Julia C. Gage

Human Papillomavirus Testing in the Prevention of Cervical Cancer

Strong evidence now supports the adoption of cervical cancer prevention strategies that explicitly focus on persistent infection with the causal agent, human papillomavirus (HPV). To inform an evidence-based transition to a new public health approach for cervical cancer screening, we summarize the natural history and cervical carcinogenicity of HPV and discuss the promise and uncertainties of currently available screening methods. New HPV infections acquired at any age are virtually always benign, but persistent infections with one of approximately 12 carcinogenic HPV types explain virtually all cases of cervical cancer. In the absence of an overtly persistent HPV infection, the risk of cervical cancer is extremely low. Thus, HPV test results predict the risk of cervical cancer and its precursors (cervical intraepithelial neoplasia grade 3) better and longer than cytological or colposcopic abnormalities, which are signs of HPV infection. The logical and inevitable move to HPV-based cervical cancer prevention strategies will require longer screening intervals that will disrupt current gynecologic and cytology laboratory practices built on frequent screening. A major challenge will be implementing programs that do not overtreat HPV-positive women who do not have obvious long-term persistence of HPV or treatable lesions at the time of initial evaluation. The greatest potential for reduction in cervical cancer rates from HPV screening is in low-resource regions that can implement infrequent rounds of low-cost HPV testing and treatment.

Number of cervical biopsies and sensitivity of colposcopy.

OBJECTIVE: To examine the influence that type of medical training and number of biopsies have on sensitivity of colposcopically guided biopsies. METHODS: Among 408 women with an adequate enrollment colposcopy and a diagnosis of cervical intraepithelial neoplasia (CIN) 3 or cancer (CIN 3+) over 2 years in the Atypical Squamous Cells of Undetermined Significance/Low-Grade Squamous Intraepithelial Lesions (ASCUS-LSIL) Triage Study, we evaluated factors influencing the sensitivity of the enrollment colposcopic procedure. We used contingency table analysis to examine confounding variables and &khgr;2 tests to ascertain statistical significance. RESULTS: Overall, 69.9% of women with a cumulative diagnosis of CIN 3+ had a “true-positive” enrollment colposcopically guided biopsy result of CIN 2 or worse (CIN 2+), the threshold that would trigger excisional therapy. The sensitivity of the procedure did not vary significantly by type of colposcopist. However, the sensitivity was significantly greater when the colposcopists took two or more biopsies instead of one (P<.01), a pattern observed across all types of colposcopists. Independent of the severity of the colposcopic impression, the frequency with which colposcopists took two or more biopsies instead of one varied (in descending order) from nurse practitioners to general gynecologists to gynecologic oncology fellows to gynecologic oncologists (P<.01). CONCLUSION: Colposcopy with guided biopsy or biopsies detects approximately two thirds of CIN 3+. Although the sensitivity of the procedure does not differ significantly by type of medical training, it is greater when two or more biopsies are taken. LEVEL OF EVIDENCE: II-2

Benchmarking CIN 3+ risk as the basis for incorporating HPV and Pap cotesting into cervical screening and management guidelines.

Objective In 2012, the US Preventive Services Task Force (USPSTF) and a consensus of 25 organizations endorsed concurrent cytology and human papillomavirus (HPV) testing (“cotesting”) for cervical cancer screening. Past screening and management guidelines were implicitly based on risks defined by Pap-alone, without consideration of HPV test results. To promote management that is consistent with accepted practice, new guidelines incorporating cotesting should aim to achieve equal management of women at equal risk of cervical intraepithelial neoplasia grade 3 and cancer (CIN 3+). Methods We estimated cumulative 5-year risks of CIN 3+ for 965,360 women aged 30 to 64 years undergoing cotesting at Kaiser Permanente Northern California over 2003 to 2010. We calculated the implicit risk thresholds for Pap-alone and applied them for new management guidance on HPV and Pap cotesting, citing 2 examples: HPV-positive/atypical squamous cells of undetermined significance (ASC-US) and HPV-negative/Pap-negative. We call this guidance process “benchmarking.” Results A low-grade squamous intraepithelial lesion result, for which immediate colposcopy is prescribed, carries a 5-year CIN 3+ risk of 5.2%, suggesting that test results with similar risks should be managed with colposcopy. Similarly, ASC-US (2.6% risk) is managed with a 6- to 12-month follow-up visit and Pap-negative (0.26% risk) is managed with a 3-year follow-up visit. The 5-year CIN 3+ risk among women with HPV-positive/ASC-US was 6.8% (95% confidence interval = 6.2%–7.6%). This is greater than the 5.2% risk implicitly leading to referral for colposcopy, consistent with current management recommendations that women with HPV-positive/ASC-US be referred for immediate colposcopy. The 5-year CIN 3+ risk among women with HPV-negative/Pap-negative results was 0.08% (95% confidence interval = 0.07%–0.09%), far below the 0.26% implicitly required for a 3-year return and justifying a longer (e.g., 5-year) return. Conclusions Using the principle of “equal management of equal risks,” benchmarking to implicit risk thresholds based on Pap-alone can be used to achieve safe and consistent incorporation of cotesting.

The accuracy of colposcopic grading for detection of high-grade cervical intraepithelial neoplasia

Objective. To relate aspects of online colposcopic image assessment to the diagnosis of grades 2 and 3 cervical intraepithelial neoplasia (CIN 2+). Methods: To simulate colposcopic assessment, we obtained digitized cervical images at enrollment after acetic acid application from 919 women referred for equivocal or minor cytologic abnormalities into the ASCUS-LSIL Triage Study. For each, 2 randomly assigned evaluators from a pool of 20 colposcopists assessed images using a standardized tool online. We calculated the accuracy of these assessments for predicting histologic CIN 2+ over the 2 years of study. For validation, a subset of online results was compared with same-day enrollment colposcopic assessments. Results. Identifying any acetowhite lesion in images yielded high sensitivity: 93% of women with CIN 2+ had at least 1 acetowhite lesion. However, 74% of women without CIN 2+ also had acetowhitening, regardless of human papillomavirus status. The sensitivity for CIN 2+ of an online colpophotographic assessment of high-grade disease was 39%. The sensitivity for CIN 2+ of a high-grade diagnosis by Reid Index scoring was 30%, and individual Reid Index component scores had similar levels of sensitivity and specificity. The performance of online assessment was not meaningfully different from that of same-day enrollment colposcopy, suggesting that these approaches have similar utility. Conclusions. Finding acetowhite lesions identifies women with CIN 2+, but using subtler colposcopic characteristics to grade lesions is insensitive. All acetowhite lesions should be assessed with biopsy to maximize sensitivity of colposcopic diagnosis with good specificity.

Clinical Human Papillomavirus Detection Forecasts Cervical Cancer Risk in Women Over 18 Years of Follow-Up

PURPOSE To describe the long-term (≥ 10 years) benefits of clinical human papillomavirus (HPV) DNA testing for cervical precancer and cancer risk prediction. METHODS Cervicovaginal lavages collected from 19,512 women attending a health maintenance program were retrospectively tested for HPV using a clinical test. HPV positives were tested for HPV16 and HPV18 individually using a research test. A Papanicolaou (Pap) result classified as atypical squamous cells of undetermined significance (ASC-US) or more severe was considered abnormal. Women underwent follow-up prospectively with routine annual Pap testing up to 18 years. Cumulative incidence rates (CIRs) of ≥ grade 3 cervical intraepithelial neoplasia (CIN3+) or cancer for enrollment test results were calculated. RESULTS A baseline negative HPV test provided greater reassurance against CIN3+ over the 18-year follow-up than a normal Pap (CIR, 0.90% v 1.27%). Although both baseline Pap and HPV tests predicted who would develop CIN3+ within the first 2 years of follow-up, only HPV testing predicted who would develop CIN3+ 10 to 18 years later (P = .004). HPV16- and HPV18-positive women with normal Pap were at elevated risk of CIN3+ compared with other HPV-positive women with normal Pap and were at similar risk of CIN3+ compared with women with a low-grade squamous intraepithelial Pap. CONCLUSION HPV testing to rule out cervical disease followed by Pap testing and possibly combined with the detection of HPV16 and HPV18 among HPV positives to identify those at immediate risk of CIN3+ would be an efficient algorithm for cervical cancer screening, especially in women age 30 years or older.

Five-year risks of CIN 3+ and cervical cancer among women who test Pap-negative but are HPV-positive.

Objective Current US guidelines for cotesting recommend that the large numbers of women who test Pap-negative, but human papillomavirus (HPV)–positive, return in 1 year, and those who remain HPV-positive or have low-grade squamous intraepithelial lesion (LSIL) or worse Pap results be referred for colposcopy. However, the performance of these guidelines in routine clinical practice has not been evaluated. Methods We estimated cumulative 5-year risks of cervical intraepithelial neoplasia grade 3 or worse (CIN 3+) among 32,374 women aged 30 to 64 years with HPV-positive/Pap-negative cotest results at Kaiser Permanente Northern California during 2003 to 2010. Results The 5-year CIN 3+ risk after an HPV-positive/Pap-negative cotest result, which was found in 3.6% of women, was 4.5% (95% confidence interval [CI] = 4.2%–4.8%). The 5-year cancer risk was 0.34% (95% CI = 0.26%–0.45%), and half of the cases were adenocarcinoma. Overall, 48% of the women remained HPV-positive on return (median = 418 days after baseline), a percentage that varied little over ages 30 to 64 years. At the return after a baseline HPV-positive/Pap-negative result, almost every repeat cotest result predicted greater subsequent 5-year CIN 3+ risk than the same cotest result had at baseline (HPV-positive/LSIL, 9.2% vs 6.1%, p = .01; HPV-positive/atypical squamous cells of undetermined significance [ASC-US], 7.9% vs 6.8%, p = .2; HPV-positive/Pap-negative, 7.4% vs 4.5%, p < .0001; HPV-negative/LSIL,1.7% vs 2.0%, p = .8; HPV-negative/ASC-US, 2.9% vs 0.43%, p = .0005; HPV-negative/Pap-negative, 0.93% vs 0.08%, p < .0001). Conclusions Using the principle of “equal management of equal risks,” women testing HPV-positive/Pap-negative had a subsequent CIN 3+ risk consistent with risk thresholds for a 1-year return. However, on returning in approximately 1 year, about one-half of women will be referred for colposcopy because of continued HPV positivity or Pap abnormality. Clinicians should keep in mind that cotest results at the return after a baseline HPV-positive/Pap-negative finding are riskier than the same baseline cotest results in the general population, supporting intensified clinical management at return testing.

Detection of Precancerous Cervical Lesions Is Differential by Human Papillomavirus Type

Epidemiologic studies have reported the underrepresentation of cervical precancerous lesions caused by human papillomavirus (HPV) types 18 and 45 (HPV18/45) compared with the proportion of cervical cancers attributed to these HPV types. We investigated the timing of diagnosis of histologic cervical intraepithelial neoplasia grade 3 or worse (CIN3+) using data from the atypical squamous cells of undetermined significance-low-grade squamous intraepithelial lesion triage study (ALTS). Of the 2,725 women who underwent enrollment colposcopy, 412 of 472 (87.3%) diagnosed with histologic CIN3+ over the 2-year duration of ALTS could be assigned to a HPV type or group of types and were included in this analysis. Eighty-four percent of HPV16-positive CIN3+ were diagnosed at enrollment, compared with 57% of HPV18/45-positive CIN3+, and 58% of CIN3 positive for other carcinogenic HPV types at enrollment. In contrast, only 8% of HPV16-positive CIN3+ were diagnosed at exit, whereas 31% were HPV18/45 positive and 22% were positive for other carcinogenic types at study exit (P < 0.001). These results indicate the underrepresentation of HPV18/45 in precancers, whereas HPV16-associated CIN3+ is diagnosed much earlier. Whether the underrepresentation of 18/45 may be due to occult pathology needs further investigation.

Five-year risks of CIN 3+ and cervical cancer among women with HPV testing of ASC-US Pap results.

Objective New screening guidelines recommend that human papillomavirus (HPV)–negative/atypical squamous cells of undetermined significance (ASC-US) results be considered as equivalent to HPV-negative/Pap-negative results, leading to rescreening in 5 years. However, despite ample data, the routine clinical performance of HPV testing of women with ASC-US has not been adequately documented. Methods We estimated 5-year risks of cervical intraepithelial neoplasia (CIN) 3+ and of cancer among 2 groups of women between 2003 and 2010 at Kaiser Permanente Northern California: 27,050 aged 30 to 64 years who underwent HPV and Pap cotesting and had an ASC-US Pap result and 12,209 aged 25 to 29 years who underwent HPV triage of ASC-US. Results Five-year risks of CIN 3+ and of cancer among women aged 30 to 64 years testing HPV-negative/ASC-US and among 923,152 women testing Pap-negative alone were similar although statistically distinguishable (CIN 3+, 0.43% vs 0.26%, p = .001; cancer, 0.050% vs 0.025%, p = .1). The increased risk of cancer after HPV-negative/ASC-US versus Pap-negative alone was confined to women aged 60 to 64 years (0.26% vs 0.035%, p = .3). Five-year risks of CIN 3+ and cancer among women with HPV-negative/ASC-US results were substantially higher than those among women testing HPV-negative/Pap-negative (CIN 3+, 0.43% vs 0.08%, p < .0001; cancer, 0.050% vs 0.011%, p = .003). For women aged 30 to 64 years testing HPV-positive/ASC-US, 5-year risks of CIN 3+ and cancer were slightly higher than those among 9,374 women with low-grade squamous intraepithelial lesion (LSIL) (CIN 3+, 6.8% vs 5.2%, p = .0007; cancer, 0.41% vs 0.16%, p = .04). Similar patterns were seen for women aged 25 to 29 years. Conclusions Women with HPV-negative/ASC-US had a similar risk as women testing Pap-negative alone but had a higher risk than women testing HPV-negative/Pap-negative. Based upon the principle of “equal management of equal risks,” our findings support the equal management of women with HPV-negative/ASC-US and those with Pap-negative alone, except for exiting women from screening because cancer risks at ages 60 to 64 years may be higher for women testing HPV-negative/ASC-US. Our findings also support managing HPV-positive/ASC-US and LSIL similarly.

Human Papillomavirus Genotype Attribution and Estimation of Preventable Fraction of Anal Intraepithelial Neoplasia Cases Among HIV-Infected Men Who Have Sex With Men

BACKGROUND The prevention of human papillomavirus (HPV)-induced anal cancer in high-risk populations such as human immunodeficiency virus (HIV)-infected men who have sex with men (MSM) remains an urgent priority, given rising incidence rates despite widespread antiretroviral therapy use. METHODS HPV genotypes and anal disease prevalence, by cytology and histopathologic findings, were evaluated among 363 HIV-infected MSM. We modeled fractions of high-grade anal intraepithelial neoplasia (HGAIN) attributable to individual carcinogenic HPV genotypes and estimated the range of the proportion of HGAIN cases potentially preventable by prophylactic HPV vaccines. RESULTS HPV16 was the most common genotype overall (26.4% of cases) and among HGAIN cases (55%). Prevalence of multiple (≥ 2) carcinogenic HPV genotypes increased from 30.9% in cases of AIN grade <1 to 76.3% in cases of AIN grade 3 (P(trend) < .001). The fractions of HGAIN cases attributable to carcinogenic HPV16/18 targeted by currently licensed bivalent and quadrivalent HPV vaccines ranged from 12% to 61.5%, and the fractions attributable to carcinogenic HPV16/18/31/33/45/52/58 targeted by an investigational nonavalent HPV vaccine ranged from 39% to 89.4%. CONCLUSIONS Our analytical framework allows estimation of HGAIN cases attributable to individual HPV genotypes in the context of multiple concurrent HPV infections, which are very common among HIV-infected MSM. Our results suggest that licensed and investigational HPV prophylactic vaccines have the potential to prevent a substantial proportion of HGAIN cases in this population.

A Study of Genotyping for Management of Human Papillomavirus-Positive, Cytology-Negative Cervical Screening Results

ABSTRACT The effective management of women with human papillomavirus (HPV)-positive, cytology-negative results is critical to the introduction of HPV testing into cervical screening. HPV typing has been recommended for colposcopy triage, but it is not clear which combinations of high-risk HPV types provide clinically useful information. This study included 18,810 women with Hybrid Capture 2 (HC2)-positive, cytology-negative results and who were age ≥30 years from Kaiser Permanente Northern California. The median follow-up was 475 days (interquartile range [IQR], 0 to 1,077 days; maximum, 2,217 days). The baseline specimens from 482 cases of cervical intraepithelial neoplasia grade 3 or cancer (CIN3+) and 3,517 random HC2-positive noncases were genotyped using 2 PCR-based methods. Using the case-control sampling fractions, the 3-year cumulative risks of CIN3+ were calculated for each individual high-risk HPV type. The 3-year cumulative risk of CIN3+ among all women with HC2-positive, cytology-negative results was 4.6%. HPV16 status conferred the greatest type-specific risk stratification; women with HC2-positive/HPV16-positive results had a 10.6% risk of CIN3+, while women with HC-2 positive/HPV16-negative results had a much lower risk of 2.4%. The next most informative HPV types and their risks in HPV-positive women were HPV33 (5.9%) and HPV18 (5.9%). With regard to the etiologic fraction, 20 of 71 cases of cervical adenocarcinoma in situ (AIS) and adenocarcinoma in the cohort were positive for HPV18. HPV16 genotyping provides risk stratification useful for guiding clinical management; the risk among HPV16-positive women clearly exceeds the U.S. consensus risk threshold for immediate colposcopy referral. HPV18 is of particular interest because of its association with difficult-to-detect glandular lesions. There is a less clear clinical value of distinguishing the other high-risk HPV types.