Projected Impact of HPV and LBC Primary Testing on Rates of Referral for Colposcopy in a Canadian Cervical Cancer Screening Program

Preliminary outcomes of the Cervical Cancer Screening Program of Northern Portugal: A snapshot

BACKGROUND

Cervical cancer screening remains an essential preventive tool worldwide. First line high-risk Human Papillomavirus (HrHPV) genotyping became gold standard for cervical cancer screening, and has been adopted by several countries, including Portugal. Herein, we aimed to assess the early outcomes of the regional Cervical Cancer Screening Program of Northern Portugal.

METHODS

The analysis of a representative set of cases evaluated during a one-month period (January 2020), with adequate follow-up was performed. Descriptive analysis was performed.

RESULTS

Overall, 7278 samples were received, of which 15.2% were HrHPV positive, most of these disclosing a negative result in subsequent liquid-based cytology. Nearly half of the HrHPV-positive women were referred to colposcopy. Within this group, HPV16/18+ cases depicted the higher frequency of high-grade squamous intraepithelial lesion (HSIL) or worse, compared with abnormal cytology or persistent HrHPV infection. Among women with non-HPV16/18 HrHPV infection and negative cytology, which are eligible for repeat sampling in one year, 65% were re-tested. Importantly, nearly half of these cleared HrHPV infection. Furthermore, referral to colposcopy due to HPV16/18 infection and/or abnormal cytology results were associated with > 40% risk for HSIL or worse lesion.

CONCLUSIONS

Our study confirmed the reliability and effectiveness of first line HrHPV genotyping in the Cervical Cancer Screening Program of Northern Portugal. Nonetheless, it also raised concerns about excessive referral to colposcopy, with the inherent human and financial costs. Thus, further improvement and optimization are key to ensure the sustainability of the program.

Colposcopy referral rates post-introduction of primary screening with human papillomavirus testing: evidence from a large British Columbia cohort study

Background

Shifting from cytology to human papillomavirus (HPV)-based cervical cancer screening will initially increase colposcopy referrals. The anticipated impact on health systems has been raised as a concern for implementation. It is unclear if the higher rate of colposcopy referrals is sustained after initial HPV-based screens or reverts to new lower baselines due to earlier detection and treatment of precancer. This study aimed to investigate long-term rates of colposcopy referrals after participation in HPV-based screening.

Methods

Participants of HPV for Cervical Cancer Screening trial (HPV FOCAL) received one (HPV1, N = 6204) or two (HPV2, N = 9540) HPV-based screens. After exit, they returned to British Columbia's (BC) cytology screening program. A comparison cohort from the BC screening population (BCS, N = 1,140,745) was identified, mirroring trial inclusion criteria. All participants were followed for 10-14 years through the provincial screening registry. Colposcopy referral rates per 1000 screens were calculated for each group. Trial colposcopy referrals for HPV1 and HPV2 were calculated under two referral scenarios: (1) all HPV positive referred to colposcopy; (2) cytology triage with ASCUS or greater referred to colposcopy. Colposcopy referrals from post-trial screens in HPV1 an HPV2 and all screens in BCS were based on actual recommendations from the screening program. A multivariable flexible survival regression model compared hazard ratios (HR) throughout follow-up.

Findings

Scenario 2 referral rates were higher during initial HPV screen(s) vs cytology screen (HPV1: 28 per 1000 screens (95% CI: 24, 33), HPV2: 32 per 1000 screens (95% CI: 29, 36), BCS: 8 per 1000 screens (95% CI: 8.9)). However, post-trial rates in HPV1 and HPV2 were significantly lower than in BCS. Cumulative rates in HPV1 and HPV2 approached the cumulative rate in BCS 11-12 years after HPV-based screening (HPV1: 11 per 1000 screens (95% CI: 10, 12), HPV2: 16 per 1000 screens (95% CI: 15-17), BCS: 11 per 1000 screens (95% CI: 10, 11)). Adjusted models demonstrated reductions in referral rates in HPV1 (HR = 0.6, 95% CI: 0.5, 0.7) and HPV2 (HR = 0.7, 95% CI: 0.6, 0.8) relative to BCS by 54 and 72 months post-final HPV screen respectively.

Interpretation

Reduced colposcopy referral rates were observed after initial rounds of HPV-based screening. After initial HPV screening, referral rates to colposcopy after cytology triage were below the current rates seen in a centralized cytology program after approximately four years. Any expected increase in referrals at initiation of HPV-based screening could be countered by staged program implementation.

Funding

This work was supported by the National Institutes of Health (R01 CA221918), Michael Smith Health Research BC (RT-2021-1595), and the Canadian Institutes of Health Research (MCT82072).

Long-term cervical precancer outcomes after a negative DNA- or RNA-based human papillomavirus test result

BACKGROUND

Cervical cancer, a preventable disease associated with the human papillomavirus, is responsible for significant morbidity and mortality globally. Primary human papillomavirus testing is more sensitive in detecting precancerous cervical lesions than cytologic screening and can be conducted using either DNA- or RNA-based assays. Screening programs must select the most appropriate assay from several available assays for their population. It is not yet known whether these assays perform equivalently in the long term, particularly among women with a negative human papillomavirus test result. This study aims to compare long-term safety after a negative human papillomavirus test result across both DNA- and RNA-based testing assays.

OBJECTIVE

This study aimed to compare long-term high-grade cervical intraepithelial neoplasia (grade 2 or higher and grade 3 or higher) outcomes of 2 DNA-based assays (Digene Hybrid Capture 2 High-Risk HPV DNA Test and cobas 4800 HPV Test) and 1 messenger RNA-based assay (Aptima HPV Assay) using data from the Human Papillomavirus For Cervical Cancer Trial-DECADEl (FOCAL-DECADE) cohort, by first comparing the positive and negative rates between the assays and then investigating the cumulative incidence of cervical intraepithelial neoplasia grade 2 and higher and grade 3 or higher detection among participants in the FOCAL DECADE cohort over follow-up according to human papillomavirus testing assays.

STUDY DESIGN

The FOCAL Trial was a randomized controlled trial that evaluated human papillomavirus testing for primary cervical cancer screening. The FOCAL-DECADE cohort subsequently followed FOCAL Trial participants passively through the British Columbia Cervix Screening Program Database for approximately 10 years after the FOCAL Trial study exit to examine the rates of cervical intraepithelial neoplasia grade 2 or higher and grade 3 or higher. For this study, eligible participants had baseline human papillomavirus-negative results from at least 1 assay and had 1 or more cytologic screens after baseline (9509 participants for DNA-based and 3473 participants for DNA- vs RNA-based assay comparisons). We constructed cumulative incidence curves and compared the hazard ratios for cervical intraepithelial neoplasia grade 2 or higher and grade 3 or higher detection according to the assays.

RESULTS

Over 10 years of follow-up, the cumulative incidence of cervical intraepithelial neoplasia grade 2 or higher and grade 3 or higher did not significantly differ between the DNA-based assays (hazard ratio, 0.95; 95% confidence interval, 0.84-1.06; P=.35 and hazard ratio, 0.82; 95% confidence interval, 0.66-1.01; P=.06 for cervical intraepithelial neoplasia grade 2 or higher and cervical intraepithelial neoplasia grade 3 or higher, respectively) or between the DNA- and RNA-based assays (hazard ratio, 0.97; 95% confidence interval, 0.87-1.06; P=.48 and hazard ratio, 0.94; 95% confidence interval, 0.79-1.13; P=.52 for cervical intraepithelial neoplasia grade 2 or higher and cervical intraepithelial neoplasia grade 3 or higher, respectively).

CONCLUSION

Among participants who tested negative for human papillomavirus at baseline, the long-term risk of cervical intraepithelial neoplasia grade 2 or higher and grade 3 or higher did not significantly differ regardless of whether DNA- or RNA-based human papillomavirus testing assays were used. Screening program decision makers can be confident that for women who test negative for human papillomavirus, DNA- and RNA-based assays exhibit similar cervical intraepithelial neoplasia grade 2 or higher outcomes over several years.

Implementation considerations using HPV self-collection to reach women under-screened for cervical cancer in high-income settings

The success of cytology (Pap screening) programs is undeniable and has drastically reduced cervical cancer rates in high-income settings where it has been implemented [...]

Optimizing secondary prevention of cervical cancer: Recent advances and future challenges

Although human papillomavirus (HPV) vaccines offer enormous promise for the ultimate control and possible elimination of cervical cancer, barriers to uptake and coverage of the vaccine both in high- and low/middle-income settings mean that advances in secondary prevention continue to be essential to prevent unnecessary deaths and suffering from cervical cancer for decades to come. While cytology (the Pap smear) has reduced cervical cancer incidence and prevalence in jurisdictions where it has been systematically implemented in population-based programs-mainly in high-income settings-limitations inherent to this method, and to program delivery, leave many women still vulnerable to cervical cancer. Recent evidence has confirmed that screening based on HPV testing prevents more invasive cervical cancer and precancerous lesions, and offers innovative options such as self-collection of specimens to improve screening uptake broadly. In this paper, we review key advances, future opportunities, and ongoing challenges for secondary prevention of cervical cancer using HPV-based testing.

Choosing wisely: a model-based analysis evaluating the trade-offs in cancer benefit and diagnostic referrals among alternative HPV testing strategies in Norway

Background:

Forthcoming cervical cancer screening strategies involving human papillomavirus (HPV) testing for women not vaccinated against HPV infections may increase colposcopy referral rates. We quantified health and resource trade-offs associated with alternative HPV-based algorithms to inform decision-makers when choosing between candidate algorithms.

Methods:

We used a mathematical simulation model of HPV-induced cervical carcinogenesis in Norway. We compared the current cytology-based strategy to alternative strategies that varied by the switching age to primary HPV testing (ages 25–34 years), the routine screening frequency (every 3–10 years), and management of HPV-positive, cytology-negative women. Model outcomes included reductions in lifetime cervical cancer risk, relative colposcopy rates, and colposcopy rates per cervical cancer prevented.

Results:

The age of switching to primary HPV testing and the screening frequency had the largest impacts on cancer risk reductions, which ranged from 90.9% to 96.3% compared to no screening. In contrast, increasing the follow-up intensity of HPV-positive, cytology-negative women provided only minor improvements in cancer benefits, but generally required considerably higher rates of colposcopy referrals compared to current levels, resulting in less efficient cervical cancer prevention.

Conclusions:

We found that in order to maximise cancer benefits HPV-based screening among unvaccinated women should not be delayed: rather, policy makers should utilise the triage mechanism to control colposcopy referrals.

Approaches for triaging women who test positive for human papillomavirus in cervical cancer screening

Substantial evidence exists to support the introduction of molecular testing for human papillomavirus (HPV) as the primary technology in cervical cancer screening. While HPV testing is much more sensitive than cytology for detection of high-grade precancerous lesions, it is less specific. To improve efficiency, it is therefore recommended that a specific test (like cytology) be used in triaging HPV positive women to colposcopy. A number of studies have been conducted that support the use of cytology alone or in conjunction with HPV genotyping for triage. The decision to incorporate genotyping also depends on the commercial HPV test that is selected since not all tests provide results for certain individual high-risk types. Regardless of whether policy officials decide to adopt a triage approach that incorporates genotyping, the use of liquid based cytology (LBC) may also improve screening performance by reducing diagnostic delays. With LBC, the same cell suspension from a single collection may be used for HPV testing and a smear can be immediately prepared if HPV status is positive. This was a critical lesson from a community based demonstration project in Montreal (VASCAR study), where conventional cytology exists and specimen co-collection was not permitted for ethical reasons, requiring HPV positive women to return for an additional screening visit prior to colposcopy.

Disease detection and resource use in the safety and control arms of the HPV FOCAL cervical cancer screening trial

Background:

The HPV FOCAL Trial is a RCT comparing human papilloma virus (HPV) with Liquid Based Cytology (LBC) screening for cervical cancer. Results are presented for the comparison of the Safety and Control arms after two rounds.

Methods:

HPV FOCAL included randomisation of women aged 25–65 into the Safety arm, where they were initially screened with HPV and the Control arm, where they received entry screening with LBC, with both arms screened again with LBC at 24 months.

Results:

There are 6203 (Safety) and 6075 (Control) women included in this analysis. For the Safety vs Control arms, Round 1 screening resulted in increased detection of cervical intraepithelial neoplasia 2 or worse (CIN2+),15.3 vs 10.4 per 1000, RR=1.48 (95%CI=1.08–2.03) and higher colposcopy referral rates, 5.6% vs 3.2%. LBC screening at 24 months resulted in similar colposcopy referral rates, 1.5% vs 1.9%, and decreased CIN2+ detection, 2.0 vs 4.7 per 1000, RR=0.43 (95%CI=0.21–0.88) in the Safety vs Control arms. CIN2+ detection and colposcopy referral rates declined with increasing age in both arms. One round of HPV screening detected similar levels of CIN2+ as two rounds of LBC screening.

Interpretation:

CIN2+ detection at 2 years was lower in those screened by HPV, indicating an improved 2-year negative predictive value of the HPV test.

Cervical cancer incidence in British Columbia: Predicting effects of changes from Pap to human papillomavirus screening and of changes in screening participation

Objectives To estimate the impact of increased participation in screening, and of the proposed change from Pap to human papillomavirus screening on the incidence of cervical cancer in British Columbia. Methods For invasive cervical cancer cases diagnosed in British Columbia between 2002 and 2011, data were extracted on age and cancer morphology from the British Columbia Cancer Registry, and Pap screening history was obtained from the British Columbia Cervical Cancer Screening Program database. Only screening performed two to seven years prior to diagnosis was assumed to reduce subsequent risk of cancer. Results from randomized trials of human papillomavirus versus cytology screening and population based estimates of cytology screening were used to estimate the effect of a change in screening test and increases in participation. Results Between 2002 and 2011, there were 1663 cases of cervical cancer reported; 660 (367 squamous and 293 non-squamous) were eligible and screened two to seven years prior to diagnosis. The predicted reduction by changing to human papillomavirus screening was 363 (95% confidence interval = 124-496) representing 22% of all cases. If 50% of subjects not screened two to seven years prior had undergone Pap screening, it is projected that a further 268 cases (16%) could have been prevented; if they had undergone human papillomavirus screening, a further 365 cases (22%) could have been prevented. Conclusions For many women who develop cervical cancer, primary human papillomavirus testing could have substantially reduced their cancer risk. Human papillomavirus rather than Pap testing would further increase the gains from any increases in population screening participation.

Using the Cancer Risk Management Model to evaluate the health and economic impacts of cytology compared with human papillomavirus DNA testing for primary cervical cancer screening in Canada

BACKGROUND

In Canada, discussion about changing from cytology to human papillomavirus (hpv) dna testing for primary screening in cervical cancer is ongoing. However, the Canadian Task Force on Preventive Health Care has not yet made a recommendation, concluding that the evidence is insufficient.

METHODS

We used the cervical cancer and hpv transmission models of the Cancer Risk Management Model to study the health and economic outcomes of primary cytology compared with hpv dna testing in 14 screening scenarios with varying screening modalities and intervals. Projected cervical cancer cases, deaths, colposcopies, screens, costs, and incremental cost-effectiveness were evaluated. We performed sensitivity analyses for hpv dna test costs.

RESULTS

Compared with triennial cytology from age 25, 5-yearly hpv dna screening alone from age 30 resulted in equivalent incident cases and deaths, but 55% (82,000) fewer colposcopies and 43% (1,195,000) fewer screens. At hpv dna screening intervals of 3 years, whether alone or in an age-based sequence with cytology, screening costs are greater, but at intervals of more than 5 years, they are lower. Scenarios on the cost-effectiveness frontier were hpv dna testing alone every 10, 7.5, 5, or 3 years, and triennial cytology starting at age 21 or 25 when combined with hpv dna testing every 3 years.

CONCLUSIONS

Changing from cytology to hpv dna testing as the primary screening test for cervical cancer would be an acceptable strategy in Canada with respect to incidence, mortality, screening and diagnostic test volumes.