Comparative evaluation of genetic assays to identify oral pre-cancerous fields.

BACKGROUND Oral squamous cell carcinomas often develop in a pre-cancerous field, defined as mucosal epithelium with cancer-related genetic alterations, and which may appear as a clinically visible lesion. The test characteristics of three genetic assays that were developed to detect pre-cancerous fields were investigated and compared to histology. METHODS In total, 10 pre-cancerous fields that were not visible at clinical inspection and gave rise to malignant transformation based on an identical TP53 mutation in tumor and mucosal epithelium in the surgical margin, as well as 10 normal oral mucosa specimens were analyzed for numerical chromosomal changes with multiplex ligation-dependent probe amplification (MLPA), for loss of heterozygosity (LOH), with microsatellite PCR and for DNA index alterations with DNA image analysis. RESULTS No alterations were detected in normal tissue by either of the assays. Both MLPA and LOH assays detected all pre-cancerous fields. DNA cytometry identified aneuploidy in four of 10 pre-cancerous fields, while the corresponding tumors that developed in these fields were shown to be aneuploid. CONCLUSIONS Both the MLPA and LOH assay seem suitable for screening pre-cancerous fields in subjects at high risk for oral cancer even in the absence of clinically abnormal appearing oral mucosa. Measurements of DNA index might be valuable to determine the time to progression.