the smear derived from a severe parodontitis. Conclusions: As proof of concept, FISH was able to detect genetic changes and chromosomal aneuploidy discriminating oral cancer from noncancerous lesions in individuals with FA. This supports its application on oral brush biopsy-based cytology.