Clare Gilham

The cervical cancer epidemic that screening has prevented in the UK

BACKGROUNDnRecent reports suggest that the reduction in mortality achieved by the UK national cervical screening programme is too small to justify its financial and psychosocial costs, except perhaps in a few high-risk women.nnnMETHODSnWe analysed trends in mortality before 1988, when the British national screening programme was launched, to estimate what future trends in cervical cancer mortality would have been without any screening.nnnFINDINGSnCervical cancer mortality in England and Wales in women younger than 35 years rose three-fold from 1967 to 1987. By 1988, incidence in this age-range was among the highest in the world despite substantial opportunistic screening. Since national screening was started in 1988, this rising trend has been reversed.nnnINTERPRETATIONnCervical screening has prevented an epidemic that would have killed about one in 65 of all British women born since 1950 and culminated in about 6000 deaths per year in this country. However, these estimates are subject to substantial uncertainty, particularly in relation to the effects of oral contraceptives and changes in sexual behaviour. 80% or more of these deaths (up to 5000 deaths per year) are likely to be prevented by screening, which means that about 100000 (one in 80) of the 8 million British women born between 1951 and 1970 will be saved from premature death by the cervical screening programme at a cost per life saved of about pound 36000. The birth cohort trends also provide strong evidence that the death rate throughout life is substantially lower in women who were first screened when they were younger.

Efficacy of HPV-based screening for prevention of invasive cervical cancer: follow-up of four European randomised controlled trials

BACKGROUNDnIn four randomised trials, human papillomavirus (HPV)-based screening for cervical cancer was compared with cytology-based cervical screening, and precursors of cancer were the endpoint in every trial. However, direct estimates are missing of the relative efficacy of HPV-based versus cytology-based screening for prevention of invasive cancer in women who undergo regular screening, of modifiers (eg, age) of this relative efficacy, and of the duration of protection. We did a follow-up study of the four randomised trials to investigate these outcomes.nnnMETHODSn176,464 women aged 20-64 years were randomly assigned to HPV-based (experimental arm) or cytology-based (control arm) screening in Sweden (Swedescreen), the Netherlands (POBASCAM), England (ARTISTIC), and Italy (NTCC). We followed up these women for a median of 6·5 years (1,214,415 person-years) and identified 107 invasive cervical carcinomas by linkage with screening, pathology, and cancer registries, by masked review of histological specimens, or from reports. Cumulative and study-adjusted rate ratios (experimental vs control) were calculated for incidence of invasive cervical carcinoma.nnnFINDINGSnThe rate ratio for invasive cervical carcinoma among all women from recruitment to end of follow-up was 0·60 (95% CI 0·40-0·89), with no heterogeneity between studies (p=0·52). Detection of invasive cervical carcinoma was similar between screening methods during the first 2·5 years of follow-up (0·79, 0·46-1·36) but was significantly lower in the experimental arm thereafter (0·45, 0·25-0·81). In women with a negative screening test at entry, the rate ratio was 0·30 (0·15-0·60). The cumulative incidence of invasive cervical carcinoma in women with negative entry tests was 4·6 per 10(5) (1·1-12·1) and 8·7 per 10(5) (3·3-18·6) at 3·5 and 5·5 years, respectively, in the experimental arm, and 15·4 per 10(5) (7·9-27·0) and 36·0 per 10(5) (23·2-53·5), respectively, in the control arm. Rate ratios did not differ by cancer stage, but were lower for adenocarcinoma (0·31, 0·14-0·69) than for squamous-cell carcinoma (0·78, 0·49-1·25). The rate ratio was lowest in women aged 30-34 years (0·36, 0·14-0·94).nnnINTERPRETATIONnHPV-based screening provides 60-70% greater protection against invasive cervical carcinomas compared with cytology. Data of large-scale randomised trials support initiation of HPV-based screening from age 30 years and extension of screening intervals to at least 5 years.nnnFUNDINGnEuropean Union, Belgian Foundation Against Cancer, KCE-Centre dExpertise, IARC, The Netherlands Organisation for Health Research and Development, the Italian Ministry of Health.

HPV testing in combination with liquid-based cytology in primary cervical screening (ARTISTIC): a randomised controlled trial.

BACKGROUNDnTesting for human papillomavirus (HPV) DNA is reportedly more sensitive than cytology for the detection of high-grade cervical intraepithelial neoplasia (CIN). The effectiveness of HPV testing in primary cervical screening was assessed in the ARTISTIC trial, which was done over two screening rounds approximately 3 years apart (2001-03 and 2004-07) by comparing liquid-based cytology (LBC) combined with HPV testing against LBC alone.nnnMETHODSnWomen aged 20-64 years who were undergoing routine screening as part of the English National Health Service Cervical Screening Programme in Greater Manchester were randomly assigned (between July, 2001, and September, 2003) in a ratio of 3:1 to either combined LBC and HPV testing in which the results were revealed and acted on, or to combined LBC and HPV testing where the HPV result was concealed from the patient and investigator. The primary outcome was the detection rate of cervical intraepithelial neoplasia grade 3 or worse (CIN3+) in the second screening round, analysed by intention to treat. This trial is registered with the International Standard Randomised Controlled Trial Number ISRCTN25417821.nnnFINDINGSnThere were 24 510 eligible women at entry (18 386 in the revealed group, 6124 in the concealed group). In the first round of screening 233 women (1.27%) in the revealed group had CIN3+, compared with 80 (1.31%) women in the concealed group (odds ratio [OR] 0.97, 95% CI 0.75-1.25; p>0.2). There was an unexpectedly large drop in the proportion of women with CIN3+ between the first and second rounds of screening in both groups, at 0.25% (29 of 11 676) in the revealed group and 0.47% (18 of 3866 women) in the concealed group (OR 0.53, 95% CI 0.30-0.96; p=0.042). For both rounds combined, the proportion of women with CIN3+ were 1.51% (revealed) and 1.77% (concealed) (OR 0.85, 95% CI 0.67-1.08; p>0.2).nnnINTERPRETATIONnLBC combined with HPV testing resulted in a significantly lower detection rate of CIN3+ in the second round of screening compared with LBC screening alone, but the effect was small. Over the two screening rounds combined, co-testing did not detect a higher rate of CIN3+ or CIN2+ than LBC alone. Potential changes in screening methodology should be assessed over at least two screening rounds.nnnFUNDINGnNational Institute of Health Research Health Technology Assessment Programme.

Cervical HPV infection and neoplasia in a large population-based prospective study: the Manchester cohort

Cytology and histology records and cervical samples for HPV assay were obtained from a prospective cohort of 49u2009655 women attending clinics for routine cervical cytology in or near Manchester between 1988 and 1993. The women were followed up for cytological abnormality and neoplasia through the cytology laboratorys records. HPV at entry was assayed in an age- and period-stratified random sample of 7278 women and in prevalent and incident CIN3 cases. The prevalence of newly diagnosed CIN3 increased with time since last normal smear, indicating that most cases persist for several years. CIN3 prevalence did not increase further for screening intervals exceeding 5 years, however, suggesting that CIN3 eventually regresses cytologically. CIN2 prevalence increased less steeply with screening interval, while the prevalence of lesser abnormality was almost independent of screening interval. The prevalence of oncogenic HPV at entry declined from 19% among women aged under 25 to less than 3% at age 40 or above. Oncogenic HPV infection was strongly predictive of subsequent CIN3 (OR 17.2, 95% CI 10.4–28.4), but only weakly related to CIN2 (OR 2.3, 95% CI 0.5–10.7) and lesser abnormality (OR 1.4, 95% CI 0.8–2.5). At current incidence rates, the lifetime risk of developing CIN3 will be 9% in this population. The cumulative risk of CIN3 diagnosis among cytologically normal women with oncogenic HPV detected at entry was 28% (CI 18–43%) after 14 years. Persistence of oncogenic HPV may be more sensitive and specific than cytology for early detection of CIN3 and invasive cancer.

HPV testing in routine cervical screening: cross sectional data from the ARTISTIC trial

To evaluate the effectiveness of human papillomavirus (HPV) testing in primary cervical screening. This was a cross-sectional study from the recruitment phase of a prospective randomised trial. Women were screened for HPV in addition to routine cervical cytology testing. Greater Manchester, attendees at routine NHS Cervical Screening Programme. In all, 24u2009510 women aged 20–64 screened with liquid-based cytology (LBC) and HPV testing at entry. HPV testing in primary cervical screening. Type-specific HPV prevalence rates are presented in relation to age as well as cytological and histological findings at entry. In all, 24u2009510 women had adequate cytology and HPV results. Cytology results at entry were: 87% normal, 11% borderline or mild, 1.1% moderate and 0.6% severe dyskaryosis or worse. Prevalence of HPV decreased sharply with age, from 40% at age 20–24 to 12% at 35–39 and 7% or less above age 50. It increased with cytological grade, from 10% of normal cytology and 31% of borderline to 70% mild, 86% moderate, and 96% of severe dyskaryosis or worse. HPV 16 or HPV 18 accounted for 64% of infections in women with severe or worse cytology, and one or both were found in 61% of women with severe dyskaryosis but in only 2.2% of those with normal cytology. The majority of young women in Greater Manchester have been infected with a high-risk HPV by the age of 30. HPV testing is practicable as a primary routine screening test, but in women aged under 30 years, this would lead to a substantial increase in retesting and referral rates. HPV 16 and HPV 18 are more predictive of underlying disease, but other HPV types account for 30% of high-grade disease.

Occupational, domestic and environmental mesothelioma risks in the British population: a case-control study

We obtained lifetime occupational and residential histories by telephone interview with 622 mesothelioma patients (512 men, 110 women) and 1420 population controls. Odds ratios (ORs) were converted to lifetime risk (LR) estimates for Britons born in the 1940s. Male ORs (95% confidence interval (CI)) relative to low-risk occupations for >10 years of exposure before the age of 30 years were 50.0 (25.8–96.8) for carpenters (LR 1 in 17), 17.1 (10.3–28.3) for plumbers, electricians and painters, 7.0 (3.2–15.2) for other construction workers, 15.3 (9.0–26.2) for other recognised high-risk occupations and 5.2 (3.1–8.5) in other industries where asbestos may be encountered. The LR was similar in apparently unexposed men and women (∼1 in 1000), and this was approximately doubled in exposed workers’ relatives (OR 2.0, 95% CI 1.3–3.2). No other environmental hazards were identified. In all, 14% of male and 62% of female cases were not attributable to occupational or domestic asbestos exposure. Approximately half of the male cases were construction workers, and only four had worked for more than 5 years in asbestos product manufacture.

ARTISTIC: A randomised trial of human papillomavirus (HPV) testing in primary cervical screening

OBJECTIVESnPrimary cervical screening uses cytology to detect cancer precursor lesions [cervical intraepithelial neoplasia stage 3 or beyond (CIN3+)]. Human papillomavirus (HPV) testing could add sensitivity as an adjunct to cytology or as a first test, reserving cytology for HPV-positive women. This study addresses the questions: Does the combination of cytology and HPV testing achieve a reduction in incident CIN3+?; Is HPV testing cost-effective in primary cervical screening?; Is its use associated with adverse psychosocial or psychosexual effects?; and How would it perform as an initial screening test followed by cytology for HPV positivity?nnnDESIGNnARTISTIC was a randomised trial of cervical cytology versus cervical cytology plus HPV testing, evaluated over two screening rounds, 3 years apart. Round 1 would detect prevalent disease and round 2 a combination of incident and undetected disease from round 1.nnnSETTINGnWomen undergoing routine cervical screening in the NHS programme in Greater Manchester.nnnPARTICIPANTSnIn total 24,510 women aged 20-64 years were enrolled between July 2001 and September 2003.nnnINTERVENTIONSnHPV testing was performed on the liquid-based cytology (LBC) sample obtained at screening. Women were randomised in a ratio of 3:1 to have the HPV test result revealed and acted upon if persistently positive in cytology-negative cases or concealed. A detailed health economic evaluation and a psychosocial and psychosexual assessment were also performed.nnnMAIN OUTCOME MEASURESnThe primary outcome was CIN3+ in round 2. Secondary outcomes included an economic assessment and psychosocial effects. A large HPV genotyping study was also conducted.nnnRESULTSnIn round 1 there were 313 CIN3+ lesions, representing a prevalence in the revealed and concealed arms of 1.27% and 1.31% respectively (p = 0.81). Round 2 (30-48 months) involved 14,230 (58.1%) of the women screened in round 1 and only 31 CIN3+ were detected; the CIN3 rate was not significantly different between the revealed and concealed arms. A less restrictive definition of round 2 (26-54 months) increased CIN3+ to 45 and CIN3+ incidence in the arms was significantly different (p = 0.05). There was no difference in CIN3+ between the arms when rounds 1 and 2 were combined. Prevalence of high-risk HPV types was age-dependent. Overall prevalence of HPV16/18 increased with severity of dyskaryosis. Mean costs per woman in round 1 were 72 pounds and 56 pounds for the revealed and concealed arms (p < 0.001); an age-adjustment reduced these mean costs to 65 pounds and 52 pounds. Incremental cost-effectiveness ratio for detecting additional CIN3+ by adding HPV testing to LBC screening in round 1 was 38,771 pounds. Age-adjusted mean cost for LBC primary screening with HPV triage was 39 pounds compared with 48 pounds for HPV primary screening with LBC triage. HPV testing did not appear to cause significant psychosocial distress.nnnCONCLUSIONSnRoutine HPV testing did not add significantly to the effectiveness of LBC in this study. No significant adverse psychosocial effects were detected. It would not be cost-effective to screen with cytology and HPV combined but HPV testing, as either triage or initial test triaged by cytology, would be cheaper than cytology without HPV testing. LBC would not benefit from combination with HPV; it is highly effective as primary screening but HPV testing has twin advantages of high negative predictive value and automated platforms enabling high throughput. HPV primary screening would require major contraction and reconfiguration of laboratory services. Follow-up continues in ARTISTIC while maintaining concealment for a further 3-year round of screening, which will help in screening protocol development for the post-vaccination era.

A comparison of HPV DNA testing and liquid based cytology over three rounds of primary cervical screening: Extended follow up in the ARTISTIC trial

BACKGROUNDnThe additional sensitivity of HPV testing compared with cytology could permit extended cervical screening intervals. We wished to determine, through a further (third) round of screening in the ARTISTIC trial, the protection provided by a negative baseline HPV screen compared with that of cytology over a 6 year period.nnnMETHODSnCumulative rates of CIN2 or worse (CIN2+) and CIN3 or worse (CIN3+) were correlated with baseline HPV status and cytology. HPV was detected using the Hybrid Capture 2 (Qiagen) assay for high risk types and genotyped using the Linear Array (Roche) and Papillocheck (Greiner) assays. LBC was performed using ThinPrep (Hologic).nnnFINDINGSnRound 3 included 8,873 women of whom 6,337 had been screened in both rounds 1 and 2 and 2,536 had not been screened since round 1. The median duration of follow-up was 72.7 months. The cumulative rate of CIN2+ over three rounds was 3.88% (95%CI 3.59%, 4.17%) overall; 2.39% in round 1, 0.78% in round 2 and 0.74% in round 3. Cumulative rates by baseline status were 20.53% (95%CI 19.04%, 22.08%) for abnormal cytology, 20.12% (95%CI 18.68%, 21.61%) for HPV detection, 1.41% (95%CI 1.19%, 1.65%) for negative cytology and 0.87% (95%CI 0.70%, 1.06%) for a negative HPV test. In HPV negative women aged over 50 the cumulative rate was 0.16% (95%CI 0.07%, 0.34%). Women who were HPV positive/cytology negative at entry had a cumulative CIN2+ rate of 7.73% (95%CI 6.29%, 9.36%) over 6 years, twice the overall rate.nnnINTERPRETATIONnA negative HPV test was significantly more protective than normal cytology over three rounds. The findings of this extension of ARTISTIC suggest that the screening interval could be extended to 6 years if HPV testing replaced cytology as the primary screening test.

The clinical effectiveness and cost-effectiveness of primary human papillomavirus cervical screening in England: extended follow-up of the ARTISTIC randomised trial cohort through three screening rounds.

BACKGROUNDnThe ARTISTIC (A Randomised Trial In Screening To Improve Cytology) trial originally reported after two rounds of primary cervical screening with human papillomavirus (HPV). Extended follow-up of the randomised trial cohort through a third round could provide valuable insight into the duration of protection of a negative HPV test, which could allow extended screening intervals. If HPV primary screening is to be considered in the national programme, then determining its cost-effectiveness is key, and a detailed economic analysis using ARTISTIC data is needed.nnnAIMS/OBJECTIVESn(1) To determine the round 3 and cumulative rates of cervical intraepithelial neoplasia (CIN) grade 2 or worse (2+) and CIN grade 3 or worse (CIN3+) between the revealed and concealed arms of ARTISTIC after three screening rounds over 6 years. (2) To compare the cumulative incidence of CIN2+ over three screening rounds following negative screening cytology with that following negative baseline HPV. (3) To determine whether or not HPV screening could safely extend the screening interval from 3 to 6 years. (4) To study the potential clinical utility of an increased cut-off of 2 relative light unit/mean control (RLU/Co) for Hybrid Capture 2 (HC2) and HPV genotyping in primary cervical screening. (5) To determine the potential impact of HPV vaccination with Cervarix™ in terms of preventing abnormal cytology and CIN2+. (6) To determine the cost-effectiveness of HPV primary screening compared with current practice using cervical cytology in England.nnnDESIGNnThe ARTISTIC study cohort was recalled for a third round of screening 3 years after round 2 and 6 years following their enrolment to the study. Both arms of the original trial used a single protocol during round 3.nnnSETTINGnARTISTIC study cohort undergoing cervical screening in primary care in Greater Manchester, UK.nnnPARTICIPANTSnBetween July 2007 and September 2009, 8873 women participated in round 3; 6337 had been screened in round 2 and 2536 had not been screened since round 1.nnnINTERVENTIONSnAll women underwent liquid-based cytology and HPV testing and genotyping. Colposcopy was offered to women with moderate dyskaryosis or worse and with HPV-positive mild dyskaryosis/borderline changes. Women with negative cytology or HPV-negative mild dyskaryosis/borderline changes were returned to routine recall.nnnMAIN OUTCOME MEASURESnPrincipal outcomes were cumulative rates of CIN2+ over three screening rounds by cytology and HPV status at entry; HPV type specific rates of CIN2+; effect of age on outcomes correlated with cytology and HPV status; comparison of HC2 cut-off RLU/Co of both 1 and 2; and cost-effectiveness of HPV primary screening.nnnRESULTSnThe median duration of follow-up was 72.7 months in round 3. Over the three screening rounds, there was no significant difference in CIN2+ [odds ratio (OR): 1.06, 95% confidence interval (CI) 0.89 to 1.26, pu2009=u20090.5)] or CIN3+ (OR: 0.90, 95% CI 0.72 to 1.14, pu2009=u20090.4) rates between the trial arms (revealed vs. concealed). Overall, 16% of women were HC2 positive at entry, decreasing from 40% in women aged 20-24 years to around 7% in women aged over 50 years. Abnormal cytology rates at entry were 13% for borderline+ and 2% for moderate+ cytology. Following positive cytology at entry, the cumulative rate of CIN2+ was 20.5%, and was 20.1% following a HPV-positive result at baseline. The cumulative CIN2+ rate for women who were HPV negative at baseline was only 0.87% (95% CI 0.70% to 1.06%) after three rounds of screening, significantly lower than that for women with negative cytology, which was 1.41% (95% CI 1.19% to 1.65%). Women who were HPV negative at baseline had similar protection from CIN2+ after 6 years as women who were cytology negative at baseline after 3 years. Women who were HPV positive/cytology negative at baseline had a cumulative CIN2+ rate at 6 years of 7.7%, significantly higher than that for women who were cytology positive/HPV negative (3.2%). Women who were HPV type 16 positive at baseline had a cumulative CIN2+ rate over three rounds of 43.6% compared with 20.1% for any HPV-positive test. Using a HC2 cut-off of RLU/Cou2009≥u20092 would maintain acceptable sensitivity and result in 16% fewer HPV-positive results. Typing data suggested that around 55-60% of high-grade cytology and CIN2+, but less than 25% of low-grade cytology, would be prevented by HPV vaccine given current rates of coverage in the UK national programme. For the cost-effectiveness analysis, most of the primary HPV strategies examined where HPV was used as the sole primary test were cost saving in both unvaccinated and vaccinated cohorts under baseline cost assumptions, with a 7-18% reduction in annual screening-associated costs in unvaccinated cohorts and a 9-22% reduction for vaccinated cohorts. Utilising partial genotyping at the primary screening stage to identify women with HPV 16/18 and referring them to colposcopy was the most effective strategy (barring co-testing, which is significantly more costly than any other strategies considered), resulting in 83 additional life-years per 100,000 women for unvaccinated women when compared with current practice, and similar life-years saved compared with current practice for vaccinated women. In unvaccinated cohorts, however, this genotyping strategy is predicted to result in a 20% increase in the number of colposcopies performed in England, although in vaccinated cohorts the number of colposcopy referrals was predicted to be lower than in current practice. For all strategies in which HPV is used as the sole primary screening test, decreasing the follow-up interval for intermediate-risk women from 24 to 12 months increased the overall effectiveness of primary HPV screening. In exploratory analysis, strategies for which cytology screening was retained until either age 30 or 35 years, and for which HPV testing was used at older ages, were predicted to be of higher costs and intermediate effectiveness than those associated with full implementation of primary HPV screening from age 25 years. However, this finding should be interpreted with caution as it depends on assumptions made about screening behaviour and compliance with recommendations at the switch over point.nnnCONCLUSIONSnHPV testing as an initial screen was significantly more protective over three rounds (6 years) than the current practice of cytology and the use of primary HPV screening could allow a safe lengthening of the screening interval. A substantial decrease in high-grade cytology and CIN2+ can be expected as a consequence of the HPV vaccination programme. A HC2 cut-off of 2RLU/Co instead of the manufacturers recommended cut-off of 1 would be clinically beneficial in terms of an optimal balance between sensitivity and specificity. Modelled analysis predicts that primary HPV screening would be both more effective and cost saving compared with current practice with cervical cytology for a number of potential strategies in both unvaccinated and vaccinated cohorts. Compliance with surveillance and optimal management of HPV-positive/cytology-negative women after primary HPV screening is of key importance. Limitations of the economic investigation included the need to make assumptions around compliance with screening attendance and follow-up for longer screening intervals in the future, assumptions regarding maintenance of current uptake vaccination in the future, and assumptions regarding the stability of cost of HPV and cytology tests in the future. Detailed sensitivity analysis across a range of possible assumptions was conducted to address these issues. This study and the economic evaluation lend support to convert from cytology to HPV-based screening. Future work should include researching (i) the attitudes of women who test HPV positive/cytology negative, (ii) the value of complementary biomarkers and (iii) activities relevant to primary HPV screening in unvaccinated and vaccinated populations from the point of view of QALY assessment.nnnSTUDY REGISTRATIONnCurrent Controlled Trials ISRCTN25417821.

Optimal Threshold for a Positive Hybrid Capture 2 Test for Detection of Human Papillomavirus: Data from the ARTISTIC Trial

ABSTRACT We present data on the use of the Hybrid Capture 2 (HC2) test for the detection of high-risk human papillomavirus (HR HPV) with different thresholds for positivity within a primary screening setting and as a method of triage for low-grade cytology. In the ARTISTIC population-based trial, 18,386 women were screened by cytology and for HPV. Cervical intraepithelial neoplasia lesions of grade two and higher (CIN2+ lesions) were identified for 453 women within 30 months of an abnormal baseline sample. When a relative light unit/cutoff (RLU/Co) ratio of ≥1 was used as the threshold for considering an HC2 result positive, 15.6% of results were positive, and the proportion of CIN2+ lesions in this group was 14.7%. The relative sensitivity for CIN2+ lesion detection was 93.4%. When an RLU/Co ratio of ≥2 was used as the threshold, there was a 2.5% reduction in positivity, with an increase in the proportion of CIN2+ lesions detected. The relative sensitivity decreased slightly, to 90.3%. Among women with low-grade cytology, HPV prevalences were 43.7% and 40.3% at RLU/Co ratios of ≥1 and ≥2, respectively. The proportions of CIN2+ lesions detected were 17.3% and 18.0%, with relative sensitivities of 87.7% at an RLU/Co ratio of ≥1 and 84.2% at an RLU/Co ratio of ≥2. At an RLU/Co ratio of ≥1, 68.3% of HC2-positive results were confirmed by the Roche line blot assay, compared to 77.2% of those at an RLU/Co ratio of ≥2. Fewer HC2-positive results were confirmed for 35- to 64-year-olds (50.3% at an RLU/Co ratio of ≥1 and 63.2% at an RLU/Co ratio of >2) than for 20- to 34-year-olds (78.7% at an RLU/Co ratio of ≥1 and 83.7% at an RLU/Co ratio of >2). If the HC2 test is used for routine screening as an initial test or as a method of triage for low-grade cytology, we would suggest increasing the threshold for positivity from the RLU/Co ratio of ≥1, recommended by the manufacturer, to an RLU/Co ratio of ≥2, since this study has shown that a beneficial balance between relative sensitivity and the proportion of CIN2+ lesions detected is achieved at this threshold.