Disparities in CRC incidence between blacks, whites may be decreasing

SAN DIEGO — Trends in colorectal cancer incidence rates and stage at diagnosis among whites and blacks indicated that racial disparities may be decreasing, according to findings presented at Digestive Disease Week 2016.

Folasade P. May, MD, PhD, of the division of digestive diseases and the Jonsson Comprehensive Cancer Center and Kaiser Permanente Center for Health Equity at the University of California Los Angeles, and colleagues, aimed to assess national progress toward reducing racial disparities in CRC incidence and stage at diagnosis using data from the Surveillance, Epidemiology, & End Results (SEER) program. They identified white and black individuals with histologically confirmed CRC between Jan. 1, 1975, and Dec. 31, 2012.

Folasade P. May

“Our first outcome measure was age-adjusted CRC incidence per year by race,” May said. “The second outcome was stage at presentation by race for each year in the same time period.”

The study included 440,144 cases of CRC. Overall incidence was 54.4 cases per 100,000 in white individuals and 60.2 per 100,000 in blacks.

In addition to aggregate statistics, the researchers looked at trends over time. “At about 1985, whites had a dramatic drop in the incidence of colorectal cancer,” May said. “It was not until 2004 that we see a significant drop in blacks.”

Between 1975 and 1986, the incidence rate was higher among whites than blacks. However, between 1985 and 1995, a 1.98% annual decline was reported among whites (P < .01). The rate remained stable among whites between 1995 and 1998, and then declined by 2.54% per year between 1998 and 2008 (P < .01) and by 4.28% per year between 2008 and 2012 (P < .01).

For blacks, there was an incidence increase by 3.32% each year between 1975 and 1980 (P < .01). The rate remained stable from 1980 to 2004 (P = .08), and then decreased by 3.63% per year during the interval from 2004 through 2012 (P < .01).

May noted declines in incidence in both blacks and whites over time. However, by the end of the study duration, incidence rates remained higher in blacks than whites. “In 1983, the incidence disparity between blacks and whites was at a minimum,” she said. “In 2004, we saw a maximal disparity between blacks and whites in CRC incidence.”

Regarding stage of disease at presentation, in 1975, 70.1% of blacks and 63.4% of whites presented with late stage (regional or distant spread) disease (P = .04). A decline in late stage disease presentation of 0.27% per year was reported in whites (P < .01), compared with 0.45% per year among blacks (P < .01). The incidence of late stage diagnosis was not statistically different between the two races in 2010, 56.6% vs. 56.9% (P = .17).

“Blacks have shown a steady decline in late-stage presentation at diagnosis,” May said. “In whites, the decline has been a little less consistent over time. For some years, we have seen declines in whites while other years have actually had rising incidence of late stage presentation in whites. ”

May noted that between 2010 and 2012, there were similar rates of late-stage presentation among blacks and whites.

“Contrary to historical data, it appears that black-white disparities in CRC incidence and stage at presentation are decreasing,” May said. “Despite these significant improvements, however, CRC incidence among whites still exceeded incidence in blacks in 2012.”

“We think these improving disparities are the result of improved uptake of preventive services like colonoscopy and early detection tests like FOBT and FIT,” May said. “To eliminate the persistent incidence gap, future interventions must emphasize CRC prevention among blacks.”

Reference:

May FP, et al. Abstract #819. Presented at: Digestive Disease Week; May 21-24, 2016; San Diego.

Disclosures: May reports no relevant financial disclosures.

Editor's Note: This item has been updated with clarifications from the presenter.