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Principal Investigator
Jacqueline Vo
Ph.D., R.N., M.P.H.
National Cancer Institute
Position Title
Cancer Prevention Fellow
About this CDAS Project
PLCO (Learn more about this study)
Project ID
Initial CDAS Request Approval
Dec 2, 2020
HDoCS in PLCO: Health Disparities of Cancer Survivors in the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial
Currently, there are more than 16.9 million cancer survivors living in the United States, and this number is expected to exceed 22.1 million by 2030. Cancer survivors are living longer, with five-year survival rates increasing from 49% in 1975 to 67% in 2014. Despite overall survival improving, there remains differences in mortality rates among underserved cancer survivors due to various disparities, and inequalities are widening over time among cancer survivors.

There are several studies that have well documented racial disparities in cancer outcomes. Specifically, Blacks have higher cancer mortality rates than their White counterparts in the U.S. However, health disparities extend beyond race. Poorer socioeconomic status has been linked to higher cancer mortality rates, with the greatest mortality risk seen among lung, colorectal, prostate, and cervical cancers, leading to further health disparities. Cancer survivors often have poorer lifestyle and health behaviors compared to individuals without a history of cancer. Lower education and income, as well as geographical location, influence behavioral risk factors such as smoking rates, diet, physical inactivity, and occupational or environmental exposures, which subsequently impact mortality rates. These physical and social environments play a significant role in health disparities and can impact access to cancer care, particularly with distance to cancer centers, cancer treatment options or clinical trials, poverty (particularity in rural areas), employment, and health insurance. Additionally, cancer survivors who live in rural areas are at a greater risk for advanced cancer, mortality, and poorer health outcomes compared to urban survivors. Studies that examine the impact of individual-level socioeconomic status on cancer mortality are lacking and can complement population-level health disparities research.

Although self-reported race and ethnicity are well established determinants of health disparities, genetic ancestry may also be used to classify differences among individuals. Genetic ancestry is defined using ancestry-informative variant markers found from genotyping arrays. Unlike race and ethnicity, which are self-reported measures, genetic ancestry is derived directly from biospecimens, in order to give an individual level distribution of ancestry (e.g., percentage of African, Asian, and European ancestry). Ancestry captures the genetic variation within individuals, which may be used to predict the response to cancer treatment or the impact of lifestyle factors, and can be evaluated as a potential health disparity measure.

Limited studies have examined the impact of both individual- and population-level socioeconomic factors and genetic ancestry on cancer mortality. Better understanding of this gap is crucial to develop targeted interventions and reduce the widening health disparities among cancer survivors. To overcome this critical gap, we aim to describe and examine the health disparities of cancer survivors within the Prostate, Lung, Colorectal, and Ovarian Cancer (PLCO) Screening Trial, a large prospective cohort with detailed information on socioeconomic variables as well as available genetic information. We hypothesize that socioeconomic factors and genetic ancestry differences will exist among cancer survivors, with those of poorer socioeconomic status (SES) and African ancestry having a higher rate of mortality.

SA1: To compare the distributions and investigate the interdependence of individual- and population-level socioeconomic factors and genetic ancestry among all cancer survivors and stratified by primary cancer site.

SA2: To examine the associations between individual- and population-level socioeconomic factors, genetic ancestry, and mortality (all-cause and cancer-specific) among all cancer survivors and stratified by primary cancer site.


Jacqueline B. Vo, PhD, RN, MPH, National Cancer Institute
Naoise C. Synnott, PhD, MPH, National Cancer Institute
Ian D. Buller, PhD, MA, National Cancer Institute
Derek W. Brown, PhD, MS, National Cancer Institute
Amy Berrington de Gonzalez, DPhil, National Cancer Institute
Maria Teresa Landi, MD, PhD, National Cancer Institute
Rena R. Jones, PhD, MS, National Cancer Institute
Mitchell Machiela, ScD, MPH, National Cancer Institute
Neal D. Freedman, PhD, PH, National Cancer Institute
Wen-Yi Huang, PhD, MSPH, National Cancer Institute