January 29, 2015 | Erin Bluvas, bluvase@sc.edu 

James Hébert, Health Sciences Distinguished Professor in the Department of Epidemiology and Biostatistics at the Arnold School of Public Health, and Vasu Sunkara (Harvard University) have determined that the mortality-to-incidence ratio (MIR) can be used to identify disparities in deaths due to colorectal cancer that reflect differences in screening and treatment globally. The MIR is a measure popularized by Hébert and colleagues in USC’s Cancer Prevention and Control Program that compares cancer mortality in relation to incidence. In other words, scientists use MIRs to take into account incidence and mortality to examine differences in survival rates for various types of cancer.

In their study, published in the journal Cancer, the authors examined the relationship between colorectal cancer MIRs and health system rankings, which included factors such as health care financing, responsiveness to health needs and availability of screening facilities, for all 34 Organisation for Economic Cooperation and Development (OECD) countries. The researchers found that countries with lower-than-expected MIRs (i.e., fewer deaths than expected based on their incidence rate) are more likely to have higher health system rankings. Accordingly, these countries also are more likely to have formal colorectal cancer screening programs in place and a larger percentage of the population participating in the screenings. Conversely, countries with higher-than-expected MIRs, where mortality rates exceed expectations based on incidence, had lower health system rankings and were less likely to have strong screening programs and high participation rates. These correlations suggest that the MIR has potential as an indicator of the long-term success of global cancer surveillance programs.

“The MIR appears to be a promising method to help identify global populations at risk for cancers that can be screened and effectively treated,” says Sunkara. “In this capacity, it is potentially a useful tool for monitoring an important cancer outcome to inform and improve health policy at a national and international level.”

Hébert, who also serves as director of the Cancer Prevention and Control Program at the Arnold School, has used the MIR previously at the state (i.e., in both South Carolina and Georgia) and national level within the U.S. “The use of the MIR internationally opens new possibilities for testing the relationship between this important indicator of cancer outcome and characteristics of countries’ health care delivery systems,” he adds.

The study’s evidence-based confirmation that the MIR can be used in this manner is timely given that inequalities in cancer screening, incidence, treatment and survival continue to worsen globally. The authors suggest that countries with high MIR values should consider using MIR-based analyses to help drive health care financing and policy reform to increase access to high-quality colorectal screening programs and enhance health system infrastructure and performance overall. Because colorectal cancer is one of the most preventable forms of cancer and yet one of the most expensive to treat, shifting to this type of approach will be both cost-effective and life-saving.