Impact of a carrageenan gel on viral load of genital human papillomavirus infections in sexually active women: Findings from the Carrageenan-gel Against Transmission of Cervical Human papillomavirus (CATCH) trial

Previous research has shown that women's use of a carrageenan gel reduces the risk of acquiring genital human papillomavirus (HPV) infections but does not help to clear existing ones. Although gel use may not result in complete clearance, it may decrease the viral load of HPV infections. We tested this hypothesis in the Carrageenan-gel Against Transmission of Cervical Human papillomavirus (CATCH) randomized controlled trial. Participants of the CATCH study were selected for viral load testing if they had completed the first four study visits and tested positive for HPV42 or HPV51 in at least one of these visits. HPV42 and HPV51 were chosen as they were among the most abundant low- and high-risk types, respectively, in the study sample. We measured viral load with a type-specific real-time polymerase chain reaction. Results were displayed using summary statistics. Of 461 enrolled participants, 39 were included in the HPV42 analysis set and 56 in the HPV51 analysis set. The median time between visits 1 and 4 was 3.7 months. The viral load (copies/cell) of HPV42 ranged from <0.001 to 13 434.1, and that of HPV51 from <0.001 to 967.1. The net median change in HPV42 viral load over all four visits was -1.04 copies/cell in the carrageenan and -147 copies/cell in the placebo arm (Wilcoxon rank sum test, p = 0.26). There was no net median change in HPV51 viral load over all four visits in either arm (p = 0.45). The use of a carrageenan-based gel is unlikely to reduce the viral load of HPVs 42 or 51.

Detection and Clearance of Type-Specific and Phylogenetically Related Genital Human Papillomavirus Infections in Young Women in New Heterosexual Relationships

BACKGROUND

Understanding the natural history of human papillomavirus (HPV) infections is essential to cervical cancer prevention planning. We estimated HPV type-specific infection detection and clearance in young women.

METHODS

The HPV Infection and Transmission among Couples through Heterosexual activity (HITCH) study is a prospective cohort of 502 college-age women who recently initiated a heterosexual relationship. We tested vaginal samples collected at 6 clinical visits over 24 months for 36 HPV types. Using rates and Kaplan-Meier analysis, we estimated time-to-event statistics with 95% confidence intervals (CIs) for detection of incident infections and clearance of incident and present-at-baseline infections (separately). We conducted analyses at the woman- and HPV-levels, with HPV types grouped by phylogenetic relatedness.

RESULTS

By 24 months, we detected incident infections in 40.4% (CI, 33.4%-48.4%) of women. Incident subgenus 1 (43.4; CI, 33.6-56.4), 2 (47.1; CI, 39.9-55.5), and 3 (46.6; CI, 37.7-57.7) infections cleared at similar rates per 1000 infection-months. We observed similar homogeny in HPV-level clearance rates among present-at-baseline infections.

CONCLUSIONS

Our analyses provide type-specific infection natural history estimates for cervical cancer prevention planning. HPV-level analyses did not clearly indicate that high oncogenic risk subgenus 2 infections persist longer than their low oncogenic risk subgenera 1 and 3 counterparts.

Use of a carrageenan-based gel had no impact on anal HPVs 16 and 18 viral loads in gay, bisexual, and other men who have sex with men

The Lubricant Investigation in Men to Inhibit Transmission of human papillomavirus (HPV) Infection randomized control trial in gay, bisexual, and other men who have sex with men (gbMSM) found that carrageenan use neither reduced acquisition of anal HPV infections nor influenced infection clearance. To investigate carrageenan's lack of protective effect, we compared the change in anal HPV16 and HPV18 viral loads following carrageenan use against placebo. We restricted our analysis to participants who completed the first four study visits and had a valid baseline sample (n = 161, 54 HIV-positive). Samples were tested for HPV detection using the linear array PCR assay. HPV16- and/or HPV18-positive samples were tested for viral load using real-time PCR. For participants who tested HPV16- (n = 29) or HPV18-positive (n = 10) at least once across visits 1-4, we compared the change in type-specific viral load between study arms using the Mann-Whitney U test. Although the median net change in HPV16 and HPV18 viral loads across visits 1-4 was higher in the treatment than placebo arm (HPV16: 0.68 vs. 0.18 copies/cell, p = 0.60; HPV18: 18.32 vs. 10.12 copies/cell, p = 0.52), these differences were not statistically significant. Results were similar by HIV status. Carrageenan use did not impact anal HPV16 or HPV18 viral loads, which may further explain its lack of protective effect in gbMSM.

Epidemiology of genital human papillomavirus infections in sequential male sex partners of young females

OBJECTIVES

Couple-based studies have considered human papillomavirus (HPV) transmission between current heterosexual partners (male↔female). Using data from young women and their sequential male partners, we analysed HPV transmission from upstream sexual partnerships (male 1↔female) to downstream sex partners (→male 2).

METHODS

Among 502 females enrolled in the HPV Infection and Transmission among Couples through Heterosexual activity study (2005-2011, Montréal, Canada), 42 brought one male sex partner at baseline (male 1) and another during follow-up (male 2). Female genital samples, collected at six visits over 24 months, and male genital samples, collected at two visits over 4 months, were tested for 36 HPV types (n = 1512 detectable infections). We calculated observed/expected ratios with 95% CIs for type-specific HPV concordance between males 1 and 2. Using mixed-effects regression, we estimated ORs with 95% CIs for male 2 testing positive for the same HPV type as male 1.

RESULTS

Detection of the same HPV type in males 1 and 2 occurred 2.6 (CI 1.9-3.5) times more often than chance (29 instances observed vs. 10.95 instances expected). The OR for male 2 positivity was 4.2 (CI 2.5-7.0). Adjusting for the number of times the linking female tested positive for the same HPV type attenuated the relationship between male 1 and 2 positivity, suggesting mediation.

CONCLUSIONS

High type-specific HPV concordance between males 1 and 2 confirms HPV's transmissibility in chains of sequential sexual partnerships. HPV positivity in an upstream partnership predicted positivity in a downstream male when the linking female partner was persistently positive.

Serologic response to human papillomavirus genotypes following vaccination: findings from the HITCH cohort study

BACKGROUND

Human papillomavirus (HPV) infection contributes to approximately 5% of the worldwide cancer burden. The three-dose HPV vaccine has demonstrated immunogenicity and efficacy. Humoral responses may be critical for preventing, controlling, and/or eliminating HPV infection. Using data from the HITCH cohort, we analysed humoral immune response to HPV vaccination among women in relation to the phylogenetic relatedness of HPV genotypes.

METHODS

We included 96 women aged 18-24 years attending college or university in Montreal, Canada. Participants provided blood samples at enrolment and five follow-up visits. Antibody response to bacterially expressed L1 and E6 glutathione S-transferase fusion proteins of multiple Alphapapillomavirus types, and to virus-like particles (VLP-L1) of HPV16 and HPV18 were measured using multiplex serology. We assessed correlations between antibody seroreactivities using Pearson correlations (r).

RESULTS

At enrolment, 87.7% of participants were unvaccinated, 2.4% had received one, 3.2% two, and 6.7% three doses of HPV vaccine. The corresponding L1 seropositivity to any HPV was 41.2%, 83.3%, 100%, and 97.0%. Between-type correlations for L1 seroreactivities increased with the number of vaccine doses, from one to three. Among the latter, the strongest correlations were observed for HPV58-HPV33 (Pearson correlation [r] = 0.96; α9-species); HPV11-HPV6 (r = 0.96; α10-species); HPV45-HPV18 (r = 0.95; α7-species), and HPV68-HPV59 (r = 0.95; α7-species).

CONCLUSIONS

Correlations between HPV-specific antibody seroreactivities are affected by phylogenetic relatedness, with anti-L1 correlations becoming stronger with the number of vaccine doses received.

Validation of novel DNA methylation markers in cervical precancer and cancer

We have recently identified, using a genome-wide approach, new methylation markers which were evaluated among various cervical intraepithelial neoplasia (CIN) grades and cervical cancer. We herein validate the methylated state of these genes in independent study populations, based on histology ascertained outcomes regardless of human papillomavirus status. CA10, DPP10, FMN2 and HAS1 (discovery set: 54 normal, 50 CIN1, 40 CIN2, 42 CIN3) were evaluated by targeted bisulfite next generation sequencing (NGS) (Illumina MiSeq platform) in 258 (training set: 100 normal, 50 CIN1, 50 CIN2, 50 CIN3, 8 cancers) and 373 (validation set: 100 normal, 57 CIN1, 61 CIN2, 53 CIN3, 102 cancers) physician-collected samples (PreservCyt). Using targeted amplification NGS data from the training set for 94 normal and eight cancer samples, we calculated for each gene the median methylation value. These were summed and normalized to compute a four-gene Marker Polygenic Score (MPS). We compared the relationship between MPS and progression from normal through CIN grades and cancer, separately in the training and validation sets, and tested its clinical performance via receiver-operating characteristic curves. MPS increased with increasing CIN grade, and accurately predicted cervical cancer in the training (area under the curve, AUC = 0.9950) and validation (AUC = 0.9337) sets, comparing normal to cancer. Using the highest threshold of 100% specificity, sensitivity for detection of cervical cancer was 67.7%; whereas reducing specificity to 95% increased sensitivity to 84.3%. Further evaluation of these biomarkers is warranted in prospective studies.

Cancers Attributable to Infections in the US in 2017: A Meta-Analysis

Importance

Infections are largely modifiable causes of cancer. However, there remains untapped potential for preventing and treating carcinogenic infections in the US.

Objective

To estimate the percentage and number of incident cancers attributable to infections in the US among adults and children for the most recent year cancer incidence data were available (2017).

Data Sources

A literature search from 1946 onward was performed in MEDLINE on January 6, 2023, to obtain the data required to calculate population attributable fractions for 31 infection-cancer pairs. National Health and Nutrition Examination Survey data were used to estimate the population prevalence of hepatitis B and C viruses and Helicobacter pylori.

Study Selection

Studies conducted in the US or other Western countries were selected according to specific infection-cancer criteria.

Data Extraction and Synthesis

Data from 128 studies were meta-analyzed to obtain the magnitude of an infection-cancer association or prevalence of the infection within cancer cells.

Main Outcomes and Measures

The proportion of cancer incidence attributable to 8 infections.

Results

Of the 1 666 102 cancers diagnosed in 2017 among individuals aged 20 years or older in the US, 71 485 (4.3%; 95% CI, 3.1%-5.3%) were attributable to infections. Human papillomavirus (n = 38 230) was responsible for the most cancers, followed by H pylori (n = 10 624), hepatitis C virus (n = 9006), Epstein-Barr virus (n = 7581), hepatitis B virus (n = 2310), Merkel cell polyomavirus (n = 2000), Kaposi sarcoma-associated herpesvirus (n = 1075), and human T-cell lymphotropic virus type 1 (n = 659). Cancers with the most infection-attributable cases were cervical (human papillomavirus; n = 12 829), gastric (H pylori and Epstein-Barr virus; n = 12 565), oropharynx (human papillomavirus; n = 12 430), and hepatocellular carcinoma (hepatitis B and C viruses; n = 10 017). The burden of infection-attributable cancers as a proportion of total cancer incidence ranged from 9.6% (95% CI, 9.2%-10.0%) for women aged 20 to 34 years to 3.2% (95% CI, 2.4%-3.8%) for women aged 65 years or older and from 6.1% (95% CI, 5.2%-7.0%) for men aged 20 to 34 years to 3.3% (95% CI, 1.9%-4.4%) for men aged 65 years or older. Among those aged 19 years or younger, 2.2% (95% CI, 1.3%-3.0%) of cancers diagnosed in 2017 were attributable to Epstein-Barr virus.

Conclusions and Relevance

Infections were estimated to be responsible for 4.3% of cancers diagnosed among adults in the US in 2017 and, therefore, represent an important target for cancer prevention efforts.

Betapapillomavirus natural history and co-detection with alphapapillomavirus in cervical samples of adult women

Human papillomaviruses (HPV) of the genus Betapapillomavirus can infect both cutaneous and mucosal sites, but research on their natural history at mucosal sites remains scarce. We examined the risk factors and co-detection patterns of HPVs of the Betapapillomavirus and Alphapapillomavirus genera in cervical samples of the Ludwig-McGill cohort study. We assessed a subset of 505 women from the Ludwig-McGill cohort study from São Paulo, Brazil. Cervical samples over the first year of follow-up were tested for DNA of over 40 alphapapillomavirus types and 43 betapapillomavirus types using a type-specific multiplex genotyping polymerase chain reaction assay. We assessed the risk factors for prevalent and incident betapapillomavirus type detection, and whether types were detected more frequently together than expected assuming independence using permutation tests, logistic regression, and Cox regression. We observed significant within-genus clustering but not cross-genus clustering. Multiple betapapillomavirus types were co-detected in the same sample 2.24 (95% confidence interval [CI]: 1.65-3.29) times more frequently than expected. Conversely, co-detections of alphapapillomavirus and betapapillomavirus types in the same sample occurred only 0.64 (95% CI: 0.51-0.83) times as often as expected under independence. In prospective analyses, positivity to one HPV genus was associated with a nonsignificant lower incidence of detection of types in the other genus. Lifetime number of sex partners and new sex partner acquisition were associated with lower risks of prevalent and incident betapapillomavirus detection. Betapapillomaviruses are commonly found in the cervicovaginal tract. Results suggest potentially different mechanisms of transmission for betapapillomavirus genital infections other than vaginal sex.

Differences in site-specific cancer incidence by individual- and area-level income in Canada from 2006 to 2015

Income, a component of socioeconomic status, influences cancer risk as a social determinant of health. We evaluated the independent associations between individual- and area-level income and site-specific cancer incidence in Canada. We used data from the 2006 and 2011 Canadian Census Health and Environment Cohorts, which are probabilistically linked datasets constituted by 5.9 million and 6.5 million respondents of the 2006 Canadian long-form census and 2011 National Household Survey, respectively. Individuals were linked to the Canadian Cancer Registry through 2015. Individual-level income was derived using after-tax household income adjusted for household size. Annual tax return postal codes were used to assign area-level income quintiles to individuals for each year of follow-up. We calculated age-standardized incidence rates (ASIR) and rate ratios for cancers overall and by site. We conducted multivariable negative binomial regression to adjust these rates for other demographic and socioeconomic variables. Individuals of lower individual- and area-level income had higher ASIRs compared to those in the wealthiest income quintile for head and neck, oropharyngeal, esophageal, stomach, colorectal, anal, liver, pancreas, lung, cervical and kidney and renal pelvis cancers. Conversely, individuals of wealthier individual- and area-level income had higher ASIRs for melanoma, leukemia, Hodgkin's lymphoma, non-Hodgkin's lymphoma, breast, uterine, prostate and testicular cancers. Most differences in site-specific incidence by income quintile remained after adjustment. Although Canada's publicly funded healthcare system provides universal coverage, inequalities in cancer incidence persist across individual- and area-level income gradients. Our estimates suggest that individual- and area-level income affect cancer incidence through independent mechanisms.

Human Papillomavirus Detectability and Cervical Cancer Prognosis: A Systematic Review and Meta-analysis

OBJECTIVE

To evaluate whether testing positive for human papillomavirus (HPV) before treatment is associated with cervical cancer recurrence and disease-free, cancer-specific, and overall survival and to report the relationship of HPV to cervical cancer histology, stage, grade, tumor size, lymph node involvement, and treatment response.

DATA SOURCES

EMBASE and MEDLINE were searched from inception to January 27, 2022, with the use of MeSH terms and keywords relating to cervical cancer, HPV, and prognosis. ClinicalTrials.gov was not searched because of the nature of our review question.

METHODS OF STUDY SELECTION

Studies must have assessed HPV DNA or RNA in cervical pretreatment biopsies or cells from 20 or more patients with invasive cervical cancer followed up for any length of time and reported the effect of testing positive or negative for HPV on cervical cancer recurrence, disease-free survival, cancer-specific survival, or overall survival. We extracted data on HPV-detection methods, patient and tumor characteristics, and clinical outcomes.

TABULATION, INTEGRATION, AND RESULTS

Hazard ratios (HRs) and 95% CIs were pooled with a random-effects model. Meta-regression was performed to explore heterogeneity. Of 11,179 titles or abstracts and 474 full-text articles reviewed, 77 studies were included in the systematic review. Among these 77 studies, 30 reported on the relationship of HPV status to histology, 39 to cancer stage, 13 to tumor grade, 17 to tumor size, 23 to lymph node involvement, and four to treatment response. Testing positive for HPV was associated with better disease-free survival (HR 0.38, 95% CI 0.25-0.57; 15 studies with 2,564 cases), cancer-specific survival (HR 0.56, 95% CI 0.44-0.71; nine studies with 1,398 cases), and overall survival (HR 0.59, 95% CI 0.47-0.74; 36 studies with 9,169 cases), but not recurrence (HR 0.59, 95% CI 0.33-1.07; eight studies with 1,313 cases). Meta-regression revealed that the number of cases, tumor grade, specimen type, gene target, and HPV prevalence together explained 73.8% of the between-study heterogeneity.

CONCLUSION

This review indicates that HPV detectability in cervical cancer is associated with a better clinical prognosis.

SYSTEMATIC REVIEW REGISTRATION

https://osf.io/dtyeb .

Ascertaining asthma status in epidemiologic studies: a comparison between administrative health data and self-report

BACKGROUND

Studies have suggested that agreement between administrative health data and self-report for asthma status ranges from fair to good, but few studies benefited from administrative health data over a long period. We aimed to (1) evaluate agreement between asthma status ascertained in administrative health data covering a period of 30 years and from self-report, and (2) identify determinants of agreement between the two sources.

METHODS

We used administrative health data (1983-2012) from the Quebec Birth Cohort on Immunity and Health, which included 81,496 individuals born in the province of Quebec, Canada, in 1974. Additional information, including self-reported asthma, was collected by telephone interview with 1643 participants in 2012. By design, half of them had childhood asthma based on health services utilization. Results were weighted according to the inverse of the sampling probabilities. Five algorithms were applied to administrative health data (having ≥ 2 physician claims over a 1-, 2-, 3-, 5-, or 30-year interval or ≥ 1 hospitalization), to enable comparisons with previous studies. We estimated the proportion of overall agreement and Kappa, between asthma status derived from algorithms and self-reports. We used logistic regression to identify factors associated with agreement.

RESULTS

Applying the five algorithms, the prevalence of asthma ranged from 49 to 55% among the 1643 participants. At interview (mean age = 37 years), 49% and 47% of participants respectively reported ever having asthma and asthma diagnosed by a physician. Proportions of agreement between administrative health data and self-report ranged from 88 to 91%, with Kappas ranging from 0.57 (95% CI: 0.52-0.63) to 0.67 (95% CI: 0.62-0.72); the highest values were obtained with the [≥ 2 physician claims over a 30-year interval or ≥ 1 hospitalization] algorithm. Having sought health services for allergic diseases other than asthma was related to lower agreement (Odds ratio = 0.41; 95% CI: 0.25-0.65 comparing ≥ 1 health services to none).

CONCLUSIONS

These findings indicate good agreement between asthma status defined from administrative health data and self-report. Agreement was higher than previously observed, which may be due to the 30-year lookback window in administrative data. Our findings support using both administrative health data and self-report in population-based epidemiological studies.

Human Papillomavirus Intermittence and Risk Factors Associated With First Detections and Redetections in the Ludwig-McGill Cohort Study of Adult Women

BACKGROUND

We assessed the incidence and risk factors for first detection and redetection with the same human papillomavirus (HPV) genotype, and prevalence of cytological lesions during HPV redetections.

METHODS

The Ludwig-McGill cohort study followed women aged 18-60 years from São Paulo, Brazil in 1993-1997 for up to 10 years. Women provided cervical samples for cytology testing and HPV DNA testing at each visit. A redetection was defined as a recurring genotype-specific HPV positive result after 1 or more intervening negative visits. Predictors of genotype-specific redetection were assessed using adjusted hazard ratios (aHR) with Cox regression modeling.

RESULTS

In total, 2184 women contributed 2368 incident HPV genotype-specific first detections and 308 genotype-specific redetections over a median follow-up of 6.5 years. The cumulative incidence of redetection with the same genotype was 6.6% at 1 year and 14.8% at 5 years after the loss of positivity of the first detection. Neither age (aHR 0.90; 95% confidence interval [CI], .54-1.47 for ≥45 years vs < 25 years) nor new sexual partner acquisition (aHR 0.98; 95% CI, .70-1.35) were statistically associated with genotype-specific redetection. High-grade squamous intraepithelial lesion prevalence was similar during first HPV detections (2.9%) and redetection (3.2%).

CONCLUSIONS

Our findings suggest many HPV redetections were likely reactivations of latent recurring infections.

Pan-Canadian survey on the impact of the COVID-19 pandemic on cervical cancer screening and management: cross-sectional survey of healthcare professionals

Background: The COVID-19 pandemic has caused disruptions to cancer care by delaying diagnoses and treatment, presenting challenges and uncertainties for both patients and physicians. We conducted a nationwide online survey to investigate the effects of the pandemic and capture modifications, prompted by pandemic-related control measures, on cervical cancer screening-related activities from mid-March to mid-August 2020, across Canada.

Methods: The survey consisted of 61 questions related to the continuum of care in cervical cancer screening and treatment: appointment scheduling, tests, colposcopy, follow-up, treatment of pre-cancerous lesions/cancer, and telemedicine. We piloted the survey with 21 Canadian experts in cervical cancer prevention and care. We partnered with the Society of Canadian Colposcopists, Society of Gynecologic Oncology of Canada, Canadian Association of Pathologists, and Society of Obstetricians and Gynecologists of Canada, which distributed the survey to their members via email. We reached out to family physicians and nurse practitioners via MDBriefCase. The survey was also posted on McGill Channels (Department of Family Medicine News and Events) and social media platforms. The data were analyzed descriptively.

Results: Unique responses were collected from 510 participants (16 November 2020 - 28 February 2021), representing 418 fully- and 92 partially- completed surveys. Responses were from Ontario (41.0%), British Columbia (21.0%), and Alberta (12.8%), and mostly comprised family physicians/general practitioners (43.7%), and gynecologist/obstetrician professionals (21.6%). Cancelled screening appointments were mainly reported by family physicians/general practitioners (28.3%), followed by gynecologist/obstetrician professionals (19.8%), and primarily occurred in private clinics (30.5%). Decreases in the number of screening Pap tests and colposcopy procedures were consistently observed across Canadian provinces. About 90% reported that their practice/institution adopted telemedicine to communicate with patients.

Conclusions: The area most severely impacted by the pandemic was appointment scheduling, with an important level of cancellations reported. Survey results may inform resumptions of various fronts in cervical cancer screening and management.

Funding: The present work was supported by the Canadian Institutes of Health Research (operating grant COVID-19 May 2020 Rapid Research Funding Opportunity VR5-172666 Rapid Research competition and foundation grant 143347 to Eduardo L. Franco). Eliya Farah and Rami Ali each received a MSc. stipend from the Department of Oncology, McGill University.

Efficacy and safety of a self-applied carrageenan-based gel to prevent human papillomavirus infection in sexually active young women (CATCH study): an exploratory phase IIB randomised, placebo-controlled trial

Background

Carrageenan demonstrated potent anti-HPV (human papillomavirus) activity in vitro and in animal models. The Carrageenan-gel Against Transmission of Cervical Human papillomavirus trial's interim analysis (n = 277) demonstrated a 36% protective effect of carrageenan against incident HPV infections. Herein, we report the trial's final results.

Methods

In this exploratory phase IIB randomised, placebo-controlled trial, we recruited healthy women aged ≥18 years primarily from health service clinics at two Canadian Universities in Montreal. Participants were randomised (1:1) by the study coordinator (using computer-assisted block randomisation with randomly variable block sizes up to a block size of eight) to a carrageenan-based or placebo gel to be self-applied every other day for the first month and before/after intercourse. Participants, study nurses, and laboratory technicians (HPV testing and genotyping) were blinded to group assignment. At each visit (months 0, 0.5, 1, 3, 6, 9, 12), participants provided questionnaire data and a self-collected vaginal sample (tested for 36 HPV types, Linear Array). The primary outcome was type-specific HPV incidence (occurring at any follow-up visit). Intention-to-treat analyses for incidence were conducted using Cox proportional hazards regression models, including participants with ≥2 visits. Safety analyses included all participants randomised. This trial is registered with the ISRCTN registry, ISRCTN96104919.

Findings

Between Jan 16, 2013 and Sept 30, 2020, 461 participants (enrolled) were randomly assigned to the carrageenan (n = 227) or placebo (n = 234) groups. Incidence and safety analyses included 429 and 461 participants, respectively. We found 51.9% (108/208) of participants in carrageenan and 66.5% (147/221) in placebo arm acquired ≥1 HPV type (hazard ratio 0.63 [95% CI: 0.49-0.81], p = 0.0003). Adverse events were reported by 34.8% (79/227) and 39.7% (93/234) of participants in carrageenan and placebo arm (p = 0.27), respectively.

Interpretation

Consistent with the interim analysis, use of a carrageenan-based gel compared to placebo resulted in a 37% reduction in risk of incident genital HPV infections in women with no increase in adverse events. A carrageenan-based gel may complement HPV vaccination.

Funding

Canadian Institutes of Health Research, CarraShield Labs Inc.

Serologic Response to Human Papillomavirus Genotypes Among Unvaccinated Women: Findings From the HITCH Cohort Study

BACKGROUND

Humoral immune responses may be critical for preventing, controlling, and/or eliminating human papillomavirus (HPV) infection. We analyzed humoral response to natural HPV infection considering phylogenetic relatedness among unvaccinated women.

METHODS

We included 399 young women attending university/college in Montreal, Canada who were participants of the HITCH cohort. Participants provided blood samples at baseline and 5 follow-up visits. Antibody response to bacterially expressed L1 and E6 glutathione S-transferase (GST) fusion proteins, and virus-like particles (VLP-L1) of Alphapapillomavirus types were measured using multiplex serology. We assessed correlations and associations between HPV types at baseline using Pearson correlation coefficients (r) and univariable linear regressions.

RESULTS

At baseline, > 40% were seropositive for GST-L1 antibodies of at least 1 HPV type. Strong correlations between GST-L1 were observed for α9 HPV types: 58-52 (r = 0.86), 58-33 (r = 0.75), 33-52 (r = 0.72), and between GST-E6: 52-11 (r = 0.84), 52-18 (r = 0.79), 58-33 (r = 0.78), 35-11 (r = 0.76). HPV16 VLP-L1 moderately explained variability in HPV16 GST-L1 (regression coefficient [b] = 0.38, R2 = 43.1%), and HPV45 GST-L1 in HPV18 GST-L1 (b = 0.68, R2 = 42.8%). GST-E6 antibodies accounted for a low to moderate proportion of variability in HPV16 and HPV18 GST-E6 (R2 = 6.4%-62.2%).

CONCLUSIONS

Associations between naturally induced HPV-specific antibodies depend on phylogenetic relatedness.

Association between male circumcision and human papillomavirus infection in males and females: a systematic review, meta-analysis, and meta-regression

BACKGROUND

Previous studies have suggested a protective effect of male circumcision on human papillomavirus (HPV) infections in males, and that this protection may be conferred to their female sexual partners.

OBJECTIVES

To synthesize the available evidence on the association between male circumcision and HPV infections in males and females.

DATA SOURCES

We searched MEDLINE, Embase, Scopus, Cochrane, LILACS, and ProQuest Dissertations & Theses Global for records published up to 22 June 2022.

STUDY ELIGIBILITY

We considered observational and experimental studies that assessed male circumcision status and HPV prevalence, incidence, or clearance in males or females for inclusion.

PARTICIPANTS

Males and their female sexual partners who were tested for genital HPV infection.

INTERVENTIONS

Male circumcision compared to no circumcision.

RISK OF BIAS ASSESSMENT

The Newcastle-Ottawa scale was used for observational studies and the Cochrane risk-of-bias tool was used for randomized trials.

DATA SYNTHESIS

We estimated summary measures of effect and 95% confidence intervals (CI) for the prevalence, incidence, and clearance of HPV infections in males and females using random-effects meta-analysis. We assessed effect modification of circumcision on HPV prevalence by penile site in males using random-effects meta-regression.

RESULTS

Across 32 studies, male circumcision was associated with decreased odds of prevalent HPV infections (OR 0.45, CI 0.34-0.61), a reduced incidence rate of HPV infections (IRR 0.69, CI 0.57-0.83), and an increased risk of clearing HPV infections (RR 1.44, CI 1.28-1.61) at the glans penis among male subjects. Circumcision conferred greater protection against infection at the glans than shaft (OR 0.68, 95% CI 0.48-0.98). Females with circumcised partners were protected from all outcomes.

CONCLUSIONS

Male circumcision may protect against various HPV infection outcomes, suggesting its prophylactic potential. Understanding site-specific effects of circumcision on HPV infection prevalence has important implications for studies of HPV transmission.

Detection and clearance of type-specific and phylogenetically related genital human papillomavirus infections in young women in new heterosexual relationships

Background

Understanding the natural history of human papillomavirus (HPV) infections is essential to effective cervical cancer prevention planning. We examined these outcomes in-depth among young women.

Methods

The HPV Infection and Transmission among Couples through Heterosexual Activity (HITCH) study is a prospective cohort of 501 college-age women who recently initiated a heterosexual relationship. We tested vaginal samples collected at six clinical visits over 24 months for 36 HPV types. Using rates and Kaplan-Meier analysis, we estimated time-to-event statistics with 95% confidence intervals (CIs) for detection of incident infections and liberal clearance of incident and present-at-baseline infections (separately). We conducted analyses at the woman- and HPV-levels, with HPV types grouped by phylogenetic relatedness.

Results

By 24 months, we detected incident infections in 40.4%, CI:33.4-48.4 of women. Incident subgenus 1 (43.4, CI:33.6-56.4), 2 (47.1, CI:39.9-55.5) and 3 (46.6, CI:37.7-57.7) infections cleared at similar rates per 1000 infection-months. We observed similar homogeny in HPV-level clearance rates among present-at-baseline infections.

Conclusions

Our woman-level analyses of infection detection and clearance agreed with similar studies. However, our HPV-level analyses did not clearly indicate that high oncogenic risk subgenus 2 infections take longer to clear than their low oncogenic risk and commensal subgenera 1 and 3 counterparts.

Site-specific cancer incidence by race and immigration status in Canada 2006-2015: a population-based data linkage study

BACKGROUND

The Canadian Cancer Registry does not collect demographic data beyond age and sex, making it difficult to monitor health inequalities. Using data linkage, we compared site-specific cancer incidence rates by race.

METHODS

The 2006 and 2011 Canadian Census Health and Environment Cohorts are population-based probabilistically linked datasets of 5.9 million respondents of the 2006 long-form census and 6.5 million respondents of the 2011 National Household Survey. Race was self-reported. Respondent data were linked with the Canadian Cancer Registry up to 2015. We calculated age-standardized incidence rate ratios (ASIRR), comparing group-specific rates to the overall population rate with bootstrapped 95% confidence intervals (95%CI). We used negative binomial regressions to adjust for socioeconomic variables and assess interactions with immigration status.

RESULTS

The age-standardized overall cancer incidence rate was lower in almost all non-White racial groups than in the overall population, except for White and Indigenous peoples who had higher incidence rates than the overall population (ASIRRs 1.03-1.04). Immigrants had substantially lower age-standardized overall cancer incidence rates than non-immigrants (ASIRR 0.83, 95%CI 0.82-0.84). Stomach, liver, and thyroid cancers and multiple myelomas were the sites where non-White racial groups had consistently higher site-specific cancer incidence rates than the overall population. Immigration status was an important modifier of cancer risk in the interaction model.

CONCLUSIONS

Differences in cancer incidence between racial groups are likely influenced by differences in lifestyles, early life exposures, and selection factors for immigration.

IMPACT

Data linkage can help monitor health inequalities and assess progress in preventive interventions against cancer.

The impact of lag time to cancer diagnosis and treatment on clinical outcomes prior to the COVID-19 pandemic: A scoping review of systematic reviews and meta-analyses

Background

The COVID-19 pandemic has disrupted cancer care, raising concerns regarding the impact of wait time, or 'lag time', on clinical outcomes. We aimed to contextualize pandemic-related lag times by mapping pre-pandemic evidence from systematic reviews and/or meta-analyses on the association between lag time to cancer diagnosis and treatment with mortality- and morbidity-related outcomes.

Methods

We systematically searched MEDLINE, EMBASE, Web of Science, and Cochrane Library of Systematic Reviews for reviews published prior to the pandemic (1 January 2010-31 December 2019). We extracted data on methodological characteristics, lag time interval start and endpoints, qualitative findings from systematic reviews, and pooled risk estimates of mortality- (i.e., overall survival) and morbidity- (i.e., local regional control) related outcomes from meta-analyses. We categorized lag times according to milestones across the cancer care continuum and summarized outcomes by cancer site and lag time interval.

Results

We identified 9032 records through database searches, of which 29 were eligible. We classified 33 unique types of lag time intervals across 10 cancer sites, of which breast, colorectal, head and neck, and ovarian cancers were investigated most. Two systematic reviews investigating lag time to diagnosis reported different findings regarding survival outcomes among paediatric patients with Ewing's sarcomas or central nervous system tumours. Comparable risk estimates of mortality were found for lag time intervals from surgery to adjuvant chemotherapy for breast, colorectal, and ovarian cancers. Risk estimates of pathologic complete response indicated an optimal time window of 7-8 weeks for neoadjuvant chemotherapy completion prior to surgery for rectal cancers. In comparing methods across meta-analyses on the same cancer sites, lag times, and outcomes, we identified critical variations in lag time research design.

Conclusions

Our review highlighted measured associations between lag time and cancer-related outcomes and identified the need for a standardized methodological approach in areas such as lag time definitions and accounting for the waiting-time paradox. Prioritization of lag time research is integral for revised cancer care guidelines under pandemic contingency and assessing the pandemic's long-term effect on patients with cancer.

Funding

The present work was supported by the Canadian Institutes of Health Research (CIHR-COVID-19 Rapid Research Funding opportunity, VR5-172666 grant to Eduardo L. Franco). Parker Tope, Eliya Farah, and Rami Ali each received an MSc. stipend from the Gerald Bronfman Department of Oncology, McGill University.

Association Between Human Leukocyte Antigen Polymorphism and Human Papillomavirus Infection in Brazilian Women

Background:

Human papillomavirus (HPV) infection is a necessary cause for cervical cancer, but the majority of genital HPV infections clear spontaneously. Human leukocyte antigen (HLA) polymorphism influences immune response and genetic susceptibility, and its association with cervical cancer was extensively investigated, but few reports focused on HPV infection.

Methods:

We performed molecular typing of HLA-A , -B , -DQB1, and -DRB1 genes as well as of HPV in 1226 women enrolled in the Ludwig-McGill cohort study and investigated the influence on cumulative HPV positivity. HPV types were grouped according to Alphapapillomavirus subgenera that exhibit similar tissue tropism and biological behavior concerning cancer risk. The associations between HLA polymorphisms and HPV infections were estimated using unconditional logistic regression analysis adjusted for age and race.

Results:

HLA-B *08 and HLA-DRB1 *15:01 were negatively associated with HPV positivity, and similar effects were observed for HPV Subgenus 2 only, which includes HPV16. HLA-DRB1* 08:07 was associated with overall HPV infection and Subgenus 2 positivity. The haplotypes HLA-B *08-DRB1 *03:01-DQB1 *02:01 and HLA-DRB1 *08:07-DQB1 *04:02 were negatively and positively associated with cumulative HPV positivity, respectively.

Conclusions:

Our data suggest that HLA class I and II polymorphism can influence HPV natural infection.

A prospective study of human papillomavirus infections and risk of cervical neoplasia in Brazilian women found that human leukocyte antigen polymorphisms may influence the natural history of these infections.

Male Circumcision and Genital Human Papillomavirus (HPV) Infection in Males and Their Female Sexual Partners: Findings From the HPV Infection and Transmission Among Couples Through Heterosexual Activity (HITCH) Cohort Study

BACKGROUND

Previous studies examining the association between male circumcision (MC) and human papillomavirus (HPV) infections have reported inconsistent results. We used data from the HPV Infection and Transmission Among Couples Through Heterosexual Activity (HITCH) cohort study to examine the association between MC and HPV infections in males and their female sexual partners.

METHODS

We enrolled monogamous couples in a longitudinal study between 2005 and 2011 in Montreal, Canada. We used logistic and Poisson regression models with propensity score adjustment to estimate odds ratios (ORs) and rate ratios for the association between MC and the prevalence, transmission, and clearance of HPV infections.

RESULTS

Four hundred thirteen couples were included in our study. The prevalence OR for the association between MC and baseline infections was 0.81 (95% confidence interval [CI], .56-1.16) in males and 1.05 (95% CI, .75-1.46) in females. The incidence rate ratio for infection transmission was 0.59 (95% CI, .16-2.20) for male-to-female transmission and 0.77 (95% CI, .37-1.60) for female-to-male transmission. The clearance rate ratio for clearance of infections was 0.81 (95% CI, .52-1.24).

CONCLUSIONS

We found little evidence of an association between MC and HPV infection prevalence, transmission, or clearance in males and females. Further longitudinal couple-based studies are required to investigate this association.

Ecological analysis of correlates of cervical cancer morbidity and mortality in Sub-Saharan Africa

BACKGROUND

Cervical cancer is the fourth leading cause of death among women worldwide, with 85% of the burden falling on low- to middle- income countries. We studied the correlates of cervical cancer incidence and mortality, and case-fatality in Sub-Saharan Africa.

METHODS

Country-level data on 16 putative cervical cancer correlates for 37 Sub-Saharan African countries were collected from publicly available data sources. We performed univariate and multiple (stepwise) linear regression analyses to identify correlates of cervical cancer incidence and mortality, and case-fatality.

RESULTS

In univariate analyses, incidence and mortality rates were significantly correlated with contraceptive use, penile cancer incidence, and human immunodeficiency virus prevalence. Incidence rates were also correlated with literacy rates, whereas mortality rates were correlated with the proportion of rural population and screening coverage. Multiple regression analyses showed contraceptive use (p=0.009) and penile cancer incidence (p=0.004) as associated with cervical cancer incidence. Penile cancer incidence (p=9.77 x 10-5) and number of medical doctors (p=0.0433) were associated with mortality. The goodness of fit of the incidence and mortality models was moderate at best, explaining 49% and 37% of variability in the data, respectively. However, the case-fatality model had the best fit explaining most of the variation (adjusted R2=0.948; p=6.822 x 10-16).

CONCLUSIONS

To reduce the burden of cervical cancer in Sub-Saharan Africa, it would be important to design multimodal interventions that not only target screening and HPV vaccination, but also focus on cervical cancer correlates.

IMPACT

Identifying contextual factors associated with cervical cancer in this region could inform targeted interventions.

Protection to Self and to One's Sexual Partner After Human Papillomavirus Vaccination: Preliminary Analysis From the Transmission Reduction And Prevention with HPV Vaccination Study

BACKGROUND

It is unknown whether recently human papillomavirus (HPV)-vaccinated individuals confer protection against vaccine-preventable HPV types to their partners.

METHODS

Participants 18 to 45 years old who were living in Montreal, Canada, and in a heterosexual relationship of 6 months or less were randomly assigned to receive the intervention HPV vaccine, Gardasil or Gardasil 9, or active control (AC), Avaxim, a hepatitis A vaccine. Couples attended a maximum of 6 clinic visits (baseline and at 2, 4, 6, 9, and 12 months) and provided genital samples for detection of 36 HPV genotypes. Participants were vaccinated at baseline and at 2 and 6 months. We used Cox proportional hazards regression models to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for associations between the administered vaccine and infections at the HPV episode level.

RESULTS

We restricted analyses to 273 participants (intervention: n = 141, AC: n = 132) who had at least 2 visits with valid HPV data. The HR of becoming positive for a given vaccine-preventable HPV type in the intervention group among those who received at least 1 dose compared with AC was 0.47 (95% CI, 0.23-0.97). Comparing individuals with HPV-vaccinated versus AC-vaccinated partners, there was no difference in risk of becoming positive for a given vaccine-preventable HPV type among those whose partners received at least 1 (HR, 1.46; 95% CI, 0.73-2.94) or 2 (HR, 0.78; 95% CI, 0.31-1.96) doses.

CONCLUSIONS

Our study provides inconclusive evidence that individuals whose partner recently received an HPV vaccine are protected from vaccine-preventable types but demonstrates that vaccinated individuals are at a lower risk of incident infections.Trial Registration Number: NCT01824537.

Role of Human Leukocyte Antigen Allele Sharing in Human Papillomavirus Infection Transmission Among Heterosexual Couples: Findings From the Hitch Cohort Study

Background

Human leukocyte antigen (HLA) polymorphism influences innate and adaptive immune responses. Among heterosexual couples in the HPV Infection and Transmission Among Couples Through Heterosexual Activity (HITCH) cohort study, we examined whether allele sharing in a couple predicted the partners’ infections with the same human papillomavirus (HPV) type.

Methods

We tested genital samples from 271 couples for 36 HPV genotypes by polymerase chain reaction. We used direct DNA sequencing to type HLA-B07, -DRB1, -DQB1 and -G. Generalized estimating equations were used to examine the associations between the extent of allele sharing and HPV type concordance in which at least 1 of the partners was HPV positive.

Results

We identified 106 different HLA alleles. The most common HLA alleles among couples were G*01:01:01 (95.6%), G*01:01:02 (60.1%), DQB1*03:01 (57.2%), and DRB1*07:01 (46.9%). Allele sharing was as follows: 19.6% shared none, 43.2% shared 1 only, 25.1% shared 2, and 12.5% shared 3–5. Irrespective of HLA class, grouped or in combination, the extent of allele sharing was not a significant predictor of type-specific HPV concordance in a couple (odds ratio, 1.1 [95% confidence interval, .5–2.1], for 3–5 vs none).

Conclusions

We found no evidence that the extent of HLA allele concordance influences the likelihood of HPV transmission in newly formed heterosexual couples.

A review of ethical and legal aspects of gender-neutral human papillomavirus vaccination

While launching a campaign to eliminate cervical cancer, the World Health Organization called to halt human papillomavirus (HPV) gender-neutral vaccination (GNV) because of limited vaccine supply, raising ethical and legal questions about female-only vaccination versus GNV. We identified ethical and legal aspects of HPV GNV by searching MEDLINE for records up to February 19, 2021. We also provided an overview of HPV vaccines, the evolution of HPV vaccine recommendations in North America, and a timeline of male HPV vaccination introduction by searching PubMed, Google, and government websites. Four HPV vaccines are available: Cervarix®, Gardasil®, Gardasil®9, and Cecolin®. Vaccine recommendations in North America evolved from female only to eventually include males. Following the Food and Drug Administration's approval of the first HPV vaccine for males (2009), 35 countries began vaccinating males (2011-2020). Based on 56 eligible records out of 652, we identified the following constructs: lower male awareness of HPV and vaccination (n=13), limited economic resources (n=5), shared social responsibility (n=18), unprotected groups from female-only HPV vaccination (n=10), limited screening for HPV-associated noncervical cancers (n=6), consideration of ethical principles (n=17), and HPV vaccine mandates (n=5). Ethical and legal aspects must be considered when recommending vaccination for females only or GNV.

Efficacy of a Carrageenan Gel in Increasing Clearance of Anal Human Papillomavirus Infections in Men: Interim Analysis of a Double-Blind, Randomized Controlled Trial

Preclinical studies have demonstrated carrageenan's anti-human papillomavirus (HPV) activity. We assessed efficacy of a carrageenan-based gel compared to a placebo gel in increasing the clearance of anal HPV infections among gay, bisexual, and other men who have sex with men (gbMSM). Of 255 enrolled gbMSM, 134 were HPV positive at baseline and had valid HPV results for ≥2 visits. Carrageenan did not differ from placebo in clearing all baseline infections (hazard ratio, 0.84 [95% confidence interval, .31-2.27]), based on having 2 consecutive HPV-negative visits following at least 1 HPV-positive visit. There were no remarkable differences for analyses at the HPV type level or by human immunodeficiency virus status.

CLINICAL TRIALS REGISTRATION

NCT02354144.

Proportion of incident genital human papillomavirus detections not attributable to transmission and potentially attributable to latent infections: Implications for cervical cancer screening

BACKGROUND

Infections with human papillomaviruses (HPV) may enter a latent state, and eventually become reactivated following loss of immune control. It is unclear what proportion of incident HPV detections are reactivations of previous latent infections versus new transmissions.

METHODS

The HITCH cohort study prospectively followed young newly-formed heterosexual partners recruited between 2005-2011 in Montréal, Canada. We calculated the fraction of incident HPV detections non-attributable to sexual transmission risk factors with a Bayesian Markov model. Results are the median (2.5-97.5 th percentiles) of the estimated posterior distribution.

RESULTS

544 type-specific incident HPV detection events occurred in 849 participants; 33% of incident HPV detections occurred in participants whose HITCH partners were negative for that HPV type and who reported no other sex partners over follow-up. We estimate that 43% (38-48%) of all incident HPV detections in this population were not attributable to recent sexual transmission and might be potentially reactivation of latent infections.

CONCLUSIONS

A positive HPV test result in many cases may be a reactivated past infection, rather than a new infection from recent sexual behaviors or partner infidelity. The potential for reactivation of latent infections in previously HPV-negative women should be considered in the context of cervical cancer screening.

Vaginal microbiome components as correlates of cervical human papillomavirus infection

BACKGROUND

The interplay between vaginal microbiome and human papillomavirus (HPV) remains unclear, partly due to heterogeneity of the microbiota.

METHODS

We used data from 546 women enrolled in a cross-sectional study conducted in five Brazilian regions. We genotyped vaginal samples for HPV and sequenced V3-V4 region of 16S rRNA gene for vaginal microbiome analysis. We used stepwise logistic regression to construct two linear scores to predict high-risk HPV (hrHPV) positivity: one based exclusively on presence of individual bacterial taxa (microbiome-based [MB] score) and the other exclusively on participants' sociodemographic, behavioral and clinical (SBC) characteristics. The MB score combined coefficients of 30 (out of 116) species. The SBC score retained six out of 25 candidate variables. We constructed receiver operating characteristic curves for the scores as hrHPV correlates and compared areas under the curve (AUC) and 95% confidence intervals (CI).

RESULTS

Overall, prevalence of hrHPV was 15.8%, and 26.2% had a Lactobacillus-depleted microbiome. The AUCs were 0.8022 (CI:0.7517-0.8527) for MB score and 0.7027 (CI:0.6419-0.7636) for SBC score (P=0.0163).

CONCLUSIONS

The proposed MB score is strongly correlated with hrHPV positivity - exceeding the predictive value of behavioral variables - suggesting its potential as an indicator of infection and possible value for clinical risk stratification.

Is Hodgkin Lymphoma Associated with Hepatitis B and C Viruses? A Systematic Review and Meta-analysis

BACKGROUND

Apart from the Epstein-Barr virus (EBV), the etiology of the hematologic malignancy Hodgkin lymphoma (HL) is not well defined. Hepatitis B virus (HBV) and hepatitis C virus (HCV) are associated with some lymphoproliferative diseases with similarities to HL.

METHODS

We performed a systematic review and meta-analysis, by searching Embase, MEDLINE, and Web of Science databases on March 9, 2021, for studies reporting a measure of association for HBV and HL or HCV and HL. We calculated pooled relative risks (RR) and their 95% confidence intervals (CI).

RESULTS

Pooling nine HBV studies with 1,762 HL cases yielded an RR of 1.39 (95% CI, 1.00-1.94) and pooling 15 HCV studies with 4,837 HL cases resulted in an RR of 1.09 (95% CI, 0.88-1.35). Meta-analyzing by study design, hepatitis detection method, and region revealed two subgroups with statistically significant associations-HCV studies that used hospital-based controls and/or were conducted in the West Pacific. No included study assessed age or EBV tumor status in relation to HL.

CONCLUSIONS

Although we did not find an association between HBV or HCV and HL, research assessing the impact of age and EBV tumor status was lacking.

IMPACT

The effect of HBV or HCV infection in the development of HL remains unclear.

Design and methods for the Carrageenan-gel Against Transmission of Cervical Human papillomavirus (CATCH) study: A randomized controlled trial

Human papillomavirus (HPV) infection, a common sexually transmitted infection, is causally associated with cervical cancer. Vaccination against HPV provides protection; however, HPV vaccines are exclusively prophylactic. Carrageenan, an extract from red algae, demonstrated potent anti-HPV activity in in vitro and animal studies. We describe the protocol for the Carrageenan-gel Against Transmission of Cervical Human papillomavirus (CATCH) study, an ongoing randomized controlled trial among sexually active young females, aimed at evaluating the efficacy of a carrageenan-based gel in reducing type-specific incidence (i.e. new detections of HPV) and prevalence (i.e. absence of a previously detected HPV) of genital HPV infections as well as participant adherence to the intervention. The CATCH study is a phase IIB double-blind randomized placebo-controlled trial. Eligible women 18 years and older are randomized 1:1 to the carrageenan-containing gel or placebo gel arm. For the first month, participants use the study gel intra-vaginally every other day, and over the 12-month study period, prior to and after each act of vaginal intercourse. At each study visit (months 0, 0.5, 1, 3, 6, 9, 12), participants provide a self-collected vaginal sample and record information on sexual activities, adherence, and adverse events using a computerized questionnaire. The primary outcomes are incident and prevalent type-specific cervicovaginal HPV infection. The primary analyses are based on intention-to-treat whereas per-protocol analyses are conducted based on measures of adherence. Trial registration: ISRCTN96104919.

Association of Serum 25-Hydroxyvitamin D With Prevalence, Incidence, and Clearance of Vaginal HPV Infection in Young Women

BACKGROUND

We assessed the association between serum 25-hydroxyvitamin D levels and genital human papillomavirus (HPV) prevalence, incidence, and clearance among female participants in the HPV Infection and Transmission among Couples through Heterosexual activity (HITCH) Cohort Study.

METHODS

We genotyped HPV DNA in vaginal samples and quantified baseline serum 25-hydroxyvitamin D levels using Roche's Linear Array and Total vitamin D assay, respectively. We used logistic and Cox proportional hazards models, respectively, to estimate adjusted odds ratios (ORs) and hazard ratios (HRs) with 95% confidence intervals (CIs).

RESULTS

There was no association between vitamin D levels (every 10-ng/mL increase) at baseline and HPV prevalence (OR, 0.88; 95% CI, .73-1.03) or incidence (HR, 0.88; 95% CI, .73-1.06), but we observed a modest negative association with HPV clearance (HR, 0.76; 95% CI, .60-.96). Vitamin D levels <30 ng/mL, compared with those ≥30 ng/mL, were not associated with HPV prevalence (OR, 0.98; 95% CI, .57-1.69) or incidence (HR, .87; 95% CI, .50-1.43), but they were associated with a marginally significant increased clearance (OR, 2.14; 95% CI, .99-4.64). We observed consistent results with restricted cubic spline modeling of vitamin D levels and clinically defined categories. HPV type-specific analyses accounting for multiple HPV infections per participant showed no association between vitamin D levels and all study outcomes.

CONCLUSIONS

This study provided no evidence of an association between low vitamin D levels and increased HPV prevalence, acquisition, or clearance.

Carrageenan as a Preventive Agent Against Human Papillomavirus Infection: A Narrative Review

ABSTRACT

Carrageenan, an extract from red algae, was identified over a decade ago as a potent inhibitor of human papillomavirus (HPV) infection in vitro. After this discovery, several studies evaluated carrageenan's anti-HPV activity in cells, experimental animals, and humans. We reviewed the evidence for carrageenan's anti-HPV activity. Studies had to be in vitro, in vivo, or in humans and report on carrageenan's anti-HPV activity. Of the 39 records identified in PubMed and 29 records in Clinicaltrials.gov, 22 records were included after screening: 8 in vitro (including 2 ex vivo), 3 in vivo, 5 in vitro and in vivo, 3 clinical studies, and 3 trial protocols. A total of 12 studies evaluated carrageenan exclusively, whereas 7 considered carrageenan combined with additional antiviral or other agents. One study protocol will evaluate carrageenan exclusively, and 2 others will evaluate carrageenan-combination products. Most clinical studies evaluated carrageenan's ability to prevent HPV acquisition (n = 4), whereas one study explored its ability to promote clearance of existing infection (defined as the absence of HPV DNA detection). Carrageenan's anti-HPV activity was observed consistently across study designs, except in 2 studies: 1 in vitro study where 2 of the HPV types tested were not significantly inhibited by carrageenan and 1 phase IIB trial in gay, bisexual, and other men who have sex with men. This review supports the premise that carrageenan, alone or in combination with other antiviral agents, might be a potential prevention strategy complementary to HPV vaccination for women.

Efficacy of a carrageenan gel in preventing anal human papillomavirus (HPV) infection: interim analysis of the Lubricant Investigation in Men to Inhibit Transmission of HPV Infection (LIMIT-HPV) randomised controlled trial

BACKGROUND

Carrageenan, a non-toxic gelling agent derived from red algae, has potent anti-human papillomavirus (HPV) activity in in vitro and animal studies. We assessed, in an interim analysis, the efficacy of a carrageenan-based gel in reducing the risk of new detections of anal HPV among gay, bisexual and other men who have sex with men (gbMSM).

METHODS

The LIMIT-HPV study (Lubricant Investigation in Men to Inhibit Transmission of HPV Infection) is a phase IIb, double-blind, placebo-controlled randomised controlled trial conducted in Montreal, Canada. gbMSM were randomly assigned (1:1) to receive a carrageenan-based or placebo gel. Participants were instructed to apply the gel to the anus, condom and/or partners' penis before and-as required-during receptive anal intercourse. Questionnaire data and anal samples were collected at 0, 1, 2, 3, 6, 9 and 12 months. We estimated new detections of anal HPV infection(s) detected via Linear Array using Cox proportional hazards models.

RESULTS

Participants recruited from February 2016 to December 2019 were randomly assigned to the carrageenan (n=127) or placebo (n=128) arm. The efficacy and safety analyses included 201 and 210 participants. The median follow-up time was 7.6 months (range: 0-28.5) in the carrageenan group and 9.3 months (range: 0-40.7) in the placebo group. The HR for new detections was 1.21 (95% CI 0.86 to 1.70): 69.4% and 65.1% new detections of HPV in the carrageenan and placebo arms, respectively. More adverse events were reported in the carrageenan (59.8%) compared with the placebo (39.8%) arm.

CONCLUSIONS

The interim analysis did not demonstrate a protective effect of carrageenan on the risk of new detections of anal HPV infection among gbMSM. Carrageenan gel use was associated with a higher proportion of adverse events. Given these findings and the (assumed) low probability that a beneficial effect would be found by the study's end, the trial was terminated as recommended by the Data Safety and Monitoring Board.

TRIAL REGISTRATION NUMBER

NCT02354144.

Sex- and Type-specific Genital Human Papillomavirus Transmission Rates Between Heterosexual Partners: A Bayesian Reanalysis of the HITCH Cohort

BACKGROUND

It is unclear whether sexual transmission rates of human papillomaviruses (HPV) differ between sexes and HPV types. We estimate updated transmission rates from the final HITCH cohort study and propose an estimation method that accounts for interval-censored data and infection clearance.

METHODS

We enrolled young women 18-24 years old and their male sex partners ≥18 years old in Montréal, Canada, between 2005 and 2011. We followed women over 24 months and men over 4 months. We tested genital samples with Linear Array for HPV DNA detection and genotyping. We calculated infection transmission rates between partners using a multistate Markov model via a Bayesian approach. We report the posterior median and 2.5%-97.5% percentile intervals (95% PI).

RESULTS

We observed 166 type-specific incident HPV transmission events in 447 women and 402 men. The estimated median transmission rate from an HPV-positive to a negative partner was 4.2 (95% PI = 3.1 to 5.3) per 100 person-months. The transmission rate from men-to-women was 3.5 (95% PI = 2.5 to 4.7) and from women-to-men was 5.6 (95% PI = 3.8 to 7.0) per 100 person-months, corresponding to a rate ratio of 1.6 (95% PI = 1.0 to 2.5). Partners reporting always using condoms had a 0.22 (95% PI = 0.05 to 0.61) times lower HPV transmission rate than those reporting never using condoms. HPV16/18 did not have particularly high transmission rates relative to other HPV types.

CONCLUSION

Our updated analysis supports previous research suggesting higher women-to-men than men-to-women HPV transmission rates and a protective effect of condoms in heterosexual partnerships. Our results also suggest that crude incidence rates underestimate HPV transmission rates due to interval-censoring. See video abstract at http://links.lww.com/EDE/B794.

Assessment of the possible inhibitory effect of carrageenan in human papillomavirus DNA testing by polymerase chain reaction amplification

We assessed carrageenan's potential to inhibit human papillomavirus (HPV) DNA extraction and amplification in vaginal swab samples collected in a trial, assessing the efficacy of a carrageenan-based gel against HPV infections. Experiment #1 consisted of adding gel (carrageenan-containing or placebo) to swabs and comparing HPV DNA detection by polymerase chain reaction (PCR) to unmanipulated samples collected from the same participants. For Experiments #2 and #3, we tested vaginal samples for inhibition by addition of an internal control and amplification by real-time PCR. Experiment #4 investigated carrageenan's interference with the extraction process by assessing HPV45 detectability in undiluted and diluted HPV45 positive samples (n = 3) with carrageenan versus no gel. In Experiment #1, there was a loss of HPV positivity with the addition of carrageenan (n = 9), but none with placebo gel (n = 5). In Experiments #2 and #3, the absence of the amplified product was observed in samples from the carrageenan arm: 3.3% (1/30) and 0.5% (1/199) of samples. In Experiment #4, HPV45 was not detected in undiluted carrageenan-containing samples, but after 1/50 dilution, the same HPV45 copy number was detected. Carrageenan does not affect the DNA extraction process, and inhibition of HPV DNA amplification by carrageenan occurs infrequently.

Directionality of Genital Human Papillomavirus Infection Transmission Within Heterosexual Couples: A Systematic Review and Meta-analysis

BACKGROUND

Limited evidence indicates greater female-to-male (F-M) transmission of genital infection with human papillomavirus (HPV) relative to male-to-female (M-F). We verified the hypothesis of a differential transmission rate in couple-based studies by conducting a systematic review and meta-analysis.

METHODS

We searched MEDLINE, EMBASE, Scopus, and Cochrane Library databases for studies published until December 2019. We calculated pooled estimates of F-M and M-F transmission rates and their rate differences per 100 person-months, with 95% confidence intervals (CI), using a random-effects model. We counted occurrences of directionality preponderance for each HPV type.

RESULTS

We identified 7 eligible studies published between 2008 and 2019, providing data for 752 couples. Pooled estimates for F-M and M-F transmission rates were 3.01 (95% CI, 1.19-7.64; I2 = 97%) and 1.60 (95% CI, 0.86-2.98; I2 = 89%), respectively. The overall rate difference was 0.61 (95% CI, -0.27 to 1.49; I2 = 75%). Three studies provided rates by sex and HPV genotype; 2 favored a preponderance of F-M and 1 favored M-F transmission.

CONCLUSIONS

There was slight evidence for a differential transmission rate favoring higher F-M than M-F transmission with substantial statistical heterogeneity across studies.

A Review of Canadian Cancer-Related Clinical Practice Guidelines and Resources during the COVID-19 Pandemic

(1) Background: Preventive measures taken in response to the coronavirus disease 2019 (COVID-19) pandemic have adversely affected an entire range of cancer-related medical activities. The reallocation of medical resources, staff, and ambulatory services, as well as critical shortages in pharmaceutical and medical supplies have compelled healthcare professionals to prioritize patients with cancer to treatment and screening services based on a set of classification criteria in cancer-related guidelines. Cancer patients themselves have been affected on multiple levels, and addressing their concerns poses another challenge to the oncology community. (2) Methods: We conducted a Canada-wide search of cancer-related clinical practice guidelines on the management and prioritization of individuals into treatment and screening services. We also outlined the resources provided by Canadian cancer charities and patient advocacy groups to provide cancer patients, or potential cancer patients, with useful information and valuable support resources. (3) Results: The identified provincial guidelines emphasized cancer care (i.e., treatment) more than cancer control (i.e., screening). For cancer-related resources, a clear significance was placed on knowledge & awareness and supportive resources, mainly relating to mental health. (4) Conclusion: We provided a guidance document outlining cancer-related guidelines and resources that are available to healthcare providers and patients across Canada during the COVID-19 pandemic.

A Pooled Analysis to Compare the Clinical Characteristics of Human Papillomavirus-positive and -Negative Cervical Precancers

Given that high-risk human papillomavirus (HPV) is the necessary cause of virtually all cervical cancer, the clinical meaning of HPV-negative cervical precancer is unknown. We, therefore, conducted a literature search in Ovid MEDLINE, PubMed Central, and Google Scholar to identify English-language studies in which (i) HPV-negative and -positive, histologically confirmed cervical intraepithelial neoplasia grade 2 or more severe diagnoses (CIN2+) were detected and (ii) summarized statistics or deidentified individual data were available to summarize proportions of biomarkers indicating risk of cancer. Nineteen studies including 3,089 (91.0%) HPV-positive and 307 (9.0%) HPV-negative CIN2+ were analyzed. HPV-positive CIN2+ (vs. HPV-negative CIN2+) was more likely to test positive for biomarkers linked to cancer risk: a study diagnosis of CIN3+ (vs. CIN2; 18 studies; 0.56 vs. 0.24; P < 0.001) preceding high-grade squamous intraepithelial lesion cytology (15 studies; 0.54 vs. 0.10; P < 0.001); and high-grade colposcopic impression (13 studies; 0.30 vs. 0.18; P = 0.03). HPV-negative CIN2+ was more likely to test positive for low-risk HPV genotypes than HPV-positive CIN2+ (P < 0.001). HPV-negative CIN2+ appears to have lower cancer risk than HPV-positive CIN2+. Clinical studies of human high-risk HPV testing for screening to prevent cervical cancer may refer samples of HPV test-negative women for disease ascertainment to correct verification bias in the estimates of clinical performance. However, verification bias adjustment of the clinical performance of HPV testing may overcorrect/underestimate its clinical performance to detect truly precancerous abnormalities.

Dual staining for p16/Ki-67 to detect high-grade cervical lesions: Results from the Screening Triage Ascertaining Intraepithelial Neoplasia by Immunostain Testing study

We compared clinical performance of p16/Ki-67 dual-stained cytology and human papillomavirus (HPV) genotyping, via different algorithms-alone, or in combination with cytology-to identify cervical intraepithelial neoplasia grade 2 or worse (CIN2+) and grade 3 or worse (CIN3+) in women referred to as colposcopy. We included 492 cervical specimens (134 normal, 130 CIN1, 99 CIN2, 121 CIN3, 8 cancers) randomly selected from 1158 specimens with valid conventional cytology, HPV (cobas 4800 HPV test) and biopsy results. Dual-stained cytology was retrospectively performed (CINtec PLUS assay) on PreservCyt material; slides were read by a cytologist and confirmed by two pathologists, blinded to cytology, biopsy and genotyping results. Sensitivity and specificity (95% confidence intervals in parentheses) of dual-stained cytology to detect CIN2+ and CIN3+ were compared to other screening tests available for the same women. Positivity rate for dual-stained cytology increased with histological severity: 30.6% in normal, 41.5% in CIN1, 72.7% in CIN2, 86.8% in CIN3 and 87.5% in cancer. Dual-stained cytology alone had lower sensitivity than HPV testing for CIN2+ [80.7% (75.0-85.6) vs 89.9% (85.3-93.5)] and CIN3+ [86.8% (79.7-92.1) vs 92.3% (86.2-96.2)]. However, corresponding specificity values were higher [64.0% (57.9-69.8) vs 56.1% (49.8-62.1) for CIN2+; 54.0% (48.7-59.2) vs 44.4% (39.2-49.6) for CIN3+]. Combining dual-stained cytology with an ASC-US abnormality threshold decreased specificity to 31.4% (25.9-37.4) for CIN2+ and 24.2% (19.9-29.0) for CIN3+. The corresponding values considering low squamous intraepithelial lesion threshold values were 42.8% (36.8-49.0) and 35.0% (30.1-40.1). Dual-stained cytology and HPV testing exhibited similar performance, although the former improved the specificity by 7.9% and 9.6% for CIN2+ and CIN3+, respectively.

Transmission reduction and prevention with HPV vaccination (TRAP-HPV) study protocol: a randomised controlled trial of the efficacy of HPV vaccination in preventing transmission of HPV infection in heterosexual couples

INTRODUCTION

Human papillomavirus (HPV) is a causal agent of malignancies including cervical, vulvar, vaginal, penile, anal and oropharyngeal cancer, as well as benign conditions such as anogenital warts. HPV vaccination protects individuals against infections with the target HPV types and their clinical outcomes. However, little is known about the protection an immunised individual confers to their sexual partner or its impact on HPV transmission dynamics. In this context, the Transmission Reduction and Prevention with HPV vaccination (TRAP-HPV) study was designed to determine the efficacy of an HPV vaccine in reducing transmission of genital and oral HPV infection in sexual partners of vaccinated individuals.

METHODS AND ANALYSIS

The TRAP-HPV study is an ongoing randomised controlled trial among heterosexual couples living in Montreal, Canada. Sexually active couples, aged between 18 and 45 years, who have been in a relationship no longer than 6 months are considered eligible. Participants are independently randomised to receive either the intervention HPV vaccine, Gardasil 9, or a placebo hepatitis A vaccine, Avaxim, creating four vaccination groups among couples: intervention-intervention, intervention-placebo, placebo-intervention and the placebo-placebo. Participants provide genital (vaginal/penile) and oral samples at baseline and five follow-up visits over a 1-year duration. Linear Array HPV genotyping is used to detect 36 HPV types. Cox proportional hazard regression models will be used to estimate the effect of vaccination on HPV transmission.

ETHICS AND DISSEMINATION

The TRAP-HPV study received ethical approval by institutional review boards McGill University, Concordia University and Centre Hospitalier de l'Université de Montréal. Before enrolment, all participants provide informed written consent. Results will be published in peer-reviewed journals and presented at national and international conferences. The generated empirical evidence could be used in mathematical models of vaccination to inform policymakers in Canada and elsewhere.

TRIAL REGISTRATION NUMBER

NCT01824537.

Cumulative risk of cervical intraepithelial neoplasia for women with normal cytology but positive for human papillomavirus: Systematic review and meta-analysis

Most women positive for human papillomavirus (HPV) are cytology normal. The optimal screen-management of these women is unclear given their risk of developing precancer. We performed a systematic review and meta-analysis of progression rates to precancer and cancer for HPV-positive, cytology normal women. We searched MEDLINE, EMBASE and Scopus for prospective studies measuring the cumulative incidence of precancer and cervical cancer in HPV-positive, cytology/histology normal women. Record screening was performed independently by two reviewers. We modeled the cumulative incidence over time using a multilevel random-effects meta-regression model. We used the model to predict HPV type-specific risks of precancer and cancer over follow-up. Data from 162 unique records were used in our analysis. The average incidence rate of cervical intraepithelial neoplasia grade 3 or cancer (CIN3+) in high-risk HPV positive but cytology/histology normal women was 1.0 per 100 women-years (95% CI: 1.0-1.1). This corresponds to an average cumulative risk at 1, 3 and 5 years of 2.1% (95% prediction interval 0.0-9.5), 4.3% (95% prediction interval 0.0-11.5) and 6.4% (95% prediction interval 0.0-13.5). HPV type was a strong predictor of the risk of oncogenic progression. There was substantial heterogeneity in the background precancer risk across studies (P-value < .0001). Our HPV type-specific progression risk estimates can help inform risk-based cervical cancer screening guidelines for HPV-positive women. However, precancer and cervical cancer risks are highly variable and may not be generalizable between populations.

Lubricant Investigation in Men to Inhibit Transmission of HPV Infection (LIMIT-HPV): design and methods for a randomised controlled trial

INTRODUCTION

Gay, bisexual and other men who have sex with men (gbMSM) have an increased risk of human papillomavirus (HPV) infection and HPV-associated diseases, such as anal cancer and anogenital warts. A carrageenan-based lubricant could prevent HPV infection, thereby reducing the disease burden in this population. This paper describes the protocol for the Lubricant Investigation in Men to Inhibit Transmission of HPV Infection (LIMIT-HPV) study, an ongoing randomised controlled trial (RCT), evaluating efficacy of a carrageenan-based personal lubricant in reducing type-specific anal HPV incidence and prevalence among sexually active gbMSM, efficacy by HIV status, safety and tolerability of the gel and participant adherence to the intervention.

METHODS AND ANALYSIS

The study is a double-blinded, placebo-controlled RCT. Volunteer gbMSM 18 years and older are randomly assigned 1:1 to receive the treatment (a self-applied anal microbicide gel with carrageenan) or placebo (a self-applied placebo gel). At each visit, computerised questionnaires are used to collect data on sociodemographic and clinical variables, lifestyle, sexual behaviour and the gels' safety and tolerability. At baseline and each follow-up visit (months 1, 2, 3, 6, 9 and 12), nurses collect anal specimens tested for 36 HPV types (linear array assay). HIV status is determined at baseline and 12 months. The primary outcome is incidence of type-specific anal HPV infection(s) undetected at baseline. Secondary outcomes are prevalence of type-specific anal HPV infection, safety, tolerability and adherence. We aim to recruit 380 participants to attain the study's objectives. Data will be analysed using intention-to-treat and per-protocol approaches with subgroup analyses by HIV status.

ETHICS AND DISSEMINATION

Ethics approval was obtained by the Research Ethics Boards of McGill University, the McGill University Health Centre, Concordia University and Centre Hospitalier de l'Université de Montréal. Trial results will be disseminated through peer-reviewed publications and conference presentations.

TRIAL REGISTRATION NUMBER

NCT02354144.

Genome-wide DNA methylation profiling identifies two novel genes in cervical neoplasia

DNA methylation analysis may improve risk stratification in cervical screening. We used a pan-epigenomic approach to identify new methylation markers along the continuum of cervical intraepithelial neoplasia (CIN) to cervical cancer. Physician-collected samples (54 normal, 50 CIN1, 40 CIN2 and 42 CIN3) were randomly selected from women at a single-center colposcopy clinic. Extracted DNA was subjected to Illumina Infinium EPIC array analysis, and methylation was assessed blinded to histopathological and clinical data. CpG sites whose state of methylation correlated with lesion grade were assessed (Spearman correlation), and a weighted methylation score was calculated comparing normal to CIN3. Validation of the top selected genes was performed in an independent cohort (100 normal, 50 CIN1, 50 CIN2, 50 CIN3 and 8 cervical cancers) of new patients, referred for colposcopic examination at three hospitals, using targeted DNA methylation Illumina amplicon sequencing. The relationship between a combined weighted marker score and progression from normal through precancerous lesions and cervical cancer was compared using one-way ANOVA. Our analyses revealed 7,715 CpGs whose methylation level correlated with progression (from normal to CIN1, CIN2 and CIN3), with a significant trend of increased methylation with lesion grade. We shortlisted a bigenic (hyaluronan synthase 1, HAS1 and ATPase phospholipid transporting 10A, ATP10A corresponding to cg03419058 and cg13944175 sites) marker set; r = 0.55, p < 0.0001. Validation of the four most discriminating genes (CA10, DPP10, FMN2 and HAS1) showed a significant correlation between methylation levels and disease progression (p-value < 2.2 × 10^-16 , adjusted R² = 0.952). Translational research of the identified genes to future clinical applications is warranted.

Vaccination of Young Women Decreases Human Papillomavirus Transmission in Heterosexual Couples: Findings from the HITCH Cohort Study

BACKGROUND

Vaccination against human papillomaviruses (HPV) prevents HPV infections and, consequently, cervical lesions. However, the effect of vaccination on HPV transmission within couples is unknown.

METHODS

We used data from HITCH, a prospective cohort study of heterosexual couples (women ages 18-24 years) in Montreal, 2005 to 2013. Vaccination history was self-reported. Genital samples were tested for HPV DNA by PCR (linear array). Type-specific viral loads were quantified using real-time PCR. OR and HR were estimated using multilevel mixed-effects logistic regression and a parametric model for interval- censored survival-time data, respectively. Differences in viral loads were evaluated using the Friedman ANOVA test.

RESULTS

Among 497 couples, 12, 16, and 35 women received 1, 2, or 3 vaccination doses at baseline, respectively. Median age at vaccination was 18 years. Most women (92.1%) had their first coitus before vaccination. At baseline, partner concordance of persistent HPV6/11/16/18 infections was lower in vaccinated than unvaccinated women [adjusted OR = 0.10; 95% confidence interval (CI), 0.01-0.65] but not for non α7/α9/α10-HPV types (adjusted OR = 1.00; 95% CI, 0.44-2.29). Incidence of persistent α7/α9/α10 HPV types in women was inversely associated with vaccination status at baseline (adjusted HR = 0.12; 95% CI, 0.03-0.47). Likewise, male partners of vaccinated women had a lower incidence of α7/α9/α10 HPV infections (adjusted OR = 0.22; 95% CI, 0.05-0.95). Vaccinated women with HPV 6/11/16/18 infections had lower viral loads (P = 0.001) relative to unvaccinated women.

CONCLUSIONS

Vaccination of sexually active women significantly reduced transmission of α7/α9/α10 HPV types in heterosexual couples.

IMPACT

These results underscore and quantify the positive effect of HPV vaccination on HPV transmission within heterosexual couples.

Human Papillomavirus Viral Load and Transmission in Young, Recently Formed Heterosexual Couples

BACKGROUND

We studied the association between human papillomavirus (HPV) viral load (VL) and HPV concordance.

METHODS

The HITCH cohort study included young, heterosexual, recently formed, sexually active couples. Questionnaires and genital samples were collected at 0 and 4 months. Samples were tested for HPV DNA by polymerase chain reaction (PCR; Linear Array). VLs of HPV6/11/16/18/31/42/51 were quantified using type-specific real-time PCR. Correlations between VL and type-specific HPV prevalence and incidence were evaluated using multilevel, mixed-effects linear/logistic regression models.

RESULTS

We included 492 couples. VLs were higher in penile than vaginal samples. VL at subsequent visits correlated significantly within men (r, 0.373), within women (r, 0.193), and within couples (r range: 0.303-0.328). Men with high VL had more type-specific persistent HPV infections (odds ratio [OR], 4.6 [95% confidence interval {CI}, 2.0-10.5]). High VL in men was associated with prevalent (OR, 5.3 [95% CI, 2.5-11.2]) and incident (OR, 6.7 [95% CI, 1.5-30.7]) type-specific HPV infections in their partner. Women's VL was associated with type-specific HPV prevalence in their partner at the same (OR, 5.9) and subsequent (OR, 4.7) visit.

CONCLUSIONS

Persistent HPV infections have limited VL fluctuations. VL between sex partners are correlated and seem predictive of transmission episodes.

Cancers attributable to infections in Canada

Infections are estimated to cause approximately 15% of the world's cancers with large geographic variations. Yet, Canadian estimates for specific cancer-causing infections are not available. To estimate the number of infection-associated cancers diagnosed among Canadian adults in 2015, we calculated population attributable risks (PARs) and the number of attributable cases for seven carcinogenic infections and their 20 associated cancers. A systematic literature search was performed for each infection to obtain data on infection prevalence in the population and the relative risk or odds ratio associated with the cancer it causes. When mechanistic evidence suggested that detection of a given infection within cancer tissue was sufficient to attribute the cancer to the infection, prevalence among cancer cases was used to approximate the PAR. Data from 61 studies formed the basis of our analyses. The estimated number of infection-attributable cancer cases for 2015 was: 3828 for human papillomavirus (HPV), 2052 for Helicobacter pylori, 578 for Epstein-Barr virus, 509 for hepatitis B and C viruses (HBV, HCV), 100 for human herpesvirus type 8, and 30 cases for human T-cell lymphotropic virus type 1. These seven infections were responsible for 3.7% of cancers diagnosed among Canadian adults in 2015; 3.5% among men and 4.0% among women. The infections with the highest number of attributable cases are largely preventable or treatable through vaccination (HBV and HPV), antibiotic therapy (H. pylori), or a combination of interventions (HCV), thereby representing an important target for reducing the infection-caused cancer burden among Canadians.