Study protocol

As previously described, the ATHENA HPV study enrolled more than 47,000 women aged 21 years and older who presented for cervical cancer screening; all eligible participants had both Papanicolaou testing (by liquid-based cytology, ThinPrep; Hologic, Bedford, MA) and HPV testing (by Amplicor HPV test, Linear Array high-risk HPV genotyping test, and the cobas HPV Test, all from Roche Molecular Systems). The protocol was approved by the institutional review boards at all study sites, and all women provided written informed consent before undergoing any study procedures. The current analysis focuses only on the subset of women aged 30 years old and older to compare alternative management strategies with those endorsed in the current guidelines.

All women in this subset who had either abnormal cytology (atypical squamous cells of undetermined significance [ASC-US] or greater) or who tested positive for HPV (by Amplicor or Linear Array test) were scheduled for colposcopy. In addition, to adjust for ascertainment bias, a randomly selected subset of women who tested negative for both cytology and HPV had colposcopy. Colposcopic biopsies were performed according to a standardized protocol, and a random biopsy was required in all women with adequate colposcopy in whom no lesion was seen; patients and colposcopists were blinded to the cytology and HPV results.

An expert central pathology review (CPR) panel of 3 pathologists read all biopsies masked to any clinical data. Women achieving the study endpoint of CIN2 or more severe by CPR exited the study; those who did not reach this endpoint proceeded to the 3 year follow-up phase of the study, scheduled to conclude December 2012. The current analysis is restricted to disease detected at enrollment; disease detected over the subsequent 3 years of follow-up will be analyzed separately.

Screening strategies

The 10 screening strategies were evaluated based on review of the published cervical cancer screening literature and appear to be the strategies most likely to be considered potentially attractive by the clinical and public health communities. Strategies 1 and 2 are cytology screening strategies ( Figure 1 ). Strategy 1 consists of screening with cytology with reflex HPV testing (pooled high-risk HPV test for 14 genotypes) of ASC-US and referral of all women with HPV-positive ASC-US or low-grade squamous intraepithelial lesion (LSIL) or greater to colposcopy. Because this is the strategy most widely used in the United States, it serves as the comparator for the other 9 strategies.

Cytology primary screening options

Strategies 1 and 2 screened initially with cytology only. Strategy 1, a recommended screening option for women aged 21 years or older, triages ASC-US by reflex HPV testing, sending to colposcopy ASC-US/HPV positive and more severe than ASC-US (ie, ASC with possible HSIL [ASC-H], LSIL, atypical glandular cells [AGC], and HSIL). Women with normal cytology or ASC-US/HPV negativity continued with routine screening. Strategy 2 sent all women with any abnormal cytology (ie, ASC-US or more severe) to colposcopy, and all women with normal cytology continued with routine screening. This is not a recommended screening option but is included in this study for comparison with other options.

ASC-US, atypical squamous cells of undetermined significance; HPV, human papillomavirus; HSIL, high-grade squamous intraepithelial lesion; LSIL, low-grade squamous intraepithelial lesion.

Cox. Cervical cancer screening strategies: evaluation of results from the ATHENA HPV study. Am J Obstet Gynecol 2013.

Strategy 2 consists of screening with cytology alone, with referral of all women with ASC-US or greater to colposcopy. Strategies 3, 4, and 5 ( Figure 2 ) incorporate cotesting with both cytology and HPV testing. They vary as to whether genotyping for HPV 16 and HPV 18 is used and by the cytological threshold for referral to colposcopy. Strategies 6 through 10 ( Figure 3 ) use HPV testing alone (pooled high-risk HPV test with, or without, genotyping for HPV 16/18) as the initial screening test and differ by which triage tests are used to evaluate HPV-positive women. In the strategies described, women who did not meet the criteria for either immediate colposcopy or return to routine screening would be deferred to a 1 year follow-up per the current guidelines as indicated in Figures 2 and 3 .

Cotesting primary screening options

Strategies 3-5 screened initially with both cytology and testing for high-risk HPV. Strategies 4 and 5 also utilized the information provided when the HPV test also included separate results for HPV 16 and HPV 18 genotyping or, if not, when reflex genotyping could be done. Strategy 3, 1 of 2 recommended cotesting options for women aged 30 years or older, referred to colposcopy women with ASC-US HPV positivity and LSIL or more severe, irrespective of HPV result, whereas women with cytology-negativity/HPV positivity had repeat cotesting in 12 months and women who were cytology negative/HPV negative and ASC-US/HPV negative continued routine screening. Strategy 4, also a recommended cotesting strategy, referred to colposcopy women who were ASC-US/HPV positive and LSIL or more severe irrespective of HPV result, as well as all women who were cytology negative/HPV 16/HPV 18 positive. Women who were cytology negative/HPV positive but not positive for HPV 16 or HPV 18 had repeat cotesting in 12 months, and women who were cytology negative/HPV negative and ASC-US/HPV negative continued with routine screening. Strategy 5 was similar to strategy 4 except that the threshold for referral to colposcopy was LSIL or more severe or cytology negative/HPV 16/HPV 18 positive or ASC-US/HPV 16/HPV 18 positive, whereas ASC-US or negative cytology/HPV positive but not HPV 16/HPV 18 positive had 12 month follow-up.

ASC-US, atypical squamous cells of undetermined significance; HPV, human papillomavirus; LSIL, low-grade squamous intraepithelial lesion.

Cox. Cervical cancer screening strategies: evaluation of results from the ATHENA HPV study. Am J Obstet Gynecol 2013.

HPV screening algorithms

Strategies 6-10 screened initially with HPV testing. Strategy 6 referred all HPV-positive women to colposcopy and all HPV-negative women to routine screening. Strategy 7 reflex tested all HPV-positive women with cytology, referring to colposcopy only those with ASC-US or more severe, whereas those with negative cytology had follow-up in 12 months. Strategy 8 screened initially with a panel of HPV plus genotyping for HPV 16 and HPV 18, referring to colposcopy all women testing positive for HPV 16 and/or HPV 18 and to 12 month follow-up women positive for other HPV genotypes but not positive for HPV 16/HPV 18. Strategy 9 screened initially with a panel of HPV plus genotyping for HPV 16 and HPV 18, referring all women who were HPV 16/HPV 18 positive to colposcopy and reflex testing by cytology those HPV positive but not positive for HPV 16/HPV 18. Women with any abnormal cytology ASC-US or more severe were also referred to colposcopy, whereas women who were cytology negative/HPV positive for non–HPV 16/HPV 18 had 12 month follow-up. Strategy 10 screened initially with a panel of HPV plus genotyping for HPV 16 and HPV 18, referring all women who were HPV 16/HPV 18 positive to colposcopy and reflex testing by cytology those HPV positive but not positive for HPV 16/HPV 18. Women with LSIL or more severe were also referred to colposcopy, whereas women who were cytology negative/HPV positive and ASC-US/HPV positive for non–HPV 16/HPV 18 had 12 month follow-up.

ASC-US, atypical squamous cells of undetermined significance; HPV, human papillomavirus.

Cox. Cervical cancer screening strategies: evaluation of results from the ATHENA HPV study. Am J Obstet Gynecol 2013.

Statistical analysis

For each screening strategy, the number of tests (cytology and/or HPV test with or without integrated HPV 16/18 genotype detection) required at baseline was calculated, as was the number of colposcopies required to detect 1 case of CIN2 or more severe or CIN3 or more severe. From the total catchment of CIN2 or more severe and CIN3 or more severe detected, the number of cases not identified at baseline, and an estimate of the number that could potentially be identified by each strategy at 12 month follow-up were calculated. The crude sensitivity and specificity for detection of CIN2 or more severe or CIN3 or more severe and its sensitivity and specificity relative to strategy 1 were also determined ( Tables 2 and 3 ).

The cobas HPV Test results were categorized as follows: HPV positive (positive for any of 14 high-risk HPV types); HPV negative (negative for all 14 high-risk HPV types); HPV 16/18 positive (positive for HPV 16 and/or HPV 18, regardless of the presence or absence of 12 other HPV types); positive for 12 other HPV types (positive for 1 or more of the 12 other HPV types and negative for HPV 16 and HPV 18).

For calculations of sensitivity and specificity, only those cases in which colposcopy was performed and a valid biopsy result was obtained were considered. Crude estimates are given because the intent was to report on the utility of the strategies as would be observed in a clinical situation. Verification bias adjustment would not change the relative sensitivities or specificities of the various strategies or represent what happens in clinical practice.