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Comparison of human papillomavirus distribution in cytologic subgroups of low-grade squamous intraepithelial lesion

2006; Wiley; Volume: 108; Issue: 5 Linguagem: Inglês

10.1002/cncr.22168

1097-0142

Rosemary E. Zuna, Sophia Wang, Mark Schiffman, Diane Solomon,

Genital Health and Disease

Cancer CytopathologyVolume 108, Issue 5 p. 288-297 Original ArticleFree Access Comparison of human papillomavirus distribution in cytologic subgroups of low-grade squamous intraepithelial lesion† Rosemary E. Zuna MD, Corresponding Author Rosemary E. Zuna MD [email protected] Pathology Department, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma Fax: (405) 271-6573.Pathology Department, BMSB 451, University of Oklahoma Health Sciences Center, Oklahoma City. OK 73104===Search for more papers by this authorSophia S. Wang PhD, Sophia S. Wang PhD Division of Cancer Epidemiology and Genetics, National Cancer Institute, Bethesda, MarylandSearch for more papers by this authorMark Schiffman MD, MPH, Mark Schiffman MD, MPH Division of Cancer Epidemiology and Genetics, National Cancer Institute, Bethesda, MarylandSearch for more papers by this authorDiane Solomon MD, Diane Solomon MD Division of Cancer Prevention, National Cancer Institute, Bethesda, MarylandSearch for more papers by this authorfor the Atypical Squamous Cells of Undetermined Significance/Low-Grade Squamous Intraepithelial Lesion Triage Study Group, for the Atypical Squamous Cells of Undetermined Significance/Low-Grade Squamous Intraepithelial Lesion Triage Study Group Affiliations of the Atypical Squamous Cells of Unknown Significance–Low-Grade Squamous Intraepithelial Lesion Triage Study Group: National Cancer Institute, Bethesda MD (D. Solomon, Project Officer; and M. Schiffman, Co-Project Officer); Clinical Centers: University of Alabama at Birmingham, AL (E. E. Partridge, Principal Investigator; L. Kilgore, Co-Principal Investigator; and S. Hester, Study Manager); University of Oklahoma, Oklahoma City, OK (J. L. Walker, Principal Investigator; G. A. Johnson, Co-Principal Investigator; and A. Yadack, Study Manager); Magee-Womens Hospital of the University of Pittsburgh Medical Center Health System, Pittsburgh, PA (R. S. Guido, Principal Investigator; K. McIntyre-Seltman, Co-Principal Investigator; R. P. Edwards, Investigator; and J. Gruss, Study Manager); University of Washington, Seattle, WA (N. B. Kiviat, Co-Principal Investigator; L. Koutsky, Co-Principal Investigator; and C. Mao, Investigator); Colposcopy Quality Control Group (D. Ferris, Principal Investigator [Medical College of Georgia, Augusta, GA]; J. T. Cox, Co-Investigator [University of California at Santa Barbara, Santa Barbara, CA]; and L. Burke, Co-Investigator [Beth Israel Deaconess Medical Center Hospital, Boston, MA]); Human Papillomavirus Quality Control Group (C. M. Wheeler, Principal Investigator [University of New Mexico Health Sciences Center, Albuquerque, NM]; C. Peyton-Goodall, Laboratory Manager [University of New Mexico Health Sciences Center, Albuquerque, NM]; and M. M. Manos, Co-Investigator [Kaiser Permanente, Oakland, CA]); Pathology Quality Control Group (R. J. Kurman, Principal Investigator [Johns Hopkins Hospital, Baltimore, MD]; D. L. Rosenthal, Co-Investigator [Johns Hopkins Hospital, Baltimore, MD]; M. E. Sherman, Co-Investigator [The National Cancer Institute, Rockville, MD]; and M. H. Stoler, Co-Investigator [University of Virginia Health Science Center, Charlottesville, VA]); Westat (Coordinating Unit [Rockville, MD]: J. Rosenthal, Project Director; M. Dunn, Data Management Team Leader; J. Quarantillo, Senior Systems Analyst; and D. Robinson, Clinical Center Coordinator; Quality of Life Group: D. M. Harper, Dartmouth Medical School [Hanover, NH]; A. T. Lorincz, Senior Scientific Officer [ Digene Corporation, Gaithersburg, MD]; and B. Kramer, Senior Programmer/Analyst [Information Management Services, Inc., Silver Spring, MD].Search for more papers by this author Rosemary E. Zuna MD, Corresponding Author Rosemary E. Zuna MD [email protected] Pathology Department, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma Fax: (405) 271-6573.Pathology Department, BMSB 451, University of Oklahoma Health Sciences Center, Oklahoma City. OK 73104===Search for more papers by this authorSophia S. Wang PhD, Sophia S. Wang PhD Division of Cancer Epidemiology and Genetics, National Cancer Institute, Bethesda, MarylandSearch for more papers by this authorMark Schiffman MD, MPH, Mark Schiffman MD, MPH Division of Cancer Epidemiology and Genetics, National Cancer Institute, Bethesda, MarylandSearch for more papers by this authorDiane Solomon MD, Diane Solomon MD Division of Cancer Prevention, National Cancer Institute, Bethesda, MarylandSearch for more papers by this authorfor the Atypical Squamous Cells of Undetermined Significance/Low-Grade Squamous Intraepithelial Lesion Triage Study Group, for the Atypical Squamous Cells of Undetermined Significance/Low-Grade Squamous Intraepithelial Lesion Triage Study Group Affiliations of the Atypical Squamous Cells of Unknown Significance–Low-Grade Squamous Intraepithelial Lesion Triage Study Group: National Cancer Institute, Bethesda MD (D. Solomon, Project Officer; and M. Schiffman, Co-Project Officer); Clinical Centers: University of Alabama at Birmingham, AL (E. E. Partridge, Principal Investigator; L. Kilgore, Co-Principal Investigator; and S. Hester, Study Manager); University of Oklahoma, Oklahoma City, OK (J. L. Walker, Principal Investigator; G. A. Johnson, Co-Principal Investigator; and A. Yadack, Study Manager); Magee-Womens Hospital of the University of Pittsburgh Medical Center Health System, Pittsburgh, PA (R. S. Guido, Principal Investigator; K. McIntyre-Seltman, Co-Principal Investigator; R. P. Edwards, Investigator; and J. Gruss, Study Manager); University of Washington, Seattle, WA (N. B. Kiviat, Co-Principal Investigator; L. Koutsky, Co-Principal Investigator; and C. Mao, Investigator); Colposcopy Quality Control Group (D. Ferris, Principal Investigator [Medical College of Georgia, Augusta, GA]; J. T. Cox, Co-Investigator [University of California at Santa Barbara, Santa Barbara, CA]; and L. Burke, Co-Investigator [Beth Israel Deaconess Medical Center Hospital, Boston, MA]); Human Papillomavirus Quality Control Group (C. M. Wheeler, Principal Investigator [University of New Mexico Health Sciences Center, Albuquerque, NM]; C. Peyton-Goodall, Laboratory Manager [University of New Mexico Health Sciences Center, Albuquerque, NM]; and M. M. Manos, Co-Investigator [Kaiser Permanente, Oakland, CA]); Pathology Quality Control Group (R. J. Kurman, Principal Investigator [Johns Hopkins Hospital, Baltimore, MD]; D. L. Rosenthal, Co-Investigator [Johns Hopkins Hospital, Baltimore, MD]; M. E. Sherman, Co-Investigator [The National Cancer Institute, Rockville, MD]; and M. H. Stoler, Co-Investigator [University of Virginia Health Science Center, Charlottesville, VA]); Westat (Coordinating Unit [Rockville, MD]: J. Rosenthal, Project Director; M. Dunn, Data Management Team Leader; J. Quarantillo, Senior Systems Analyst; and D. Robinson, Clinical Center Coordinator; Quality of Life Group: D. M. Harper, Dartmouth Medical School [Hanover, NH]; A. T. Lorincz, Senior Scientific Officer [ Digene Corporation, Gaithersburg, MD]; and B. Kramer, Senior Programmer/Analyst [Information Management Services, Inc., Silver Spring, MD].Search for more papers by this author First published: 11 October 2006 https://doi.org/10.1002/cncr.22168Citations: 9 † This article is a US Government work and, as such, is in the public domain in the United States of America. AboutSectionsPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Abstract BACKGROUND Low-grade squamous intraepithelial lesion (LSIL) subsumes the formerly delineated cytologic categories of human papillomavirus (HPV)-associated cell changes (koilocytotic atypia) and low-grade dysplasia/cervical intraepithelial neoplasia (CIN) Grade 1 (CIN1). In this study, the objective was to determine whether these 2 morphologic subcategories are characterized by differences in risk for CIN3 and/or HPV type distribution. METHODS Within the Atypical Squamous Cells of Undetermined Significance/Low-Grade Squamous Intraepithelial Lesion Triage Study, all cytologic interpretations of HPV cellular changes and CIN1 rendered by any of the pathology reviewers (community laboratory, clinical center, or Pathology Quality-Control Group) on referral Papanicolaou (Pap) tests or enrollment ThinPrep® Pap tests were included for analysis. HPV testing was performed by Hybrid Capture™ 2 (HC2) and by polymerase chain reaction based reverse-line blot analysis for 27 HPV types. The absolute risks of cumulative detection of CIN3 or cancer (CIN3 +) and CIN2 or worse (CIN2 +) over 2 years of follow-up were calculated for the various cytologic interpretations. RESULTS For each review group and cytology preparation, most LSIL interpretations (from approximately 2 of 3 interpretations to 3 of 4 interpretations) were subcategorized as CIN1 rather than HPV cellular changes. HPV type 16 (HPV-16) was the most common HPV type and was identified in 21% to 24% of CIN1 and in 14% to 18% of HPV cellular changes. Nononcogenic types were identified alone in from 9% to 11% of CIN1 compared with 17% to 20% of HPV cellular change. The absolute risks of CIN1 and HPV cellular changes for cumulatively detected CIN3 + ranged from 12% to 16% for CIN1 and from 6% to 9% for HPV cellular changes. CONCLUSIONS Both cytologic subcategories of LSIL were associated predominantly with oncogenic HPV types; however, the proportion of nononcogenic HPV types was lower and the absolute risks for CIN3 + were higher for CIN1 compared with HPV cellular changes. The concordance in subcategorizing LSIL was low, and the authors concluded that the diagnostic distinction is of limited clinical utility for individual patient management. Cancer (Cancer Cytopathol) 2006 Published 2006 by the American Cancer Society. With their seminal descriptions of koilocytotic atypia in the squamous epithelium of the cervix, Koss and Durfee1 and Ayre2 suggested the possibility of a viral association with premalignant lesions of the cervix. Meisels et al.3, 4 further identified the "balloon" cell or koilocyte as the primary cytologic manifestation of the flat condylomata and stressed the importance in distinguishing those lesions from mild dysplasia (cervical intraepithelial neoplasia Grade 1 [CIN1]). Early terminology distinctions between "koilocytic atypia" and mild dysplasia were based on the belief that viral infection was distinct etiologically from carcinogenesis and that mild dysplasia was the true early precursor lesion to cervical cancer. Since then, however, a group of 13 to 15 human papillomaviruses (HPV) types have been recognized as oncogenic; and, today, it is well accepted that HPV is unequivocally the etiologic agent for cervical cancer and its precursors.5-7 Although koilocytotic changes are accepted as HPV-induced abnormalities,8, 9 their risk relative to CIN1 for a subsequent diagnosis of cervical precancer still is debated. In some countries, the distinction still is made in daily practice. The morphologic characteristic of cellular changes of HPV (HPV changes) (also known as "koilocytotic atypia") is the perinuclear clearing or halo, which is devoid of organelles and is surrounded by a dense, cytoplasmic rim filled with tonofilaments.10-13 Studies attempting to distinguish HPV changes from CIN1 have shown similar biology and lack of diagnostic reproducibility for separating these categories.14, 15 Consequently, the Bethesda System of cytologic classification, which was defined originally in 198816, 17 and revised in 2001,18 combined lesions that were described as HPV changes with lesions that were diagnosed as CIN1 into a single category known as low-grade squamous intraepithelial lesion (LSIL). A significant amount of new information is now available regarding HPV types and their categorization by oncogenicity.6, 19-21 The objective of the current study, which was conducted within the Atypical Squamous Cells of Undetermined Significance (ASCUS)/LSIL Triage Study (ALTS), a multicenter, randomized clinical trial that compared management strategies for low-grade and equivocal cytologic categories, was to investigate the distribution of HPV types comprehensively within the 2 morphologic patterns of LSIL-HPV changes and CIN1- and to identify any differences in the risk for CIN3 or HPV type distribution. MATERIALS AND METHODS Study Population The structure of ALTS has been described previously.22 Briefly, enrollment was offered to women who were referred from the community with ASCUS or LSIL conventional Papanicolaou (Pap) smear interpretations from November 1996 through December 1998 at 4 clinical centers: the University of Alabama (Birmingham, AL), Magee-Womens Hospital of the University of Pittsburgh Medical Center Health System (Pittsburgh, PA), the University of Oklahoma (Oklahoma City, OK), and the University of Washington (Seattle, WA). Written informed consent was obtained from each participant. At enrollment, cervical specimens and complete questionnaire data, including demographic, hormone, and sexual histories, were collected. The current analysis included all women who were diagnosed with LSIL in referral and/or enrollment cytology specimens, as specified below. Women were followed every 6 months for 2 years for disease outcomes of histologic CIN2 or worse (CIN2 +) and CIN3 or cancer (CIN3 +). Because CIN2 is the community threshold for treatment, we considered the clinical center diagnosis of CIN2 + as 1 outcome, and the Pathology Quality-Control (QC) group review diagnosis for the more stringent outcome of CIN3 + as a true precancer state. Definition of LSIL On average, women were enrolled into ALTS 2 months after the original abnormal Pap test result of ASCUS or LSIL ("referral Pap"). At enrollment, a liquid-based cytology specimen (ThinPrep®; Cytyc Corporation, Marlborough, MA) was collected with a broom-type sampler (Papette™ broom; Wallach Surgical Devices, Incorporated, Orange, CT) and transferred to a PreservCyt® vial (Cytyc Corporation). A second cervical specimen was then collected using a Dacron swab and placed into Specimen Transport Medium™ (STM) (Digene Corporation, Gaithersburg, MD), which was used for the prototype linear-array polymerase chain reaction (PCR) HPV DNA typing (see below). The referral Pap smears were read by the community laboratory, and the enrollment ThinPrep Pap tests initially were interpreted by a clinical site pathologist; both the referral smears and the enrollment ThinPrep Pap tests were then reviewed by the Pathology QC Group.22, 23 Therefore, for each woman, there were 4 independently rendered cytologic interpretations: 1) the community laboratory interpretation of the original referral Pap smear (which was always ASCUS or LSIL, according to the enrollment eligibility criteria); 2) the Pathology QC Group masked review of the original referral Pap smear; 3) the clinical center interpretation of the enrollment ThinPrep test; and 4) the Pathology QC masked review of the enrollment ThinPrep test. In total, 2546 women were identified with LSIL by any 1 or more of the 4 interpretation groups, including 2371 women for whom HPV data were available.23 Those 2371 women constitute the population for this study, whereas the remaining 175 women without HPV data were excluded. Cytologic Definition of HPV Changes and CIN1 For research purposes and data collection, the broad category of LSIL was divided into 3 subcategories: 1) LSIL, not otherwise specified (NOS); 2) LSIL, cellular changes of HPV; and 3) LSIL, CIN1. For the current analysis, we considered that "LSIL, cellular changes of HPV" (HPV changes) was analogous to the previously used term "koilocytotic atypia" and that "LSIL, CIN1" (CIN1) was analogous to mild dysplasia/CIN1. Because only 4% of LSIL interpretations overall were NOS, as indicated in Table 1, this subcategory was not included in subsequent analyses. Table 1. Distribution of Cervical Intraepithelial Neoplasia Grade 1and Human Papillomavirus (HPV) Changes among Varying Definitions of HPV Statusby 4 Distinct Definitions: for Low-Grade Intraepithelial Squamous Lesion: Original Referral Papanicolaou (Pap) Test (Conventional)Interpretation at the Clinical Site, Pathology Quality-Control Review Interpretation of the Original Pap Test, Clinical CenterInterpretation of the enrollment ThinPrep® Pap Test, and Pathology Quality-Control Review of the Enrollment ThinPrep® Pap Test Diagnosis No. of patients (%) HC2-positive HC2-negative Chi-square P value PCR:HPV16 PCR:Oncogenic, Non-HPV16 PCR-positive, nononcogenic PCR-negative PCR:HPV16 PCR:Oncogenic, Non-HPV16 PCR-positive, Nononcogenic PCR-negative Original referral Pap (conventional) interpretation at the clinical sites (n = 1476)* CIN1 (n = 1262) 273 (22) 628 (50) 95 (8) 71 (6) 6 (0) 17 (1) 37 (3) 135 (11) HPV† (n = 178) 26 (15) 80 (45) 25 (14) 15 (8) 2 (1) 1 (1) 9 (5) 20 (11) .009 Path QC review interpretation of the original Pap (n = 1283)‡ CIN1 (n = 1067) 228 (21) 546 (51) 88 (8) 53 (5) 4 (0) 18 (2) 35 (3) 95 (9) HPV&†(n = 212) 29 (14) 94 (44) 32 (15) 13 (6) 2 (1) 5 (2) 10 (5) 27 (13) .003 Clinical center interpretation of the enrollment ThinPrep® Pap (n = 1244)§ CIN1 (n = 675) 163 (24) 372 (55) 45 (7) 28 (4) 0 (0) 3 (0) 12 (2) 52 (8) HPV&†(n = 412) 74 (18) 228 (55) 64 (16) 24 (6) 1 (0) 5 (1) 5 (1) 11 (3) <.0001 Path QC review of the enrollment ThinPrep® (n = 1196)| CIN1 (n = 931) 215 (23) 532 (57) 86 (9) 45 (5) 0 (0) 3 (0) 16 (2) 34 (4) HPV&†(n = 254) 42 (17) 141 (56) 41 (16) 13 (5) 0 (0) 7 (3) 5 (2) 5 (2) <.0001 HC2 indicates Hybrid Capture 2; PCR, polymerase chain reaction; HPV, human papillomavirus; HPV cellular changes, Pap, Papanicolaou; CIN1, cervical intraepithelial neoplasia Grade 1; Path QC, pathology quality control. * Low-grade squamous intraepithelial lesion, not otherwise specified (LSIL, NOS), n = 36 women; missing, n = 96 women. † HPV refers to HPV cellular changes. ‡ LSIL, NOS in 4 women; data missing for 89 women. § LSIL, NOS in 57 women; data missing for 98 women. | LSIL, NOS in 11 women; data missing for 94 women. The clinical center and Pathology QC pathologists applied criteria that were based largely on the Bethesda System17 to distinguish HPV changes from CIN1. Cells with well defined cytoplasmic halos and thickened cytoplasmic rims in association with only mild nuclear changes—nuclear enlargement, hyperchromasia, and/or smudged chromatin—were interpreted as HPV changes (Fig. 1).4 In contrast, the cases that were categorized as CIN1 demonstrated some superficial squamous cells with nuclei that were at least 3-fold the size of a normal intermediate cell nucleus and hyperchromatic. Perinuclear halos could be present as long as the nuclear enlargement and hyperchromasia were sufficient for dysplasia. Figure 1Open in figure viewerPowerPoint These photomicrographs of representative cells illustrate the diagnostic categories that were used for low-grade squamous intraepithelial lesions in the current study (modified Papanicolaou stain; original magnification × 63). (A) Human papillomavirus cellular changes and (B) cervical intraepithelial neoplasia of Grade 1. HPV Testing Two types of HPV tests were used in this study. The PreservCyt sample was used for the Hybrid Capture 2™ (HC2) test with the high-risk probe (Probe B), which targets the following oncogenic HPV types: HPV type (HPV-16), HPV-18, HPV-31, HPV-33, HPV-35, HPV-39, HPV-45, HPV-51, HPV-52, HPV-56, HPV-58, HPV-59, and HPV-68.24 DNA isolated from the STM samples was analyzed for individual HPV genotype(s) by using a PCR-based reverse-line blot technique25, 26 (Roche Molecular Systems, Alameda, CA), which utilizes biotinylated PGMY09/PGMY11 consensus primers that amplify a 450-base pair fragment of HPV L1 open reading frame for a large number of HPV types. This approach can identify 1 or more of 27 individual HPV types in a single test. Included in this test are primers for oncogenic HPV types HPV-16, HPV-18, HPV-31, HPV-33, HPV-35, HPV-39, HPV-45, HPV-51, HPV-52, HPV-56, HPV-58, HPV-59, and HPV-68; nononcogenic HPV types HPV-6, HPV-11, HPV-26, HPV-40, HPV-42, HPV-53, HPV-54, HPV-55, HPV-57, HPV-66, HPV-73, HPV-82, HPV-83, and HPV-84; and β-globin DNA as an internal standard.24 Tests with multiple HPV types were considered to be oncogenic if at least 1 oncogenic HPV type was identified or nononcogenic if only nononcogenic types were identified. We evaluated viral load by using HC2 signal-strength measurements (in relative light units [RLU]), which were related linearly to the number of HPV copies and converted to pg/mL of HPV DNA.27, 28 All cytologic interpretations and HPV tests were performed independently without knowledge of the other results. Because it was proposed recently that HPV-66 is an oncogenic type,20, 21 we also conducted all analyses with HPV-66 included as an oncogenic type and observed minimal impact on our results. Similarly, the inclusion of HPV-26, HPV-73, and/or HPV-82 as oncogenic types did not alter our results. Statistical Methods Within each of the 4 interpretation groups identified above, we compared the distribution (numbers and percentages) of women who were diagnosed with CIN1 or HPV changes according to the different review groups by using κ statistics and the McNemar test for asymmetry. We also compared the distribution of women who were diagnosed with CIN1 or HPV changes according to their HPV status. HPV status first was dichotomized as HC2-positive or HC2-negative; then, it was stratified further by the following risk categories based on PCR results: HPV-16-positive; any oncogenic HPV-positive, excluding HPV-16; oncogenic HPV-negative, nononcogenic HPV-positive; and HPV-negative by PCR. Differences in the distribution of HPV status between CIN1 and HPV changes were quantified by using the Fisher exact test for significance. P values (2-tailed) ≤.05 were considered statistically significant. This analysis was repeated for each of the 4 categories of cytologic interpretation. Oncogenic and nononcogenic HPV type distribution between CIN1 and HPV changes was delineated further. Absolute risks (or positive predictive value) for disease outcomes of CIN2 +, as defined by the clinical center pathologists, and for CIN3 +, as defined by the Pathology QC Group, were calculated. All results presented are stratified by the 4 cytologic interpretations and by HPV status. RESULTS We analyzed LSIL interpretations, subcategorized as HPV changes or CIN1, that were rendered by 4 independent reviews: 1) the community laboratory interpretation of the original referral Pap test; 2) the Pathology QC review of the original referral Pap test; 3) the clinical center interpretation of the enrollment ThinPrep Pap test; and 4) the Pathology QC review of the enrollment ThinPrep Pap test. These reviews define the 4 different definitions of LSIL. Most LSIL interpretations (from approximately 2 of 3 interpretations to 3 of 4 interpretations) were subcategorized as CIN1 rather than cellular changes of HPV. The percentages of LSIL categorized as CIN1 or HPV changes, however, varied within the 4 interpretation groups of LSIL (Table 1). Among women who had interpretations of LSIL on their original referral Pap test (n = 1476 women), 86% and 12% were identified as CIN1 and HPV changes, respectively; among women who had interpretations of LSIL in the Pathology QC review of the referral Pap test (n = 1283 women), 83% and 17% were identified as CIN1 and HPV changes, respectively; among women who had interpretations of LSIL in the clinical center review of their ThinPrep Pap test (n = 1244 women), 65% and 33% were identified as CIN1 and HPV changes, respectively; and, among women who had interpretations of LSIL in the Pathology QC review of their ThinPrep Pap test (n = 1196 women), 78% and 21% were identified as CIN1 and HPV changes, respectively. There was moderate agreement (77%) on the Pathology QC interpretations of CIN1 and HPV changes for the original referral Pap test compared with the paired ThinPrep Pap test from the same women (κ = .2). However, agreement was poor (37%) between interpretations that were made by the community laboratory and the clinical center; and, in general, those interpretations were more severe than the interpretations made by the Pathology QC group (κ < .05; McNemar P = .001). Therefore, in this report, we present the results from all 4 cytologic interpretations. In total, 2546 women were diagnosed with LSIL (HPV cellular changes or CIN1) by ≥1 of the 4 pathology interpretations. Of 827 women who were diagnosed with HPV changes by any of the 4 interpretations, only 4 women (<1%) had results that were identified as HPV changes according to 4 interpretations; 45 women (5%) had results that were identified as HPV changes according to 3 interpretations, 211 women (26%) had results that were identified as HPV changes according to 2 interpretations, and 567 women (69%) had results that were identified as HPV changes according to a single interpretation. Similarly, of 2312 women who were diagnosed with CIN1 by any of the 4 interpretations, 129 women (6%) had results that were identified as CIN1 according to all 4 interpretations; 359 women (16%) had results that were identified as CIN1 according to 3 interpretations, 788 women (34%) had results that were identified as CIN1 according to 2 interpretations, and 1036 women (45%) had results that were identified as CIN1 according to a single interpretation. For all interpretations of LSIL (i.e., Table 1), the HPV risk category (according to the HC2 and PCR results) varied significantly between CIN1 and HPV changes, as measured with the Fisher exact test. CIN1 was associated with a higher percentage of HC2-positive/PCR HPV-16-positive resutls (21–24%) compared with HPV changes (14–18%). CIN1 also showed a higher percent of HC2-positive/PCR oncogenic type-positive (HPV-16-negative) results compared with HPV changes, but only for the referral smear interpretations and not for the enrollment ThinPrep cytology. The percentage of HC2-positive women who had nononcogenic types identified by PCR was much lower than the percentage of HC2-positive women who had oncogenic types identified by PCR. The relative numbers differed notably for HPV changes and CIN1 diagnoses. The percentage of nononcogenic HPV-positive women ranged from 7% to 9% for women who had an interpretation of CIN1 and was nearly 2-fold higher for women who had HPV changes (14–16%) for all interpretation groups. The numbers of tests that had discordant HC2 results and PCR results were small and accounted for 6% to 15% of all CIN1 and HPV changes (Table 1). Specifically, there were a few women in all categories who had HC2-positive results but HPV-negative PCR results (4–8%) or HC2-negative results but HPV-positive PCR results for either oncogenic or nononcogenic types (2–8%).29 The remaining 2% to 13% of women had HC2-negative results and PCR-negative results, as described in full previously.23 Higher percentages of referral smear interpretations were HPV-negative according to both HC2 and PCR results compared with the ThinPrep interpretation, presumably because of the resolution of some HPV infections in the interval between the referral smear and the enrollment specimen collections (on average, ≈2 months later) used for ThinPrep and HPV testing. The absolute risks or positive predictive values for developing CIN3 + within the 2-year follow-up are shown in Table 2. The absolute risk was highest for the women with HC2-positive/HPV-16-positive CIN1 results across all 4 cytologic interpretation groups (range, 28.4–39.9%). The absolute risk for women who had HPV changes and the same HPV risk status ranged from 17.2% to 34.6%. For women who had HC2-positive results and PCR-positive results for oncogenic HPV types other than HPV-16, the absolute risks for developing CIN3 + were substantially lower for both CIN1 (range, 8.5–11.9%) and HPV changes (range, 2.8–5.7%) (Table 2). The absolute risks for women who had HC2-positive results and nononcogenic HPV-positive PCR results were lower still (CIN1: range, 3.5–4.6%; HPV changes: range, 1.6–4.0%). Table 2. The Absolute Risk for a Diagnosis of Cervical Intraepithelial Neoplasia Grade 3 or Worse by Expert Pathology Review According to CervicalIntraepithelial Neoplasia Grade 1 and Human Papillomavirus (HPV) Changes among Various Definitions of HPV Status According toDistinct Definitions for Low-Grade Squamous Intraepithelial Lesion: Original Referral Papanicolaou (Pap) Test (Conventional)Interpretation at the Clinical Site, Pathology Quality-Control Review Interpretation of the Original Pap Test, Clinical CenterInterpretation of the enrollment ThinPrep® Pap Test, and Pathology Quality-Control Review of the Enrollment ThinPrep® Pap Test Diagnosis Absolute risk (range), % Total HC2-positive HC2-negative PCR:HPV-16 PCR:Oncogenic, non-HPV-16 PCR-Positive, Nononcogenic PCR-negative PCR:HPV-16 PC