FocalPoint slide classification algorithms show robust performance in classification of high-grade lesions on SurePath liquid-based cervical cytology slides.
The FocalPoint Primary Screening System (FPPS) operates by assigning scores to each slide relative to the probability that an abnormality is present. This information ranks each slide within five "quintiles" (1 = highest risk, 5 = lowest risk) of the "review" population, allowing examining cytologists to understand the risk inherent in each slide. Such information helps to make the primary and quality control rescreening processes most efficient. This study examines the efficiency of AutoPap scoring and, thus, stratification of high-grade cases within a clinical trial setting. A total of 1,275 SurePath (TriPath, Burlington, NC) slides were screened on the FPPS. There were 124 high-grade cases in the set (32 HSIL, 5 AIS, and 87 cancers) as determined by cytologic truth adjudication. The efficiency of FPPS ranking was determined by analysis of the numbers of high-grade cases ranked into quintiles 1 (top 20%) and 1+2 (top 40%). FPPS places cases scored as "unsatisfactory" (HSIL, 3; Cancer, 18) into quintile 5 to ensure a manual review. These cases were excluded from the analysis. Overall, 58% of high-grade slides were classified as Q1 and 83% were classified as Q1+Q2. For HSIL, 66% were classified as Q1 and 90% as Q1+Q2. For Cancer, 59% were classified as Q1 and 84% as Q1+Q2. No high-grade slides were ranked in the lower "no review" population (slides that would receive no manual examination). The results confirm the robust performance of the FPPS classification algorithm. Far more high-grade slides are classified into the top two quintiles than would be expected by random chance alone (20% and 40%, respectively). These results validate the safety and effectiveness of this device on SurePath liquid-based slides.