Anatomic Pathology / DNA PLOIDY IN NORMAL SMEARS WITH HIGH-RISK HUMAN PAPILLOMAVIRUS

To improve the positive predictive value (PPV) for high-risk human papillomavirus (HR-HPV) in primary screening, DNA ploidy was measured on the same liquid-based sample by image cytometry in 984 cases showing discrepancies between cytology and HR-HPV testing. Of the conflicting results, 14.5% corresponded to a cytologic lesion (from atypical squamous cells of undetermined significance to high-grade squamous intraepithelial lesion [HSIL]) without HPV detected, and 85.5% of smears were within normal limits but revealed an HR-HPV infection. A suspect DNA profile was associated significantly with a lesion. In 497 patients who underwent repeated HPV testing, a normal DNA profile at the first smear predicted the clearance of HPV infection (sensitivity, 81.5%; specificity, 45.4%; PPV, 69%; negative predictive value, 62.4%). In persistent HR-HPV infection, a suspect DNA profile at the first smear increased the PPV from 10.8% to 22.7% for the detection of a histologically proven HSIL with a sensitivity of 95.2%. DNA ploidy can be used to select smears with high risk of HSIL, especially in cases of persistent HR-HPV infection. At present, screening of cervical cancer is based on the detection of cytomorphologically abnormal cells. Detection has been improved by the use of liquid-based cytology methods. These methods offer some advantages in comparison with conventional Papanicolaou (Pap) smears. In particular, they reduce problems related to sampling errors1 and increase the proportion of satisfactory examinations according to the Bethesda System2 and the number of positive diagnoses3 (high-grade squamous intraepithelial lesion [HSIL], low-grade squamous intraepithelial lesion [LSIL], and atypical squamous cells of undetermined significance [ASCUS]). Numerous studies have reported that liquid-based cytology is more accurate than conventional cytology and has the potential to optimize the effectiveness of primary cervical cancer screening.4-7 However, even if the number of falsenegative results has decreased with the use of liquid-based cytology, the sensitivity of cervical cancer screening still can be improved with the development of new approaches such as high-risk human papillomavirus (HR-HPV) testing and DNA ploidy measurement, which can be done on the same sample. It is well established that HR-HPV infection is a necessary but not sufficient condition for cervical carcinogenesis.8-11 Indeed, HR-HPV types have been detected in 99.7% of invasive cervical carcinomas.10 Moreover, HR-HPV infections are associated with a relative risk of between 8 and 11 for the development of SIL,12 and essentially LSILs containing HR-HPV progress to HSIL.13 Because of this, the use of HR-HPV testing in primary screening is proposed by some authors. A recent study of 7,932 females demonstrated that the sensitivity of HPV testing for detecting a histologically proven HSIL was dramatically higher than that of conventional and liquid-based cytology.14 However, in the Anatomic Pathology / ORIGINAL ARTICLE Am J Clin Pathol 2002;118:708-713 709 © American Society for Clinical Pathology experience of Clavel et al,14 the specificity and positive predictive value of HPV testing for detecting HSIL remained low at 85.6% and 9.3%, respectively. The high incidence (about 10% in our study14) of HR-HPV infection in females with normal smears is largely responsible for that. Thus, the use of additional biomarkers would be of great help to select more specifically the smears of patients in whom HSIL could develop. It is well established that lesions in which cervical cells have an aneuploid DNA profile are more likely to persist or progress than those with diploid or polyploid profiles.15-20 Indeed, Lorenzato et al21 reported that DNA ploidy measurement by image cytometry on conventional cervical smears positive for HR-HPV could help detect females at high risk for the development of HSIL. Nevertheless, the major bias in that previous work was that the 3 variables (cytology, HPV testing, and DNA measurement) were evaluated on 3 different samples. This could explain some discrepancies observed between results obtained with conventional cytology and DNA measurement. Because the cells in suspension in the preservation medium represent a general representative cell population, the lack of reproducibility between smears for cytology, DNA measurement, and HPV testing could be overcome by the use of liquid-based cytology. Cytologic abnormalities suggestive of a lesion in a smear with a concomitant HR-HPV infection generally are confirmed by the histologic examination. The major problems concern the management of cervical smears within normal limits with HR-HPV infection (about 10% in our experience) and cervical lesions without detectable HR-HPV. Thus, our aim was to study the usefulness of DNA image cytometry in such cases with conflicting results between cytology and HR-HPV testing, using a unique sample. Materials and Methods The study concerned a total of 7,949 liquid-based cytology specimens submitted for HR-HPV testing with the Hybrid Capture II (HC-II; Digene, Gaithersburg, MD) test. Of these, results for a total of 984 females with a median age of 39 years (range, 15-87 years) showed conflicting results for the 2 tests and underwent DNA ploidy analysis. This population included females undergoing their triennial routine screening in the Department of Obstetrics and Gynecology of the University Hospital of Reims, Reims, France. All were informed of the aim of the study and gave their consent.