Evelyn P. Whitlock, MD, MPH; Kimberly K. Vesco, MD, MPH; Michelle Eder, PhD; Jennifer S. Lin, MD, MCR; Caitlyn A. Senger, MPH; Brittany U. Burda, MPH
Acknowledgment: The authors thank Daphne Plaut, MLS, for conducting the literature searches; Kevin Lutz, MFA, for editorial support; and Rebecca Holmes, MD, MS, and Sarah Zuber, MSW, for assistance in conducting the evidence review. They also thank the Agency for Healthcare Research and Quality and the USPSTF and Marc Arbyn, MD, MSc, DrTMH; Walter Kinney, MD; Mary Mitchell; Alan G. Waxman, MD, MPH; and Diana Petitti, MD, MPH, for their contribution to this evidence review.
Grant Support: This review was conducted by the Oregon Evidence-based Practice Center under contract to the Agency for Healthcare Research and Quality (contract HHS-290-2007-10057-I, task order 3).
Potential Conflicts of Interest: Drs. Whitlock, Vesco, Eder, and Lin and Ms. Senger: Grant (money to institution): Agency for Healthcare Research and Quality; Support for travel to meetings for the study or other purposes (money to institution): Agency for Healthcare Research and Quality; Payment for writing or reviewing the manuscript (money to institution): Agency for Healthcare Research and Quality. Drs. Whitlock, Eder, and Lin and Ms. Senger: Provision of writing assistance, medicines, equipment, or administrative support (money to institution): Agency for Healthcare Research and Quality. Ms. Senger: Support for travel to meetings for the study or other purposes (money to institution): National Institutes of Health. Ms. Burda: Grant (money to institution): Agency for Healthcare Research and Quality; Support for travel to meetings for the study or other purposes (money to institution): Agency for Healthcare Research and Quality; Consultancy: Oregon Health & Science University. Disclosures can also be viewed at www.acponline.org/authors/icmje/ConflictOfInterestForms.do?msNum=M11-1382.
Requests for Single Reprints: Reprints are available from the Agency for Healthcare Research and Quality Web site (www.preventiveservices.ahrq.gov).
Current Author Addresses: Drs. Whitlock, Vesco, Eder, Lin, and Senger and Ms. Burda: Center for Health Research, Kaiser Permanente Northwest, 3800 North Interstate Avenue, Portland, OR 97227.
Author Contributions: Conception and design: E.P. Whitlock, K.K. Vesco.
Analysis and interpretation of the data: E.P. Whitlock, K.K. Vesco, M. Eder, J.S. Lin.
Drafting of the article: E.P. Whitlock, K.K. Vesco, M. Eder, C.A. Senger.
Critical revision of the article for important intellectual content: E.P. Whitlock, K.K. Vesco, J.S. Lin, C.A. Senger.
Final approval of the article: E.P. Whitlock, K.K. Vesco, M. Eder, J.S. Lin.
Obtaining of funding: E.P. Whitlock.
Administrative, technical, or logistic support: C.A. Senger, B.U. Burda.
Collection and assembly of data: K.K. Vesco, M. Eder, J.S. Lin, C.A. Senger, B.U. Burda.
Whitlock EP, Vesco KK, Eder M, Lin JS, Senger CA, Burda BU. Liquid-Based Cytology and Human Papillomavirus Testing to Screen for Cervical Cancer: A Systematic Review for the U.S. Preventive Services Task Force. Ann Intern Med. 2011;155:687-697. doi: 10.7326/0003-4819-155-10-201111150-00376
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Published: Ann Intern Med. 2011;155(10):687-697.
This article has been corrected. The original version (PDF) is appended to this article as a supplement.
Screening programs using conventional cytology have successfully reduced cervical cancer, but newer tests might enhance screening.
To systematically review the evidence on liquid-based cytology (LBC) and high-risk human papillomavirus (HPV) screening for U.S. Preventive Services Task Force use in updating its 2003 recommendation.
MEDLINE, Cochrane Central Register of Controlled Trials, and PsycINFO from January 2000 through September 2010.
Two independent reviewers selected fair- to good-quality English-language studies that compared LBC or HPV-enhanced primary screening with conventional cytology in countries with developed population-based screening for cervical cancer.
At least 2 independent reviewers critically appraised and rated the quality of studies and used standardized abstraction forms to extract data about test performance for detecting cervical intraepithelial neoplasia (CIN) and cancer and screening-related harms.
On the basis of 4 fair- to good-quality studies (141 566 participants), LBC had equivalent sensitivity and specificity to conventional cytology. Six fair- to good-quality diagnostic accuracy studies showed that 1-time HPV screening was more sensitive than cytology for detecting CIN3+/CIN2+ but was less specific. On the basis of 2 fair- to good-quality randomized, controlled trials (RCTs) (120 533 participants), primary HPV screening detected more cases of CIN3 or cancer in women older than 30 years. Four fair- to good-quality diagnostic accuracy studies and 4 fair- to good-quality RCTs showed mixed results of cotesting (HPV plus cytology) in women aged 30 years or older compared with cytology alone, with no clear advantage over primary HPV screening. Incomplete reporting of results for all screening rounds, including detection of disease and colposcopies, limits our ability to determine the net benefit of HPV-enhanced testing strategies.
Resources were insufficient to gather unpublished data, short-term trial data showed possible ascertainment bias, and most RCTs used protocols that differed from current U.S. practice.
Evidence supports the use of LBC or conventional cytology for cervical cancer screening, but more complete evidence is needed before HPV-enhanced primary screening is widely adopted for women aged 30 years or older.
Agency for Healthcare Research and Quality.
Several techniques may be used to screen for cervical cancer.
This systematic review focused on screening for women aged 30 years or older. Liquid-based cytology and conventional cytology had similar sensitivity and specificity for detecting cervical intraepithelial neoplasia. One-time human papillomavirus (HPV) testing was more sensitive but less specific than cytology. The overall harms and costs of work-up for false-positive HPV test results were unclear.
Liquid-based and conventional cytology seem interchangeable for cervical cancer screening. Substituting a strategy of HPV screening (with or without cytology triage for positive test results) seems promising but needs evaluation in long-term, large trials.
Summary of evidence search and selection.
CC = conventional cytology; HPV = human papillomavirus; LBC = liquid-based cytology.
Table 1. Results of Liquid-Based Cytology Studies
Table 2. Absolute Test Performance of Primary Screening With HPV Testing Alone and Combination HPV and Cytology Screening in Developed Countries in Women Aged 30 Years or Older
Table 3. Results From Randomized, Controlled Trials of HPV Screening Strategies in Cervical Cancer Screening in Women 30 Years or Older
Appendix Table. Characteristics of Randomized, Controlled Trials of HPV Screening Strategies for Cervical Cancer Screening
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Video News Release - Editor, Christine Laine, Explains Results of Women's Cancer Studies
Carlo A.Liverani, Chief of Preventive Gynecologic Oncology Unit
Policlinico Hospital, University of Milano (Italy)
October 28, 2011
Just to say thank you
An honest work, very useful to understand what is specultive and what is really needed
GuglielmoRonco, Epidemiologist, Chris JL Meijer (VUMC University, Amsterdam, the Netherlands), Jack Cuzick (Queen Mary University, London, UK), Paolo Giorgi-Rossi (ASP Lazio, Rome, Italy), Julian Peto (London School of Hygiene, London, UK), Nereo Segnan (CPO, Turin, Italy ), Joakim Dill
Center for Cancer Prevention (CPO) , Turin, Italy
November 11, 2011
HUMAN PAPILLOMAVIRUS TESTING TO SCREEN FOR CERVICAL CANCER
The USPSTF report(1) has evaluated the use of HPV testing and cytology in cervical cancer screening and concluded that more evidence is needed to determine the optimal approach. The report has considered the different possible strategies separately (HPV alone, HPV alone with cytology triage, co-testing, co-testing with cytology triage) in comparison to cytology only and considered solely results on prevention of invasive cancer.
It has been conclusively shown that HPV testing is able to detect about 50% more high-grade CIN, an established cancer precursor, than cytology(2) at an initial screening . Furthermore, all RCTs conducted in industrialized countries(3-6) have shown a similar reduction in CIN3+ after HPV testing (table 3 of the report) indicating that HPV testing is able to detect non-regressive lesions earlier than cytology, thereby reducing precancerous lesions in subsequent screening rounds. This lead- time gain was similar for all strategies studied. In addition, a pooled analysis of phase 1 (co-testing) and phase 2 (HPV alone) of the NTCC(6) trial also showed a major, clinically important and statistically significant reduction in invasive cancers. As different strategies using HPV testing have shown similar results, pooling data is not only reasonable but very much needed. As the protective effect is similar with all strategies, the least costly (HPV testing with cytology triage) should be chosen. As this strategy has the same need for colposcopy as cytology only(3,4), lack of data on colposcopies needed for other strategies is not relevant for costs (and obviously not for effectiveness).
The report also contains factual mistakes. For example, it is stated that "ARTISTIC had the opposite result: more cases of cancer were found after 2 screening rounds in the cotesting group (8 total) compared with cytology (4 total)". In this trial (5), there were proportionally more cancers with cytology because the cotesting: cytology randomization ratio was 3:1.
Further, the report considers quality issues used in pharmacological trials that are clearly irrelevant for large preventive trials. For example, masking patients is plausibly irrelevant when evaluating preventive programs where patient information is a vital part of the intervention itself and when the disease is asymptomatic and placebo effects unlikely. Observer bias is more plausible, but all trials had a blind assessment of the clinical endpoint.
Already in 2008, the EU guidelines(7) on cervical cancer screening concluded that existing evidence is sufficient at least for the launch of controlled pilot implementation projects using HPV screening. This could provide additional evidence on cancer-protective effect, but only after many years. In our view, requiring new RCTs with cancer incidence as the endpoint to compare with cytology every small variation (like triage methods) in HPV-based screening strategies is unreasonable, unsustainable and, given the time-frame of acquiring evidence, also unethical.
1. Whitlock EP, Vesco KK, Eder M, Lin JS, Senger CA, Burda BU. Liquid -Based Cytology and Human Papillomavirus Testing to Screen for Cervical Cancer: A Systematic Review for the U.S. Preventive Services Task Force. Ann Intern Med 2011 [PM:22006930].
2. Cuzick J, Arbyn M, Sankaranarayanan R, Tsu V, Ronco G, Mayrand MH, Dillner J, Meijer CJL. Overview of human papillomavirus-based and other novel options for cervical cancer screening in developed and developing countries. Vaccine 2008; 26S:K29-41.
3. Naucler P, Ryd W, Tornberg S, et al. Human papillomavirus and Papanicolau tests to screen for cervical cancer. N Engl J Med 2007; 357: 1589-97.
4. Bulkmans N, Berkhof J, Rozendaal L, et al. Human papilllomavirus DNA testing for the detection of cervical intraepithelial neoplasia grade 3 and cancer: 5-year follow-up of a randomised controlled implementation trial. Lancet 2007 24; 370: 1764-72.
5. Kitchener HC, Almonte M, Thomson C, et al. HPV testing in combination with liquid-based cytology in primary cervical screening (ARTISTIC): a randomised controlled trial. Lancet Oncol 2009; 10: 672-82.
6. Ronco G, Giorgi-Rossi P, Carozzi F, Confortini M, Dalla Palma P, Del Mistro A et al. Efficacy of human papillomavirus testing for the detection of invasive cervical cancers and cervical intraepithelial neoplasia: a a randomised controlled trial. Lancet Oncol 2010; 11:249-57.
7. Arbyn M, Anttila A, Jordan J, .Ronco G, Schenck U, Segnan N, Wiener H, eds. European guidelines for quality assurance on cervical cancer screening. 2nd edition . Luxembourg: Office for Official Publications of the European Communities, 2008.
No conflict of interest for G Ronco, P Giorgi-Rossi, J Peto, N Segnan and J Dillner. Member scientific advisory board of Qiagen and occasional consultant for GSK, Merck, and Roche (CJL Meijer) His institution receives support from Abbott, Becton Dickinson, GenProbe, Qiagen and Roche to evaluate HPV tests and he isoccasional consultant for these companies (J Cuzick).
EvelynWhitlock, MD, MPH, Kimberly K. Vesco, MD, MPH, Michelle Eder, PhD; Jennifer S. Lin, MD, MCR; Caitlyn A. Senger, MPH, Brittany U. Burda, MPH
Oregon Evidence-based Practice Center, Center for Health, Research, Kaiser Permanente Northwest, Por
November 17, 2011
To the Editor:
1. We have a revision of the first full paragraph on p. 693 (vol. 155:10) that accurately compares detection by cotesting against cytology alone with more detail about interpretation. Please include this paragraph as a correction to our published paragraph. Four large, fair-quality RCTs compared cotesting with cytology screening alone in European women aged30 to 64 years (Table 3). (46-49) These 4 studies included NTCC phase 1, POBASCAM, Swedescreen, and ARTISTIC, and comprised 82,390 participants. In contrast to HPV screening alone, cotesting did not detect more CIN3+ after 2 screening rounds than cytology alone (Table 3). Round-specific screening results were not completely consistent. Generally, cotesting detected relatively more CIN2+ (and sometimes CIN3+) after 1 screening round, compared with cytology alone. Cotesting identified lessCIN3+ (and, where reported, cancers) after the second round, tending toward fewer cancers cumulatively.
Interpreting these mixed results is complicated by: 1) uncertainty about the completeness of outcome ascertainment for cancers and high-grade precancers due to between-trial differences in duration and completeness of follow-up for the entire screened population and screening episode (Appendix Table,Vesco 2011 (15)); 2) lack of consensus on the appropriate surrogate outcome (Vesco 2011 (15) Table 17),with possible asymmetry bias due to limited long-term follow-up (1); and 3) screening protocol differences (Table 3, Appendix Table) between trials and with US practice.
2. We would also like to correct two citation errors in the first paragraph in the right column of p. 695.
We would like to add citation #67 to the end of the sentence "...100% sensitive for detecting preinvasive disease."(67) A couple sentences later, we would like to replace citation #67 with citation #1 so it reads
"...gives a truer picture of the relative effect of different screening strategies on disease."(1)
Evelyn P.Whitlock, MD, MPH, Kimberly K. Vesco, MD, MPH, Jennifer S. Lin, MD, MCR, Michelle Eder, PhD, Brittany U. Burda, MPH
February 3, 2012
We thank Dr. Ronco and colleagues for pointing out our error in contrasting a higher cumulative cancer detection after co-testing in ARTISTIC with the opposite pattern in other co-testing trials. Fortunately, this error was only in the manuscript and not in our draft report the USPSTF used for its deliberations. The error was introduced when we omitted proportional cancer results from tables as we were editing to fit within space constraints for dissemination products, including the manuscript. This error has now been corrected to indicate that co-testing trials tended to find fewer cancers cumulatively than cytology and, where reported, after the second screening round (1).
In response to Dr. Ronco and colleagues' other points: We separated the different types of HPV-based primary screening due to their heterogeneity in approaches to screening and abnormal test management protocols (2;3). This is especially important since compliance with recommended followup procedures was incompletely reported, but available data indicate variability (4). Particularly without longer term follow-up, different screening strategies that result in differential opportunities for confirmatory testing with colposcopy, or that differ in compliance with recommended followup, may distort comparisons of screening sensitivity through asymmetry bias (5;6). Considering HPV-based primary screening strategies separately also facilitated indirect comparisons between different programmatic strategies; co-testing and primary HPV screening strategies differed little in benefit, with more potential harms with co-testing, which may be mitigated by adding a triage step (such as cytology) to primary HPV. However, we disagree with the assertion by Dr. Ronco and colleagues that colposcopy requirements for HPV with cytology triage will necessarily be similar to cytology alone. Recent reports from the FOCAL trial suggest they are 1.7-fold higher when the entire first screening round is considered (7). These increases may be offset by relative decreases in colposcopy requirements in the second round (not yet reported). Thus, we still believe that determining the net impact of HPV with cytology triage will not be possible until we have more complete results from important ongoing trials (8;9).
While we considered a hierarchy of potential outcomes, not just invasive cancers, no consensus exists on which outcomes are minimally sufficient to demonstrate a benefit over cytology screening in the absence of a clear impact on cervical cancer mortality or invasive cancer incidence. Demonstrated impacts on surrogates alone (e.g., reduced CIN3+ incidence) may require modeling to inform health policy changes (6). As such, while most co-testing evaluations within national screening programs in Europe found reduced incidence of CIN3+ in the second screening round (compared with cytology alone), relative CIN2+ detection was generally increased during the first round, and in some cases, cumulatively. An increased detection of CIN2+ cumulatively indicates a possible tradeoff between early disease detection and overdiagnosis (10), a serious concern in a disease with very low prevalence of progressive cancers (6).
Estimating both effectiveness and over-diagnosis requires longitudinal data from at least two screening rounds within a randomized trial (10). At the time of our report, complete data from two screening rounds was available from only two of four co-testing trials (NTCC Phase I, ARTISTIC) and one primary HPV screening trial (NTCC Phase II). Incident cervical cancer cases after co-testing were sparsely reported and represented complete follow-up for the entire study population in one study only (11). Since the publication of our report, complete second- round results from another trial (POBASCAM) suggest a similar pattern of reduced cancer incidence (12), although data on cancer stages were not reported. The benefit of earlier detection might be considered more robust with a demonstrated reduction in cancer 1B+ incidence (6).
Based on these new POBASCAM results, others have calculated that 3.2 additional CIN2/CIN3 would be treated to prevent 1 case of incident cancer as a means of estimating the potential over-treatment associated with cancer prevention (13). To address the programmatic impact, however, one might consider the incremental difference in cumulative cancers due to higher cross-sectional sensitivity with HPV-based screening compare to cytology alone. Under these considerations, 8 CIN2/CIN3 would be treated to prevent 1 cancer diagnosis. Neither of these calculations, however, considers potential increased harms other than those stemming from overtreatment (i.e. not harms related to unnecessary retesting, colposcopy, biopsies).
By design, our systematic review was limited to reporting available empirical data to directly quantify benefits and harms. The tradeoffs between earlier disease detection and overdiagnosis still cannot be well- quantified without more complete reporting from trials, unless supplemented by the addition of modeling exercises. To help further illuminate this issue, we highlighted the need for more complete reporting from available trials for all participants (complete second round screening and followup, perhaps with linkage to registries) and for a larger array of process measures and health outcomes (recommendations for and compliance with retesting for abnormal results, colposcopies, biopsies, and treatment, ideally with related harms). In doing so, we did not intend to suggest that randomized controlled trials are needed to evaluate every potential advance or nuance in cervical cancer screening, as we agree this would be inappropriate. Instead, comparative effectiveness evaluations to improve established cancer screening must rely on other evidence-based standards wherever appropriate (14).
Modeling allows comparisons of different rescreening intervals for different tests, different starting and stopping ages, and other approaches not tested in trials. Modeled results from the US suggest that a longer rescreening interval after co-testing (every five years) is required to achieve comparability with cytology in programmatic benefits and harms (15). These programmatic benefits, however, require adherence with prolonged intervals after co-testing to avoid expected harms from detecting transient HPV infections, among other issues (16). There is no national screening program in the US and evidence suggests prolonged screening intervals up to three years (or longer) are not standard after co-testing in individual or small-group practices (17). Thus, judgment is required as to how trial and modeling results for co-testing apply in the US outside of contexts such as the Veterans Administration, health maintenance organizations, or others managing stable populations over time. These judgments about applicability and other inferential activities are clearly the role of the USPSTF (18). Finally, we did not down-grade the quality of trials for issues such as participant blinding. Instead, we noted factors that could affect interpretation of results for these pragmatic trials, through mechanisms such as likelihood of seeking screening outside the program.
Yours sincerely, Evelyn P. Whitlock, MD, MPH Kimberly K. Vesco, MD, MPH Jennifer S. Lin, MD, MCR Michelle Eder, PhD Brittany U. Burda, MPH
(1) Whitlock EP, Vesco KK, Eder M, Lin JL, Senger CA, Burda BU. Correction: Liquid-based cytology and human papillomavirus screening for cervical cancer. Ann Intern Med 2012; 156(1):71-72.
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(3) Vesco KK, Whitlock EP, Eder M, Lin J, Burda BU, Senger CA et al. Screening for cervical cancer: a systematic evidence review for the US Preventive Services Task Force. Evidence Report No. 86. AHRQ Publication No. 11-05156-EF-1. 2011. Rockville, MD, Agency for Healthcare Research and Quality.
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(5) International Agency for Research on Cancer. IARC Handbooks of Cancer Prevention: Cervix Cancer Screening. Lyon, France: IARC Press; 2005.
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