Experts review cancer disparities research through the lens of social and racial inequities
Although biology plays a role in all types of cancer, a person’s “ZNA,” or the zip code where they live, is just as important to consider as DNA and may play an even greater role in health outcomes, according to Robert A. Winn, MD, Virginia Commonwealth University.
“Place and space matter,” said Winn, who chaired the session Where You Live Matters: From Biological to Social Determinants of Cancer Outcomes on Tuesday, April 12, at the Annual Meeting. During the session, which can be viewed on the virtual platform by registered meeting participants through July 13, 2022, four experts reviewed research exploring cancer health disparities in the context of structural and social determinants of health.
Scarlett L. Gomez, PhD, University of California, San Francisco, discussed the ongoing RESPOND study, which is exploring how tumor genomics and other biological factors interact with social and environmental inequities to drive poorer clinical outcomes for Black patients with prostate cancer.
RESPOND is designed within the framework of the Cells-to-Society Model for Health Disparities Research, which was developed by the Centers for Population Health and Health Disparities at the National Institutes of Health. The model posits that health disparities are impacted by a multilevel hierarchy of influences, ranging from individual biologic/genetic pathways at the bottom to institutional and structural determinants at the top.
“The upstream factors are the wider set of institutional forces and systems that shape the conditions of daily life,” Gomez said. “These are the ‘isms,’ the social inequities based on class, race and ethnicity, gender identity, etc., that are shaped by unfair distributions and treatment as a result of our institutional systems.”
Along with biological and population data, RESPOND investigators are integrating multidimensional and multilevel social and structural determinants of health data to examine the impact of social stressors, genetics, and tumor genomics and biology on prostate cancer aggressiveness and mortality. Gomez said the study is still recruiting, with a goal of enrolling 10,000 patients.
“The RESPOND data, due to its size, will allow us to study interactions among multiple marginalized social determinants of health. I think the approach we’re using in RESPOND can be applied, and maybe should be applied, to more of our cancer research studies,” Gomez said.
Tracy Onega, PhD, MS, MA, MPAS, University of Utah Huntsman Cancer Institute, discussed geospatial implications for cancer control, particularly focusing on access to care. Geospatial data can provide detail about access to hospitals, providers, and other health care resources for a given population in a specific geographic area, she explained. But she cautioned that the strength of the data depends on the “lens” one is looking through when attributing individuals or populations to a geographic space—e.g., census data, phone/mobile technology data, health records, etc.
“The lenses through which we examine geospatial impact along the cancer control continuum determine what we see, how we see it, and importantly, what we don’t see,” Onega said. “All of these lenses we use can include or not include certain individuals, and we really need to think about the full distribution of who we are capturing and observing in order to really identify differential health outcomes and health disparities.”
Measuring access to care, for example, can simply be viewed as a question of proximity, such as travel time to the nearest health care facility or health care resource. But that doesn’t paint the full picture in terms of the supply or quality of available care, Onega said.
“To improve measures to address health equity, we really need to include systemic and structural dimensions beyond just proximity and travel time, like availability of referral networks and virtual networks,” she said. “As researchers, we need to become adept at sampling small and hard-to-reach populations to ensure that we are sampling everyone, that we’re identifying the measures appropriately so we can either uncover or address the inequities in our geospatial measures.”
Katherine Y. Tossas, PhD, MS, Virginia Commonwealth University, reviewed her research exploring the role of the vaginal microbiome on preneoplastic cervical lesions and the potential implications on racial and ethnic disparities in cervical cancer.
“We still don’t know enough about how the vaginal microbiome and HPV (human papillomavirus) may work as an interactome to support persistence of HPV and progression of cervical cancer,” Tossas said. “And we know even less about whether these interactions may differ by race and ethnicity despite the fact that Black women, for example, have a higher incidence of HPV than Whites, as well as more persistent infections.”
The vaginal microbiome differs by race and ethnicity, Tossas said, with Black and Latinx women more likely to have vaginal microbiomes that are polymicrobial mixtures of strict and facultative anaerobes, compared to White and Asian women who are more likely to have lactobacillus-dominant communities.
“Lactobacillus-dominant microbiomes are usually considered salutary because of their role in the production of lactic acid, which is important to maintain optimal microflora balance by maintaining the low vaginal pH that we associate with vaginal health,” she explained. “But even though Black and Brown women are more likely to have more diverse microbiomes associated with higher pH and pathogenic states, not all women of color have HPV infections that persist, nor go on to develop cervical cancer.”
That gets to the heart of Tossas’ research and the questions she hopes to answer: What is the role of the vaginal microbiome in the association between HPV and cervical cancer, and does that role differ by race and ethnicity?
She cited some of her preliminary data, which supports existing evidence that the risk of cervical intraepithelial neoplasia 3 (CIN 3) is higher in Blacks compared to Whites, and that the vaginal microbiome seems to play a role in CIN 3 development.
“The new contribution here is that results suggest a synergy between race, which as we know is a proxy for lived experiences, and the vaginal microbiome, and this deserves further exploration,” Tossas said.
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