A new study finds that 40% of the discrepancy in colorectal cancer (CRC) incidence and nearly 20% difference in CRC mortality between blacks and whites is a result of screening inconsistencies between the two races. According to the study, an additional 35% of the black-white disparity in CRC mortality rates is attributed to differences in stage-specific survival, which likely reflects differences in treatment. The study, appearing online in Cancer Epidemiology Biomarkers and Prevention, determines that equal access to care could reduce the racial disparities in CRC rates.
For this study, a computer simulation model was used to apply the screening and survival rates observed among whites to the population of black Americans aged 50 and over. Researchers led by Iris Lansdorp-Vogelaar, a scientist with Erasmus Medical Center, Rotterdam, the Netherlands, then compared the simulated rates to actual incidence and mortality rates in blacks. This comparison allowed for the calculation of how much of the existing racial disparities in CRC rates are attributable to differences in screening and/or stage-specific relative survival.
Researchers discovered that applying the screening pattern observed among whites to blacks would improve rates. The disparity gap in CRC incidence rates in those aged 50 and older would fall from 28.2 to 16.4 cases per 100,000. The mortality gap would decline from 26.8 to 21.6 deaths per 100,000 patients. Furthermore, if blacks had the stage-specific relative survival of whites, the disparity in CRC mortality rates would decrease even further, to 17.2 deaths per 100,000. And when combined, the screening pattern and stage-specific relative CRC survival of whites would lessen the disparity in CRC mortality to 12.4 deaths per 100,000.
According to the study, differences in screening and survival explained 54% of the disparity in CRC mortality. Equalizing access to care could significantly lower the racial disparities in CRC, the authors state.
Known or unknown lifestyle factors are most likely the reasons for the remaining 46% to 58% discrepancy in CRC incidence and mortality gaps. These include alcohol consumption, obesity, smoking, and meat consumption, which increase the risk of CRC. Physical activity and postmenopausal hormone replacement therapy (in women) decrease the risk.
Source: ACS.