Rachel Issaka, gastroenterologist and health services researcher

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Rachel Issaka, gastroenterologist and health services researcher

Closing the screening gap for colorectal cancer

The roots of Dr. Rachel Issaka’s research lie in a tale of two clinics.

The first was at Northwestern University’s McGaw Medical Center, a few blocks from Chicago’s glittering “Magnificent Mile” commercial district. The second was at a federally qualified health center on the city’s South Side, several miles and another world away.

Issaka worked at both clinics early in her medical career. She soon noticed a striking difference between the two. Her mostly white, middle- to upper-class patients at Northwestern faithfully followed whatever the doctor ordered. That included getting screened for colorectal cancer, the second-deadliest cancer in the U.S.

But it was different on the South Side. Her mostly African-American and Latino patients there, when encouraged to schedule screening for colorectal cancer, often declined.

Why?

Issaka has never stopped asking why disparities exist and how to achieve health equity in colorectal cancer screening. The questions aren’t academic. Screening can prevent colorectal cancer by detecting and simultaneously removing precancerous polyps, small lesions that over time can grow and become cancerous.

But despite clear evidence that screening for colorectal cancer saves lives, rates aren’t where they should be. The screening goal for the U.S. population, according to the American Cancer Society and National Colorectal Cancer Round Table, is 80 percent. The actual rate is about 63 percent across all populations, with even lower rates among racial minorities and those of lower socioeconomic status.

Closing that gap, Issaka noted, could save 200,000 lives over the next 20 years. And it could lessen the socioeconomic inequalities that linger — or stubbornly grow — in cancer care and mortality.

“Screening is a way to not only prevent disease but reduce racial and economic disparities,” said Issaka, who is on the faculty of the Hutch’s Clinical Research Division and the Hutchinson Institute for Cancer Outcomes Research, which is based in the Public Health Sciences Division. “We need to close that gap so that every citizen can benefit from the advances in cancer care and prevention.”

A focus on FIT

In Chicago, she carried out a study to explore why her South Side patients declined screening. Their answers often surprised her. At breakfast meetings and town halls, patients talked about how they couldn’t get to their appointment or didn’t know anyone who could take the day off and accompany them. (Colonoscopy, the gold-standard test, requires deep sedation, and so it’s not safe to drive afterward in that condition.)  

Issaka soon zeroed in on less-invasive forms of colorectal cancer screening, like the fecal immunochemical test, or FIT. This test can be completed in the comfort of a patient’s home and mailed into the clinic or hospital. Stool samples are then tested for microscopic amounts of blood, a sign of precancerous polyps and/or cancer.

Previous research has shown that when providers talk about screening options beyond colonoscopy, participation goes up —particularly among racial minorities and patients from lower socioeconomic communities. Issaka and colleagues have identified several concrete interventions that health care systems can take to boost screening participation — like mailing FIT kits and reminders, or offering FIT kits when people come in for vaccinations.

Promisingly, their study suggests that those nudges could push screening rates to the nation’s goal of 80 percent.

But FIT’s effectiveness hinges on follow-up, and Issaka is also interested in why just over half of minority and low-income populations go on to receive a colonoscopy after a positive (i.e., worrisome) FIT result.

As both a clinician and a researcher, Issaka’s goal is to identify the facilitators and barriers to effective FIT follow-up and find ways to address this important gap in colorectal cancer prevention. 

“My goal is to develop and optimize interventions that improve colorectal cancer screening and follow-up of FIT results that can be scaled nationally,” she said. “I believe this approach will substantially impact public health and serve as a model of achieving heath equity in other areas of care.”

By Jake Siegel
Feb. 5, 2019

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