Gina Ogilvie

Despite widespread adoption of HPV-based cervical screening in high-income countries, a critical evidence gap exists regarding its effectiveness in women aged ≥50 years. Current screening recommendations for this age group largely extrapolate from studies of broader populations or historical cytology-based programs, potentially failing to account for older women's unique risk profiles. The effectiveness, safety, and implementation challenges of HPV-based screening specifically in this age group remained unknown, hindering evidence-based screening protocols for older women. This thesis provided the first comprehensive evaluation of HPV-based screening among women ≥50 years through analyses of the HPV FOCAL randomized controlled trial (n=6,471), linked British Columbia provincial screening records, and a systematic review incorporating 1.5 million women. We evaluated cervical pre-cancer detection rates, long-term protective effect, and colposcopy referral patterns followed by HPV-based cervix screening over 14 years of follow-up. HPV testing demonstrated superior detection of cervical precancers in this age group, with significantly higher CIN3+ detection at baseline (1.55 vs 0.31 per 1000) compared to cytology. Notably, women who tested HPV-negative showed a 92% lower risk of developing cervical precancer over 14 years compared to cytology-negative women (adjusted HR=0.08, 95% CI: 0.03-0.20), with no high-grade lesions detected in HPV-negative women over age 60. While HPV testing initially led to increased colposcopy referrals, these rates declined with cytology triage, and when former HPV-tested participants later received routine cytology screening, their referral rates were lower than in participants who had cytology screening throughout. This research represents the first comprehensive evaluation of HPV testing's long-term protective effect and colposcopy referral patterns specifically in women ≥50 years. By establishing the superior effectiveness of HPV testing in this population and characterizing its implementation challenges, this work provides the foundation for future research to determine optimal screening intervals and evidence-based cessation ages. These findings lay critical groundwork for developing personalized, risk-based screening protocols that optimize cervical cancer prevention in older women, contributing to global efforts toward cervical cancer elimination through more effective, evidence-based screening strategies.

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Cervical cancer, despite being a preventable disease, is the leading cause of cancer incidence and mortality among women in low- and middle-income countries. While much is known about the clinical and physical impacts of this disease, there is limited knowledge of the social and economic impacts, particularly among children. The goal of this dissertation is to provide an understanding of the social and economic impacts of cervical cancer on women and their children in Uganda. A systematic review was completed to provide insight into the current literature. Following, a cross-sectional study was conducted from September 19, 2022 to January 17, 2023 at the Uganda Cancer Institute in Kampala and Jinja Regional Referral Hospital. Study participants completed a 161-question survey which included questions about how their cervical cancer diagnosis impacted their economic situation, time away from their homes, and the wellbeing of their children. Descriptive statistics were calculated for all analyses. In all, 352 women completed the survey. Women reported that their cervical cancer diagnosis was an economic burden with 93% of women reporting that they paid out-of-pocket for at least one item related to their treatment. Women of a lower socio-economic status were more likely to borrow money to pay for their care. Women traveled an average of 3.6 hours to reach the clinic and 21% reported that they would spend the night before returning home. Moreover, 16% indicated that their child accompanied them to the clinic because they could not secure childcare. Daughters were commonly reported as caregivers for their mothers. Finally, 8% of women with children reported that their child missed school to care for them. The findings from this dissertation demonstrate that cervical cancer has a social and economic impact on women and their children in Uganda. It is recommended that policymakers consider expanding access to cervical cancer treatment sites, recognize the double burden of cervical cancer on daughters, and invest in cervical cancer screening and prevention programs. Future research should expand this analysis to other regions with high rates of cervical cancer in order to better understand the global burden of this preventable disease.

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Gender inequity and the subsequent health impacts disproportionately affect communities in the Global South. However, most gender equity measures, such as Pulerwitz’ (2000) Sexual Relationship Power (SRP) Scale (SRPS), are developed and validated in the Global North and then applied in Global South settings without investigation of context applicability or validity. Using a collaborative youth-engaged approach, the objectives of this dissertation were to 1) systematically review the literature to identify the ways SRP has been measured and used within sub-Saharan African sexual and reproductive health (SRH) youth studies; 2) explore and compare validity evidence of the SRPS, and 3) explore how gender and power intersect to shape contemporary relationship dynamics of young women and men in South Africa. The literature was synthesized using a systematic review. Psychometric properties of the SRPS were explored using quantitative data from a youth-engaged SRH cohort study AYAZAZI (2014-2017) of 425 participants aged 16-24 from Durban and Soweto, South Africa. From 2019-2021 AYAZAZI participants were re-contacted to participate in qualitative cognitive interviews exploring perceptions of the SRPS and the role of power and control within youth relationships. The review revealed that SRP inequities are commonly associated with experiences (among women) and perpetration (among men) of intimate partner violence, however, limited validity evidence has been presented. Using quantitative data, validity evidence relating to the scale’s internal structure was relatively low. Cognitive interview data highlighted several issues with the scale’s contemporary and contextual relevance and provided youth recommendations for revising the SRPS to validly measure constructs of power inequities in South African youth’s relationships. These data also revealed different strategies and expectations undertaken by young women and men as they navigate intimacy within patriarchal societies and identified key power holders including institutions, parents, and male partners that future youth SRH programs and research must engage with to support discussions and efforts to advance gender equity and SRH at multiple levels of influence. This dissertation makes several contributions to the field of gender equity measurement and youth health and emphasizes the need for measures that reflect the living realities of young people in the Global South.

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A global adoption of social networking applications (apps), such as Facebook, defined the techno-culture that emerged in the decade of 2010. The success of Facebook also catalyzed innovations in other social networking apps, including those that targeted sub-populations of users, such as Grindr, a geo-social networking app adopted by many gay and bisexual men seeking other users for sex and relationships. While an increasing number of studies among general populations of social networking users have reported negative associations between increased frequency and outcomes of mental health, there is limited evidence to characterize this relationship among populations of gay and bisexual men who use Grindr and other similar apps. Therefore, the overall aim of this dissertation is to advance a timely discourse on the relationship between social networking and health that considers a population health case study of gay and bisexual men who use geo-social networking to seek sex and relationships. Findings from this dissertation can inform future research priorities investigating the health of gay and bisexual men who use these apps, and an appropriate clinical and public health response to mitigating any harms of social networking in this population.

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Background: In British Columbia (BC), geographic variation in cancer risk was reported across large geographic areas and without spatial statistics. More local-based analyses, incorporating spatial statistics are warranted to support regional cancer prevention efforts. Overall, this thesis demonstrates the utility of geospatial approaches to better understand cancer risk in the context of place and geography. After reviewing the literature on Canadian population oncology research that applied geospatial methods (Chapter 2), this thesis demonstrates several geospatial methodologies to explore different research questions, cancer types and settings. Specifically, geospatial methods were used to highlight geographic inequities for a cancer with strong geographic variation (Ch. 3), examine rural-urban differences for a highly preventable cancer (Ch. 4), estimate small area risk (Ch. 5), and explore relationships between environmental exposures and area-level cancer incidence (Ch. 6).Methods: Incident cancers were obtained from the BC Cancer Registry (Ch. 4-6) and cancer registries across eight countries (Ch. 3). Age-standardization was used to derive age-standardized rates and incidence ratios (Ch. 3-6). Spatial data linkage provided levels of urbanization and environmental exposures (Ch 4-6). The Modified Besag, York, and Mollie model was used to estimate small area risk and examine ecologic associations (Ch. 5-6). An R-package was developed for small area risk estimation (Ch. 5).Results: Circumpolar and Indigenous populations experienced elevated stomach cancer incidence rates versus regional counterparts (Ch. 3). Cervical cancer incidence was associated with ethnicity/race and urbanization-level (Ch. 4). Lung cancer risk was estimated among 218 BC Community Health Service Areas and 2357 excess cases were estimated among areas with elevated risk between 2011 and 2018 (Ch. 5). Fine particulate air pollution was associated with an increased lung cancer risk and was modified by area greenness (Ch. 6). Conclusions: This thesis utilizes accessible geospatial approaches that make full use of cancer registry data. Area-level studies alone are not well-suited for causal inference but, combined with other methodologies, offer additional perspectives to better understand cancer risk in the context of place and geography and support localized cancer prevention efforts. These approaches are advance the adoption of geospatial methods in Canadian population oncology research and surveillance.

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