ABSTRACT
The Pigmented Lesion Assay (PLA) is a gene expression test that helps rule out melanoma and has the potential to reduce the need for surgical biopsies of atypical pigmented skin lesions. Utilizing a new technological platform for the non-invasive profiling of skin, the assay analyzes samples collected from adhesive patches for expression of two key genes (PRAME and LINC00518) known to be overexpressed in melanoma. The test result is binary (positive/negative) based on the detection of one or both genes. PLA positive cases are generally biopsied to establish the histopathologic diagosis, while PLA negative cases are considered for ongoing monitoring. The combination of visual inspection with histopathology, the current gold standard for melanoma diagnosis, has a relatively low negative predictive value (NPV) of approximately 83%, meaning that 17% of melanomas will be interpreted as benign lesions. In contrast, the PLA has a very high NPV (>99%). Further, with its high specificity (69-91%), use of the PLA can reduce the number of false positive samples subjected to histopathology review. By adding the PLA to the current care pathway, the number of surgical biopsies needed to find a melanoma (number needed to biopsy) is markedly reduced from 20-25 biopsies for dermatologists and 39 biopsies for physician assistants, to an average of 2.7. To date, unnecessary surgical procedures of benign lesions have been reduced by 88% based on a sample of more than 20,000 analyzed cases. This has resulted in fewer missed melanomas and significant cost savings to health care systems.
