Stanford Medicine-led study on income supplementation, cancer inequities in persistent poverty areas

Areas of persistent poverty, defined by the National Cancer Institute as U.S. census tracts where more than 20% of the population has lived below the poverty level for the past 30 years, face elevated rates of cancer incidence and mortality compared with wealthier neighborhoods.

As many as 28.9 million Americans live in census tracts with persistent poverty, according to the institute, and cancer death rates in these regions are 12% higher than in wealthier areas. But understanding the social and structural components of this disparity — and how best to combat them — has been a daunting task.

Recently, the NCI awarded nearly $10 million to a collaboration between Stanford University, the University of California, San Francisco, and UC Davis to launch the UPSTREAM Research Center. The center will investigate whether and in what ways regular income supplementation for people living in poverty in several Northern California communities affect their health behaviors and cancer risk.

“Poverty limits people’s ability to be healthy,” said David Rehkopf, ScD, director of the Stanford Center for Population Health Sciences and one of the center’s lead investigators. “When you’re living in poverty, paying your bills and getting food to eat takes time and resources and absorbs a lot of your mental bandwidth. The UPSTREAM Research Center will investigate what happens when we address poverty directly. If we mitigate some of this stress and give more resources to people, do we reduce cancer risk factors?”

The grant is one of several awarded nationally by the NCI in a landmark effort to understand the structural and societal causes of health disparities in low-income communities. In a unique collaborative structure, the grant names principal investigators at each of the three institutions, leveraging their individual areas of expertise and relationships with organizations in their communities.

“This is the first time that our three institutions have come together to assess how additional income every month impacts people’s health behaviors,” said Melissa Bondy, PhD, chair of the epidemiology and population health department. “We hypothesize that persistent poverty is a fundamental cause of cancer disparity in this country and that addressing this root issue could be a critical part of an effective cancer prevention strategy for our surrounding communities.”

Bondy, Rehkopf and David Grusky, PhD, professor of sociology and director of the Center on Poverty and Inequality, are the principal investigators on the grant from Stanford; Robert Hiatt, MD, PhD, the associate director of population sciences at UCSF’s Helen Diller Family Comprehensive Cancer Center, is also a principal investigator, as is Luis Carvajal-Carmona, PhD, associate vice chancellor for the Office of Academic Diversity at UC Davis and director of its Center for Advancing Cancer Health Equity.

Focus on two neighborhoods

More than 1 million people live in persistent poverty in the areas served by the three centers. More than half of those are Latino, and more than 140,000 are Asian Americans. The researchers plan to focus on colorectal cancer risk and screening in two affected neighborhoods in downtown San Jose and two in the city of West Sacramento. Engagement with local community leaders and policy makers will play a central role in designing and implementing the research as well as translating findings into sustainable policies and practices.

The researchers will study two key examples of cash payments. The first is California’s guaranteed income pilot project, an experiment in which recipients receive unrestricted cash payments each month. The priority beneficiaries of the project are pregnant people and young adults aging out of the state’s foster care program. The second, California’s earned income tax credit for low-income working families, is a conditional cash grant that, unlike guaranteed income, requires recipients to be employed. People or households earning up to $30,000 annually may be eligible for an earned income tax credit up to $3,417 for the 2022 tax year.

“This is a natural experiment that is unique to California,” Bondy said, noting that California is one of only a few states to permit individuals without a Social Security number to file for the earned income tax credit — a distinction that will allow the center to study the impact of the credit on working people who are not U.S. citizens.

We have the unique opportunity to step back and take a more holistic approach to cancer prevention. It’s very exciting.

In particular, the center will study the impact of income supplementation on behaviors associated with colorectal cancer and screening. Colorectal cancer disproportionately affects racial and ethnic minority communities, due, in part, to suboptimal access to care. The researchers will investigate whether recipients of the guaranteed income or earned income tax credit are able to eat better, exercise more and schedule regular health appointments — all of which should lower cancer risk.

“This is a novel research opportunity to understand the impact of two forms of income supplementation on cancer risk behaviors and resources for prevention and early detection,” Hiatt said. “Income is recognized as an important social determinant of cancer, but connecting this ‘upstream’ factor to individual and population cancer outcomes is a new challenge. We focus on colorectal cancer as the second-most common cause of death from cancer and which has vexing inequities in outcome.” 

The researchers expect the study results will inform policy regarding income supplementation for the persistently poor at the state and national level, including whether to expand the guaranteed basic income or earned income tax credits in California.

“This grant will allow us to evaluate aspects of health equity and cancer control at the structural level, with a strong focus on helping our surrounding communities,” said UC Davis’ Carvajal-Carmona. “It is important, as most cancer control efforts primarily focus on individual aspects. We know that there are structural inequities that have a disproportionally high impact on health care patterns in people living in regions experiencing persistent poverty.”

“Often I hear people saying that poverty has been with us a long time; that it’s always going to be here, and there is nothing we can do about it,” Rehkopf said. “But even five or six thousand dollars annually can make a huge difference for working poor families living on the edge. In the past, research has focused on how to prevent a specific type of risk behavior — to encourage people to reduce their alcohol intake, to eat better and to exercise more, for example — or to encourage people to undergo regular cancer screening. Now we have the unique opportunity to step back and take a more holistic approach to cancer prevention. It’s very exciting.”

Bondy and Rehkopf are members of the Stanford Cancer Institute. Additionally, Rehkopf is a member of Stanford’s Bio-X and Maternal and Child Health Research Institute.