Q&A: Experts aim to ‘inspire’ earlier CRC screening across all racial groups
While colorectal adenocarcinoma incidence rates are increasing in white individuals aged 40 to 49 years, they are stabilizing in Black individuals of the same age, according to results published in JAMA Network Open.
Therefore, the absolute incidence rates are becoming equivalent between the two population groups and for the rectal subsite, incidence rates are now 39.3% lower in the Black population compared to the White population.
Healio Gastroenterology spoke with Jordan J. Karlitz, MD, senior author on the study and a GI physician at Denver Health Medical Center and associate professor at the University of Colorado School of Medicine. The study focused on trends in the incidence of colorectal adenocarcinoma among Black vs. white U.S. residents aged 40 to 49 years from 2000 to 2017. According to first author, Eric Montminy, MD, from the Tulane School of Medicine in New Orleans, in contrast to prior studies, a key aspect is that we focused specifically on the adenocarcinoma histologic subtype which is the target for screening and prevention.
Healio: What was the purpose and design of the study?
Karlitz: The ACG introduced guidelines in 2008 to screen African Americans beginning at age 45 years instead of 50 years. Even before 2008, the ACG thought it would be beneficial to screen this specific population at an earlier age due to higher incidence rates, mortality and earlier onset disease compared to other racial groups. We thought it would be important to conduct a study to see if there was a change in incidence rate trends that may have coincided with the ACG guideline recommendations in 2008. We focused on patients in their 40’s who are at or approaching screening age. If we could demonstrate a beneficial impact on incidence rates trends in the African American population, the hope is that other groups will be incentivized to go out and get screened at age 45 now that the USPSTF has officially changed the average-risk screening threshold to this age. Unfortunately, we know historically that screening rates in the youngest patients (i.e. 50-54-year-olds) have been suboptimal (often less than 50%). It is important to keep in mind that when we're talking about age 45, this threshold is for average risk screening. So, if a patient has concerning GI symptoms or a family history of colorectal cancer or other cancers, the patient may not necessarily be considered average risk and may need to be evaluated before age 45.
Healio: What were the key results?
Karlitz: One of the key findings was that, beginning in 2014, colorectal cancer incidence rates in Black and White individuals aged 40 to 49 years became equivalent, but before that the rates were higher in the Black population. Colorectal cancer incidence rates in white individuals aged 40 to 49 years continue to rise, meaning there is a positive annual percent change (APC). When we performed subgroup analysis for colon and rectal cancer subsites, we found that rectal cancer rates in Black individuals were 39.3% lower compared with white individuals and decreasing with a negative APC. Rectal adenocarcinomas in Black individuals became significantly lower compared with White individuals starting in 2009. But absolute colon cancer incidence rates, in contrast to rectal cancer rated, are higher in Black individuals compared with white individuals, although rates have remained stable over time in Black individuals but are on the rise in White individuals. When we performed further sub-analyses, we discovered that the higher colon cancer rate in Black individuals appears to be driven in large part by Black women in recent years with absolute colon cancer rates higher in Black women compared to white women. This is an important group that we need to focus on going forward to try and figure out why that rate is higher.
Additional analyses also revealed that the largest divergence between rising and falling cancer rates for any subgroups was for rectal cancer rates in White women compared to Black women. Although rectal cancer rates are also rising in White men, it appears that White women may be a significant driver of overall increases in rectal cancer rates in 40-49-year-olds.
years.
Healio: What is the importance of this research?
Karlitz: The findings suggest that at least part of these favorable incidence rates trends in the African American population may be due to the 2008 ACG guidelines calling for screening at age 45 in this population. Incidence analyses in our manuscript have not shown similar favorable cancer rate trends in the White population. We believe that these findings may be potentially explained by the differential screening effect from the 2008 ACG guidelines. However, our data is population-based, which is a limitation of our study and thus further research will be required to definitively understand the drivers of the incidence rates trends we have observed. Overall, we hope that with the new USPSTF recommendation for average-risk screening to begin at age 45 in other groups as well, we can make a positive impact to decrease colorectal cancer incidence rates in general. However, just because a guideline is in place does not necessarily mean that providers will recommend screening on time or that patients will want to undergo screening. Thus, we are hoping that our findings can help motivate real world implementation of the USPSTF screening recommendations and encourage people to go out and get screened on time at age 45.
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