Cancer screening: location, location, location

UC DAVIS (US) — Geography accounts for significant differences in colorectal screening rates among non-whites, according to a new study.

Racial minorities have lower colorectal screening rates than whites in general, presumably because of differences in socioeconomic status, access to care, and cultural issues.

Testing for whites rarely varies regardless of location.

Details of the study are reported in the journal Cancer.

Researchers analyzed data from 53,990 Medicare enrollees ages 69 to 79 in eight states and 11 regions including: Atlanta, Ga.; rural Georgia; San Francisco-Oakland; San Jose-Monterey; Los Angeles County; Seattle-Puget Sound, Wash.; Detroit, Mich.; Connecticut; Hawaii; Iowa; and New Mexico.

Individuals were considered up-to-date on colon cancer screening if they had a colonoscopy or sigmoidoscopy within the prior five years or fecal occult blood testing within the past year. Researchers controlled for sociodemographic, medical, and environmental factors that could affect regional differences in colorectal cancer screening.

The study found that geography plays a significant role in screening rate variations among African Americans.

For example, in the state of Iowa, African Americans and whites had nearly identical screening rates, suggesting that access to screening is similar and that providers are recommending screening to Medicare enrollees regardless of their race or ethnicity.

The same was not true in the city of San Jose, Calif., where whites had similar screening rates to whites in Iowa (45 percent), but where screening rates among African Americans (29 percent) were among the lowest in the study.

Whites were more likely to be up-to-date on screening than other races everywhere, except in Hawaii, where Asian-Pacific Islanders had significantly higher screening rates than whites (52 percent vs. 38 percent).

“This is a stunning finding,” says Thomas Semrad, medical oncologist at University of California, Davis. “Screening rates among Asians in Hawaii were the highest of any group in any cancer registry area, including whites.”

A potential explanation is the influence of Japanese culture in Hawaii. Since other gastrointestinal cancers are prevalent in the Japanese population, he says, there may be more awareness of the benefits of screening.

Variation among Asian-Pacific Islanders can also be explained using ethnicity and cultural differences that may influence attitudes toward preventive care and cancer screening, Semrad says.

Other research shows that Chinese immigrants in Seattle, for example, may opt for more traditional methods such as maintenance of energy (qi) and spirit (jing shen), exercise and diet for prevention rather than medical screening.

Substantial disparities were also noted when comparing white and Hispanic screening rates in all regions that had substantial Hispanic populations. But unlike the Asian and African-American groups, there was virtually no difference in screening rates among Hispanics in the different regions.

Explaining the geographic variations in screening rates among non-whites will require much more detailed research, Semrad says. But he suspects that non-whites in some regions may be segregated within primary care practices and health systems that may be less likely to provide colorectal cancer screening. Less access to primary care and to gastrointestinal specialists also may play a significant role in these variations.

“The next step is to look at different geographic areas to see what are the determinants for minorities in terms of getting screened,” Semrad says.

“Are these culturally based? Are there problems with how health-care systems are set up? What are the barriers? If we can figure this out, we would have a target to improve some of these disparities.”

More news from UC Davis: