Prevention and Control of Neoplasms Associated With HPV in High-risk Groups in Mexico City: The Condesa Study
Prevention and Control of Neoplasms Associated With HPV in High-risk Groups in Mexico City: The Condesa Study
Objective: To evaluate the effectiveness of a combined strategy of human papillomavirus virus (HPV) vaccination and high-risk HPV screening to reduce the occurrence of neoplasms in the anogenital region and oral cavity among men who have sex with men, people with HIV, homeless people, transgender women, female sex workers and rape victims.
Methods: This mixed methods study evaluates the effectiveness of a combined vaccination-screening strategy to reduce HPV prevalence/incidence and occurrence of cervical intraepithelial neoplasms grade 2+ and/or anal intraepithelial neoplasms grade 2+, using Kaplan-Meier. The time-to-event method will evaluate time from positive results for specific anogenital HPV to incidence of anogenital lesions containing that HPV type.
Conclusions: This study will generate scientific evidence on effectiveness of a combined vaccination-screening strategy to reduce the burden of HPV-associated neoplasms within vulnerable populations in Mexico.
Men who have sex with men (MSM), people with HIV, homeless people (many of whom participate in survival sex), female sex workers, transgender women and rape victims are at high risk for human papillomavirus (HPV) infection and consequently developing cancers associated with chronic HPV infection including cervical, vaginal , vulvar , and anal cancers in women, cancer of the penis , anal cancer, in men, and cancer of the oropharynx , tongue, and tonsils in both men and women, In part, this is related to increased life expectancy among people with HIV (given greater anti-retroviral treatment coverage).
Some countries have implemented HPV vaccination policies that include men. This is based on promotion of protection against an increased risk of HPV infection, universal increase in coverage and a gender equity perspective . Since population-level introduction of HPV vaccines, there has been a dramatic impact in areas with over 60% vaccination coverage. Decreases of approximately 90% have been reported for HPV-6/11/16/18 infections, over 90% for new cases of genital warts, 45% for low-grade cytological abnormalities, and 85% for anogenital high-grade histological lesions .
The HPV FASTER concept combines HPV vaccination with HPV screening. It is based on the HPV vaccine's high efficacy and the high sensitivity of high-risk HPV testing for primary detection of anogenital cancer precursor lesions (as documented by our research group in more than 200,000 Mexican women). This strategy is effective because HPV vaccination among women and men over a wide age range offers protection to those not currently infected and protects against subsequent re-infections16. Thus, a combined HPV vaccination and screening strategy will potentially: 1) mitigate the demand for timely screening tests by expanding screening intervals; 2) improve the cost-benefit balance of secondary prevention programs; and 3) provide greater protection and quality of life to more people by reducing the burden of diseases attributable to HPV. This intervention can save many lives over the next 30 years and be more cost-effective than traditional approaches.
Recently, the US vaccination advisory group recommended HPV vaccination among sexually abused children, recognizing their increased risk of HPV infection , . The US Centers for Disease Control recommends administering the HPV vaccine to subjects with immunosuppressive conditions, HIV infection, and men who have sex with men . HPV vaccination in HIV-positive people is safe and reduces the incidence of HPV-associated cancers, including anal cancer, which is increasing in these populations , . Moreover, some research has shown that vaccination against HPV in populations with HIV is cost-effective.
HPV serotypes 16 and 18, found in the HPV bivalent and tetravalent vaccines, have an estimated relative contribution to invasive cervical cancer of at least 70% in Latin America. These vaccines are highly effective, provide high levels of immunogenicity , have acceptable security profiles and have been incorporated into public vaccination policies with 3-dose schedules over a 6-month period based on pharmaceutical industry recommendations.
Alternative schedules of population vaccinations have been implemented in spite of the conflict of interest with the pharmaceutical industry. The first of these schedules was conducted in Quebec, Canada where the extended 0-6-60 month schedule was promoted for girls under 16 years . Later, in Mexico, a similar vaccination program recommended by a group of experts coordinated by the National Institute of Public Health was initiated. Mexico was a pioneer in adopting a 2-dose alternative vaccination schedule in April 2014. Currently, there is evidence that alternative schedules are not inferior to the traditional schedule in terms of immunogenicity . In 2012 , Switzerland adopted a 2-dose vaccination schedule against HPV in girls under 15 years old under assuming age was the main mediator of the protection induced by the vaccine and not the number of doses. This assumption would explain why the vaccine was the main inducer of IgG responses, plasma cells, and memory B cell formation and why 2 doses administered with a 6-month interval provided similar protection during the initial years of vaccination.
In April 2014, the Council officially pronounced the adoption of a vaccination schedule against HPV with only 2 doses with a periodicity of 0 and 6 months. The justification for this resolution, in which Mexico was a pioneer and was subsequently officially recommended by the WHO as a vaccination policy at a global level, was that the immunological responses of girls aged 9 to 11 years after two doses of HPV vaccine were similar to or greater than those obtained after three doses in women aged 16 to 26 years.
The benefits of this decision are logistical and economic; increasing coverage and providing greater flexibility in the application of the second dose. Moreover, the savings generated from not administering a third dose are considerable. Alternative schedules with two doses and schedules with a third dose at 60 months in girls 9-11 years of age can offer a) improvements in the immune response in the medium- and long-term, because there is evidence that a new exposure to HPV increases the expression of antibodies logarithmically, and b) advantages in its administration, since it is easier to organize these schedules within the framework of schools and consequently provides a better opportunity for equity in obtaining greater coverage and adherence to complete schedules in the captive population before leaving compulsory schooling. However, although the recommendation is plausible from an immunological perspective, there is no evidence from clinical trials of efficacy to support this determination for ethical reasons.
Currently, a paradigm shift is perceived toward the application of a single dose of vaccine against HPV. Research groups at a global level are evaluating the hypothesis that men and women who receive one versus two doses do not have a higher prevalence of HPV and that consequently the effect of the intervention is equivalent.
In this regard, demonstration studies are being conducted in population universes to evaluate the effect of a single dose of HPV vaccine. The strategy is to evaluate the effect of administering 1 versus 2 doses in a specific community using a randomized intervention allocation strategy. In the 2-dose intervention group, the most biologically and logistically efficient approach is to administer the second intervention between 6 and 12 months after the first intervention. The outcome to be evaluated in men who have sex with men is the presence of HPV DNA in the anal canal, which is obtained and determined in the basal measurement during the administration of the first dose. This type of intervention is feasible in Mexico due to its invaluable tradition of innovation in public policies for the prevention and control of anogenital cancer and its implementation of large demonstration studies. Currently, it can be affirmed that with the current evidence, vaccination of all groups at risk of anogenital cancer with a single dose will be the preamble to the attenuation of the impact of persistent HPV infections and their consequent lesions .
Methods Hypotheses
Objectives Primary objective
• To evaluate the effectiveness of a combined strategy of HPV vaccination and screening for high-risk HPV subtypes to reduce the occurrence of HPV in the anogenital region and oral cavity in five highly vulnerable groups in Mexico City, Mexico: men who have sex with men, female sex workers, transgender women, subjects living in street situations, and people who have suffered rape.
Secondary objectives
Study population and procedures The sample sizes for the five cohorts are: 6,000 MSM, 500 transgender women, 400 homeless men and women, 400 sexual assault victims, 2500 female sex workers. This study is a mixed methods study combining public health interventions offering primary and secondary prevention of HPV to populations highly vulnerable to these health problems with evaluation of the interventions in a 12-month follow-up. In addition the study includes qualitative interviews that will undergo systematic analysis on the perceptions, meanings, and individual experiences of the intervention, within the study groups.
A central element of the present project is a parallel study of five sentinel cohorts of the adult population ≥ 14 years and ≤ 45 years of age that is operationally coordinated by the Condesa and Iztapalapa Specialized Clinics, which belong to the health services of Mexico City and the Program of Care for rape victims. This program is coordinated by the Specialized Clinics in collaboration with the Mexico City Attorney General of Justice.especially the Victims Care Center, which is a program of the Center for Therapy in Support of Victims of Sex Crimes. The investigators attempt to include at least 80% of the population of each interest group in the epidemiological component of the project. Study subjects will be recruited (2018-2019) during their routine care within any program or service the participant attend within the Condesa and Iztapalapa Specialized Clinics; in addition, posters will be placed within the clinics inviting potential study subjects to participate and civil society organizations which collaborate with the clinics will be visited regularly to invite persons involved in their activities to participate in the study.
For the qualitative intervention component, individuals from the five vulnerable groups will be selected for voluntary participation in qualitative semi-structured interviews. This sub-sample will be purposely selected to include the maximum variation of characteristics, and 12 to 16 semi-structured individual interviews will be conducted for each study group. These interviews will explore perceptions of HPV, experiences as users of preventive care for HPV and related cancers, acceptability of and meanings related to HPV vaccination and barriers to and facilitators of primary prevention (vaccination) and secondary prevention (screening and treatment) of HPV.
The study protocol and instruments were approved by the Research, Ethics and Biosecurity Committees of the National Institute of Public Health. All study participants will provide signed informed consent before participating in any study procedure or completing any study instruments (and consent forms will be signed by two witnesses).
Sample collection and vaccination At the beginning of the study, all MSM who agree to participate in the study will receive the HPV vaccination in an alternative schedule for MSM of 1 versus 2 doses over a 6-month period. In addition, a control group will be screened for high-risk HPV and vaccinated at 12 months. For transgender women, women and men living on the street, and women and men who have suffered rape, a 2-dose regimen of the tetravalent HPV vaccine will be administered over a 6-month period. The additional combined strategy corresponds to screening for high-risk HPV subtypes to identify intraepithelial lesions in the transformation zone of the anal and/or cervical canals.
Additionally, samples will be self-collected from the anal canal, oral cavity, and vaginal canal. These samples will be collected both at the baseline measurement and at 12 months after vaccination to assess changes in the prevalence and incidence of new HPV infections in the different study groups. All HPV-positive anal and cervical samples will be evaluated using liquid-based cytology; analysis will be done at the National Institute of Public Health.
On a single occasion, additional samples will be collected from a proportional sample of the different study groups (70% of MSM and 90% of women, not including transgender women) for the identification of other STIs, including Neisseria gonorrhea, syphilis, HIV, herpes simplex virus type 2, hepatitis B virus, and hepatitis C virus. Positive cases will be referred to the corresponding medical care within their respective affiliated clinics.
The HPV detection test has been installed at the National Institute of Public Health with the Cobas 4800 HPV platform. This test is a qualitative test that detects 14 high-risk genotypes using specific probes. It detects genotypes 16 and 18 individually and a pool of other types (31, 33, 35, 39, 45, 51, 52, 56, 58, 59, 66, and 68) cataloged as high risk.
Cytological evaluation will be conducted for all HPV-positive samples from both the anal canal and cervix. A urine sample will be obtained, centrifuged, and prepared for DNA extraction. The sample will be stored at -20°C prior to processing for HPV detection. The techniques for these purposes are under evaluation. Blood samples (10-ml) will be collected from the study participants by vacuum venipuncture. The collected samples will be centrifuged to separate the sera into 2-ml aliquots, which will be stored in cryo-vials at -20°C prior to processing. Antibody responses to viral and bacterial etiological agents will be conducted as follows:
Data analysis To estimate the effectiveness of the strategy of combining HPV vaccination with HPV screening, the differences in the prevalence of HPV and the cumulative incidence of HPV infection and/or development of CIN 2+ and/or AIN 2+ will be estimated during the first 12 months of follow-up using the Kaplan-Meier method. The time-to-event method will be applied to evaluate the time from the specific type of HPV genital positivity to the incidence of anogenital lesions harboring the same HPV subtype within the lesion. The analytical unit for this study is HPV 16/18 type-specific infection and generic high-risk strain infection.
The transcripts of individual interviews will be analyzed with through coding transcribed material, which implies the classification of pieces of the interviews into a priori and emerging categories to systematize the information and search for patterns, similarities, and differences.
Inclusion Criteria:
Exclusion Criteria: