Walter Kinney

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.

Cervical cancer risk for women undergoing concurrent testing for human papillomavirus and cervical cytology: a population-based study in routine clinical practice

BACKGROUND Concurrent testing for human papillomavirus (HPV) and cervical cytology (co-testing) is an approved alternative to cytology alone in women aged 30 years and older. We aimed to assess the safety in routine clinical practice of 3-year screening intervals for women testing negative for HPV with normal cytology and to assess if co-testing can identify women at high risk of cervical cancer or cervical intraepithelial neoplasia grade 3 (CIN3) or worse over 5 years. METHODS We assessed the 5-year cumulative incidence, starting in 2003-05, of cervical cancer and CIN3 or worse for 331,818 women aged 30 years and older who enrolled in co-testing at Kaiser Permanente Northern California (Berkeley, CA, USA) and had adequate enrolment co-test results. Follow-up continued until Dec 31, 2009. We defined cumulative incidence to include prevalence at enrolment and incidence after enrolment. Prevalence at enrolment was defined as the ratio of women diagnosed with each outcome on the biopsy visit immediately after their enrolment screening visit to the total enrolled women. At screening visits only HPV test and Pap smear samples were collected, and at biopsy visits colposcopically directed biopsies were taken. To estimate post-enrolment incidence, we used Weibull survival models. FINDINGS In 315,061 women negative by HPV testing, the 5-year cumulative incidence of cancer was 3.8 per 100,000 women per year, slightly higher than for the 306,969 who were both negative by HPV and Pap testing (3.2 per 100,000), and half the cancer risk of the 319,177 who were negative by Pap testing (7.5 per 100,000). 313,465 (99.5%) women negative by HPV testing had either normal cytology or equivocal abnormalities. Abnormal cytology greatly increased cumulative incidence of CIN3 or worse over 5 years for the 16,757 positive by HPV testing (12.1%vs 5.9%; p<0.0001). By contrast, although statistically significant, abnormal cytology did not increase 5-year risk of CIN3 or worse for women negative by HPV testing to a substantial level (0.86%vs 0.16%; p=0.004). 12,208 (73%) of the women positive by HPV testing had no cytological abnormality, and these women had 258 (35%) of 747 CIN3 or adenocarcinoma in situ, [corrected] 25 (29%) of 87 cancers, and 17 (63%) of 27 adenocarcinomas. INTERPRETATION For women aged 30 years and older in routine clinical practice who are negative by co-testing (both HPV and cytology), 3-year screening intervals were safe because a single negative test for HPV was sufficient to reassure against cervical cancer over 5 years. Incorporating HPV testing with cytology also resulted in earlier identification of women at high risk of cervical cancer, especially adenocarcinoma. Testing for HPV without adjunctive cytology might be sufficiently sensitive for primary screening for cervical cancer. FUNDING Intramural Research Program of the US National Cancer Institute/NIH/DHHS, and the American Cancer Society.

American Cancer Society Guideline for Human Papillomavirus (HPV) Vaccine Use to Prevent Cervical Cancer and Its Precursors

The American Cancer Society (ACS) has developed guidelines for the use of the prophylactic human papillomavirus (HPV) vaccine for the prevention of cervical intraepithelial neoplasia and cervical cancer. These recommendations are based on a formal review of the available evidence. They address the use of prophylactic HPV vaccines, including who should be vaccinated and at what age, as well as a summary of policy and implementation issues. Implications for screening are also discussed.

2012 updated consensus guidelines for the management of abnormal cervical cancer screening tests and cancer precursors.

ABSTRACT A group of 47 experts representing 23 professional societies, national and international health organizations, and federal agencies met in Bethesda, MD, September 14–15, 2012, to revise the 2006 American Society for Colposcopy and Cervical Pathology Consensus Guidelines. The group’s goal was to provide revised evidence-based consensus guidelines for managing women with abnormal cervical cancer screening tests, cervical intraepithelial neoplasia (CIN) and adenocarcinoma in situ (AIS) following adoption of cervical cancer screening guidelines incorporating longer screening intervals and co-testing. In addition to literature review, data from almost 1.4 million women in the Kaiser Permanente Northern California Medical Care Plan provided evidence on risk after abnormal tests. Where data were available, guidelines prescribed similar management for women with similar risks for CIN 3, AIS, and cancer. Most prior guidelines were reaffirmed. Examples of updates include: Human papillomavirus–negative atypical squamous cells of undetermined significance results are followed with co-testing at 3 years before return to routine screening and are not sufficient for exiting women from screening at age 65 years; women aged 21–24 years need less invasive management, especially for minor abnormalities; postcolposcopy management strategies incorporate co-testing; endocervical sampling reported as CIN 1 should be managed as CIN 1; unsatisfactory cytology should be repeated in most circumstances, even when HPV results from co-testing are known, while most cases of negative cytology with absent or insufficient endocervical cells or transformation zone component can be managed without intensive follow-up.

Where's the high-grade cervical neoplasia? The importance of minimally abnormal Papanicolaou diagnoses.

Objective To characterize the relative contributions of the different abnormal Papanicolaou smear cytologic diagnoses in the Bethesda System to the subsequent histologic diagnosis of high-grade cervical neoplasia. Methods A total of 46,009 nonpregnant female members of the Kaiser Permanente Health Plan, Northern California Region, were studied prospectively. The main outcome measures included routine Papanicolaou smear diagnoses and subsequent histologic diagnosis of colposcopically directed cervical tissue specimens. Results Atypical squamous cells of undetermined significance (ASCUS) was the most common abnormal Papanicolaou diagnosis, representing 3.6% of the total number of smears. Of the total number of cases of histologically confirmed high-grade cervical neoplasia present in the population, the largest proportion (38.8%) was in women with smears showing ASCUS. Minimal abnormalities combined (ASCUS, atypical glandular cells of undetermined significance, and low-grade squamous intraepithelial lesion) were coincident with 68.6% of the cases of histologic high-grade cervical neoplasia diagnosed in this routine screening population. Conclusion Recognition of the importance of equivocal and mild Papanicolaou test abnormalities in the subsequent diagnosis of high-grade cervical neoplasia emphasizes the need for accurate and cost-effective triage of the large population of women with minimally abnormal Papanicolaou diagnoses.

Use of primary high-risk human papillomavirus testing for cervical cancer screening: Interim clinical guidance

In 2011, the American Cancer Society, the American Society for Colposcopy and Cervical Pathology, and the American Society for Clinical Pathology updated screening guidelines for the early detection of cervical cancer and its precursors. Recommended screening strategies were cytology and cotesting (cytology in combination with hrHPV testing). These guidelines also addressed the use of hrHPV testing alone as a primary screening approach, which was not recommended for use at that time. There is now a growing body of evidence for screening with primary hrHPV testing, including a prospective US-based registration study. Thirteen experts including representatives from the Society of Gynecologic Oncology, American Society for Colposcopy and Cervical Pathology, American College of Obstetricians and Gynecologists, American Cancer Society, American Society of Cytopathology, College of American Pathologists, and the American Society for Clinical Pathology, convened to provide interim guidance for primary hrHPV screening. This guidance panel was specifically triggered by an application to the FDA for a currently marketed HPV test to be labeled for the additional indication of primary cervical cancer screening. Guidance was based on literature review and review of data from the FDA registration study, supplemented by expert opinion. This document aims to provide information for healthcare providers who are interested in primary hrHPV testing and an overview of the potential advantages and disadvantages of this strategy for screening as well as to highlight areas in need of further investigation.

Cervical Cancer Control, Priorities and New Directions

Cervical cancer is caused by infection with a range of high risk “oncogenic” human papillomavirus (HPV) types, and it is now accepted that >99% of cervical cancer is initiated by HPV infection. The estimated lifetime risk of cervical cancer is nevertheless relatively low (less than 1 in 20 for most community based studies). Although sensitivity and specificity of the available diagnostic techniques are suboptimal, screening for persistent HPV infection is effective in reducing the incidence of cervical cancer. Infection can be detected by molecular techniques or by cytological examination of exfoliated cervical cells. Persistent infection is the single best predictor of risk of cervical cancer. 1

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.

Five-Year Experience of Human Papillomavirus DNA and Papanicolaou Test Cotesting

OBJECTIVE: To estimate the 5-year age group–specific test positives for Pap tests and human papillomavirus (HPV) testing in a large, general screening population of women 30 and older. METHODS: Using data from Kaiser Permanente Northern California, a large health maintenance organization that introduced cotesting in 2003, we evaluated the cotesting results overall and by 5-year age groups. Women (n=580,289) who opted for and underwent cotesting (n cotests=812,598) between January 2003 and April 2008 were included in the analysis. Pap tests interpreted as atypical squamous cells of undetermined significance (ASC-US) or more severe were considered to be positive. Women were tested for carcinogenic HPV using an assay approved by the U.S. Food and Drug Administration. Binomial exact 95% confidence intervals (CIs) were calculated. RESULTS: Overall, 6.27% (95% CI 6.21–6.32%) of cotests were carcinogenic HPV positive, and only 3.99% (95% CI 3.94–4.03%) cotests had normal cytology and were carcinogenic HPV positive. By comparison, 5.18% (95% CI 5.13–5.23%) of cotests had ASC-US or more severe cytology, and 2.87% (95% CI 2.84–2.91%) of cotests had ASC-US or more severe cytology and were carcinogenic HPV negative. CONCLUSION: In a general screening population, concerns about excessive HPV test positives among women aged 30 years and older are not borne out. LEVEL OF EVIDENCE: III

Methylation of HPV18, HPV31, and HPV45 Genomes and Cervical Intraepithelial Neoplasia Grade 3

BACKGROUND Persistent infections with carcinogenic human papillomavirus (HPV) types are the necessary cause of cervical cancer. We recently demonstrated that the HPV16 genome is strongly methylated in cervical precancer compared with transient infections. However, the extent of methylation in other HPV types and its role in progression to cancer is poorly understood. METHODS We analyzed whole-genome methylation patterns of the three next most carcinogenic HPV genotypes: HPV31 (closely related to HPV16), and two other closely related types, HPV18 and HPV45. DNA was extracted from cervical cytology specimens from 92 women with precancer and 96 women infected with HPV31, HPV18, or HPV45, but who had no cytological or histological abnormalities. After bisulfite modification, genome-wide pyrosequencing was performed covering 80-106 sites. We calculated differences in median methylation, odds ratios, areas under the curve, and Spearman rank correlation coefficients for methylation levels between different sites. All statistical tests were two-sided. RESULTS For all three HPV types, we observed strongly elevated methylation levels at multiple CpG sites in the E2, L2, and L1 regions among women with cervical intraepithelial neoplasia grade 3 compared with women with transient infections. We observed high correlation of methylation patterns between phylogenetically related types. The highest areas under the curve were 0.81 for HPV31, 0.85 for HPV18, and 0.98 for HPV45. Differential methylation patterns in cervical intraepithelial neoplasia grade 3 patients with multiple infections suggest that methylation can clarify which of the infections is causal. CONCLUSIONS Carcinogenic HPV DNA methylation indicates transforming HPV infections. Our findings show that methylation of carcinogenic HPV types is a general phenomenon that warrants development of diagnostic assays.