Clinical Trials of the FocalPoint GS System Show Significant Improvements in Sensitivity for the Detection of Squamous Intraepithelial Lesions When Compared to Manual Screening
DC Wilbur, WS Black-Schaffer, RD Luff, TM Molina, KP Abraham, C Kemper, WD Tench. Massachusetts General Hospital, Boston, MA; Quest Diagnostics, Teterboro, NJ; Cyto Laboratories, San Antonio, TX; Quest Diagnostics, Schaumberg, IL; Boyce & Bynum Pathology, Columbia, MO; Palomar Medical Center, Escondido, CA
Background: Location-guided screening of cervical cytology specimens is a significant advance over routine manual screening. In order to determine if use of the FocalPoint GS System (BD/TriPath) is more effective that manual screening, a large clinical trial was performed.
Design: A 2-armed, masked, adjudicated trial, using SurePath slides (BD/TriPath) was run at 4 clinical sites. The control arm (CA) consisted of routine manual screening and quality control (QC) rescreening, and the experimental arm (EA) consisted of screening by the FocalPoint GS, cytotechnologist review of up to 11 fields of view (FOV), with signout as negative or escalation to full manual screening, QC rescreening, and pathologist review as appropriate. All positive, discordant, and a subsampling of negative slides were adjudicated to a reference diagnosis. The results obtained in the two arms were compared to the reference diagnoses and sensitivity, specificity, and negative predictive value (NPV) were calculated for ASC-US+, LSIL+ and HSIL+ groups.
Results: 12,313 slides were evaluated. The detection sensitivities for HSIL+ were 85.3% (EA) and 65.7% (CA) (p<0.0001); and for LSIL+ were 86.1% (EA) and 76.4% (CA) (p<0.0001). For ASC-US+, the sensitivities were not statistically different between the study arms at 58.1% (EA) and 59.2% (CA). Specificities were slightly greater in the CA for HSIL+ (97.7% (CA), 95.0% (EA) (p<0.0001)) and for LSIL+ (90.5% (CA), 85.6% (EA) (NS)), but slightly greater in the EA for ASC-US+ (82.5% (CA), 84.3% (EA) (NS)). NPV (CA/EA) for not-HSIL+ were 97.7/98.9% and for not-LSIL+ were 98.4/99.0%.
Conclusions: Use of the FocalPoint GS System significantly improved the sensitivity for detection of the important categories of squamous intraepithelial lesion (SIL) and cancer with a much smaller decrement in specificity. Detection of ASC-US+ cases was statistically equivalent, and improved SIL+ NPVs show performance of the device improves accuracy for clinically important entities without increasing equivocal case detection. Use of this device has the potential to significantly improve both accuracy and efficiency.
Tuesday, March 10, 2009 1:30 PM
Platform Session: Section F, Tuesday Afternoon