Background: Head and neck squamous cell carcinoma (HNSCC) is the 6th most common cause of cancer mortality. The ability to detect HNSCC at an earlier stage could have significant impact on overall outcome. A previous case-control validation study demonstrated that a point-of-care (POC) lateral flow assay measuring CD44 and total protein (TP), with the use of a visual tool, was successful in supporting the diagnostic process for HNSCC. We sought to understand the performance impact of an updated tool in the test result image assessment process.
Methods: Test result images were obtained from the original validation study and de-identified. The images were provided to two independent operators with the updated Graphic Education Tool (GET) with instructions to evaluate each image for presence or absence of a CD44 band and to grade the Total Protein from 0-4. A positive POC test is a visible CD44 band or TP>/=2. Performance was compared with original test results using sensitivity (Se), specificity (Sp), and negative predictive value (NPV). Inter-operator agreement was also evaluated.
Results: 134 evaluable patients: 28% (n=38) with SCC, 33% Stage I/II, average age 60 years, 60% males, 97% white, 74% smokers; vs. controls: average age 43 years, 96% white, 72% female and 100% non-smokers. Using POC presence of a CD44 band or a TP >/=2, the assay achieved an average Se (82%), Sp (40%) and NPV (95%) with a prevalence of 10% vs. original validation results of Se 84%, Sp 30% and NPV 95%. Inter-operator agreement had a Kappa of >>0.4 and was moderately significant.
Conclusions: Use of an updated graphic education tool with a >/=TP2 cut-off demonstrated comparable performance to original validation results with an observed improvement in specificity. Good inter-operator agreement was also noted.