Cervical Neoplasia Guidelines: United States and Europe Compared

Triage of HPV positive women in cervical cancer screening

Despite HPV vaccines, screening will remain central for decades to control cervical cancer. Recently, HPV testing alone or with cytology was introduced as an alternative to cytology screening. However, most HPV infections are harmless and additional tests are required to identify women with progressing infections or precancer. With three options for primary screening, and without clear strategies for triage of screen-positive women, there is great confusion about the best approach. Also, increasing HPV vaccination coverage will lead to lower disease prevalence, and force new screening approaches. Currently recommended triage strategies for primary HPV screening include HPV genotyping for HPV16 and HPV18 and cytology. Other alternatives that are currently evaluated include p16/Ki-67 dual stain cytology, host methylation, and viral methylation testing. Clinical management of women with cervical cancer screening results is moving to use risk thresholds rather than individual test results. Specific risk thresholds have been defined for return to primary screening, repeat testing, referral to colposcopy, and immediate treatment. Choice of test algorithms is based on comparison of absolute risk estimates from triage tests with established clinical thresholds. Importantly, triage tests need to be evaluated together with the primary screening test and the downstream clinical management. An optimal integrated screening and triage strategy should reassure the vast majority of women that they are at very low risk of cervical cancer, send the women at highest risk to colposcopy at the right time, when disease can be colposcopically detected, and minimize the intermediate risk group that requires continued surveillance.

Human papillomavirus testing versus repeat cytology for triage of minor cytological cervical lesions

BACKGROUND

Atypical squamous cells of undetermined significance (ASCUS) and low-grade squamous intra-epithelial lesions (LSIL) are minor lesions of the cervical epithelium, detectable by cytological examination of cells collected from the surface of the cervix of a woman.Usually, women with ASCUS and LSIL do not have cervical (pre-) cancer, however a substantial proportion of them do have underlying high-grade cervical intra-epithelial neoplasia (CIN, grade 2 or 3) and so are at increased risk for developing cervical cancer. Therefore, accurate triage of women with ASCUS or LSIL is required to identify those who need further management.This review evaluates two ways to triage women with ASCUS or LSIL: repeating the cytological test, and DNA testing for high-risk types of the human papillomavirus (hrHPV) - the main causal factor of cervical cancer.

OBJECTIVES

Main objective To compare the accuracy of hrHPV testing with the Hybrid Capture 2 (HC2) assay against that of repeat cytology for detection of underlying cervical intraepithelial neoplasia of grade 2 or worse (CIN2+) or grade 3 or worse (CIN3+) in women with ASCUS or LSIL. For the HC2 assay, a positive result was defined as proposed by the manufacturer. For repeat cytology, different cut-offs were used to define positivity: Atypical squamous cells of undetermined significance or worse (ASCUS+), low-grade squamous intra-epithelial lesions or worse (LSIL+) or high-grade squamous intra-epithelial lesions or worse (HSIL+).Secondary objective To assess the accuracy of the HC2 assay to detect CIN2+ or CIN3+ in women with ASCUS or LSIL in a larger group of reports of studies that applied hrHPV testing and the reference standard (coloscopy and biopsy), irrespective whether or not repeat cytology was done.

SEARCH METHODS

We made a comprehensive literature search that included the Cochrane Register of Diagnostic Test Accuracy Studies; the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library), MEDLINE (through PubMed), and EMBASE (last search 6 January 2011). Selected journals likely to contain relevant papers were handsearched from 1992 to 2010 (December). We also searched CERVIX, the bibliographic database of the Unit of Cancer Epidemiology at the Scientific Institute of Public Health (Brussels, Belgium) which contains more than 20,000 references on cervical cancer.More recent searches, up to December 2012, targeted reports on the accuracy of triage of ASCUS or LSIL with other HPV DNA assays, or HPV RNA assays and other molecular markers. These searches will be used for new Cochrane reviews as well as for updates of the current review.

SELECTION CRITERIA

Studies eligible for inclusion in the review had to include: women presenting with a cervical cytology result of ASCUS or LSIL, who had undergone both HC2 testing and repeat cytology, or HC2 testing alone, and were subsequently subjected to reference standard verification with colposcopy and colposcopy-directed biopsies for histologic verification.

DATA COLLECTION AND ANALYSIS

The review authors independently extracted data from the selected studies, and obtained additional data from report authors.Two groups of meta-analyses were performed: group I concerned triage of women with ASCUS, group II concerned women with LSIL. The bivariate model (METADAS-macro in SAS) was used to assess the absolute accuracy of the triage tests in both groups as well as the differences in accuracy between the triage tests.

MAIN RESULTS

The pooled sensitivity of HC2 was significantly higher than that of repeat cytology at cut-off ASCUS+ to detect CIN2+ in both triage of ASCUS and LSIL (relative sensitivity of 1.27 (95% CI 1.16 to 1.39; P value < 0.0001) and 1.23 (95% CI 1.06 to 1.4; P value 0.007), respectively. In ASCUS triage, the pooled specificity of the triage methods did not differ significantly from each other (relative specificity: 0.99 (95% CI 0.97 to 1.03; P value 0.98)). However, the specificity of HC2 was substantially, and significantly, lower than that of repeat cytology in the triage of LSIL (relative specificity: 0.66 (95% CI 0.58 to 0.75) P value < 0.0001).

AUTHORS' CONCLUSIONS

HPV-triage with HC2 can be recommended to triage women with ASCUS because it has higher accuracy (significantly higher sensitivity, and similar specificity) than repeat cytology. When triaging women with LSIL, an HC2 test yields a significantly higher sensitivity, but a significantly lower specificity, compared to a repeat cytology. Therefore, practice recommendations for management of women with LSIL should be balanced, taking local circumstances into account.

The APTIMA HPV assay versus the Hybrid Capture 2 test in triage of women with ASC-US or LSIL cervical cytology: a meta-analysis of the diagnostic accuracy

Testing for DNA of 13 high-risk HPV types with the Hybrid Capture 2 (HC2) test has consistently been shown to perform better in triage of women with cervical cytology results showing atypical squamous cells of undetermined significance (ASC-US) but often not in triage of low-grade squamous intraepithelial lesions (LSIL) detected in cervical cancer screening. In a meta-analysis, we compared the accuracy of the APTIMA HPV test, which identifies RNA of 14 high-risk HPV types, to HC2 for the triage of women with ASC-US or LSIL. Literature search-targeted studies where the accuracy of APTIMA HPV and HC2 for detection of underlying CIN2/3+ was assessed concomitantly including verification of all cases of ASC-US and LSIL. HSROC (Hierarchical Summary ROC) curve regression was used to compute the pooled absolute and relative sensitivity and specificity. Eight studies, comprising 1,839 ASC-US and 1,887 LSIL cases, were retrieved. The pooled sensitivity and specificity of APTIMA to triage ASC-US to detect underlying CIN3 or worse was 96.2% (95% CI = 91.7-98.3%) and 54.9% (95% CI = 43.5-65.9%), respectively. APTIMA and HC2 showed similar pooled sensitivity; however, the specificity of the former was significantly higher (ratio: 1.19; 95% CI = 1.08-1.31 for CIN2+). The pooled sensitivity and specificity of APTIMA to triage LSIL were 96.7% (95% CI = 91.4-98.9%) and 38.7% (95% CI = 30.5-47.6%) for CIN3+. APTIMA was as sensitive as HC2 but more specific (ratio: 1.35; 95% CI = 1.11-1.66). Results were similar for detection of CIN2 or worse. In both triage of ASC-US and LSIL, APTIMA is as sensitive but more specific than HC2 for detecting cervical precancer.

Cervical screening strategies in resourced and resource-constrained countries

Screening for cervical cancer is well established in resourced countries, but in resource-constrained countries, it is almost non-existent at national level. In resourced countries, the Pap test forms the hallmark of screening, with the human papillomavirus DNA test a recent adjunct. In many resourced countries, however, screening for cervical cancer is still far from ideal. A coverage around 50% prevails in some countries, and few have reached the target of 80% or more. Furthermore, the human papillomavirus test and newly developed biomarkers may lead to the development of a 'super test', which could be applied less frequently compared with present-day cytological screening. In resource-constrained countries, the movement is towards a 'screen and treat' approach. The main screening methods under investigation are the visual inspection after diluted acetic acid application test and the human papillomavirus test. Cryotherapy and large loop excision of the transformation zone have been used most often as treatment methods. The ideal seems to be the human papillomavirus test with large loop excision of the transformation zone, provided a low-cost human papillomavirus test becomes available. Coverage is even a greater problem in resource-constrained countries, a problem in need of urgent attention. Resource-constrained countries, however, must curtail the high incidence of cervical cancer, which is often a lower priority than other pressing healthcare needs.