October 20, 2014
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Knowledge of individual risk did not increase colorectal cancer screening adherence

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Receipt of individualized genetic and environmental risk assessments did not increase colorectal cancer screening rates, even among study participants whose assessments showed they were at elevated risk for the disease, according to results of a randomized, controlled trial.

David S. Weinberg, MD, MSc, director of gastroenterology at Fox Chase Cancer Center in Philadelphia, and colleagues sought to evaluate whether a genetic and environmental risk assessment would improve screening adherence in 783 adults who were considered at average risk for colorectal cancer but were not regularly undergoing screening at baseline.

Researchers assigned 514 participants to undergo the risk assessment, which included analyses for methylenetetrahydrofolate reductase polymorphisms and serum folate levels. The other 269 study participants received usual care.

David S. Weinberg

Overall, 34% of study participants underwent colorectal cancer screening within 6 months.

Participants aged 70 to 79 years (OR=2.27; 95% CI, 1.32-3.9), as well as those aged 60 to 69 years (OR=1.29; 95% CI, 0.89-1.86), were more likely to undergo screening compared with those aged 50 to 59 years. Screening also was more likely among participants with greater knowledge about the process (OR=1.12; 95% CI, 1.01-1.24).

After adjustments for baseline participant factors, results showed participants who received the risk assessment were no more likely to undergo colorectal cancer screening than those who only received usual care (OR=0.88; 95% CI, 0.64-1.22).

Researchers conducted additional analyses after excluding 77 participants from the assessment cohort who had an unknown risk. Of the 437 remaining participants in the assessment cohort, 67 had an elevated risk for colorectal cancer and 370 had an average risk. Yet, participants found to be at elevated risk were less likely to undergo screening than average-risk participants in the risk assessment cohort (OR=0.6; 95% CI, 0.33-1.07).

After researchers adjusted for confounding risk factors, results still showed individuals found to be at elevated risk on the genetic and environmental risk assessment were less likely to undergo colorectal cancer screening than those shown to be at average risk (OR=0.75; 95% CI, 0.39-1.42).

Black participants were more likely to have an elevated risk for colorectal cancer compared with non-Hispanic whites (OR=5.92; 95% CI, 3.26-10.74). Participants who regularly took a multivitamin (OR=0.24; 95% CI, 0.13-0.44), as well as those who were knowledgeable about genetics and diet (OR=0.8; 95% CI, 0.7-0.9), were less likely to have an elevated risk.

“This large, randomized trial found no effect on colorectal screening rates in an average-risk population exposed to personalized genetic and environmental risk information,” Weinberg and colleagues concluded. “Further study is required to assess whether other such information and different means of presenting individualized results for common diseases like colorectal cancer will spur more healthy behaviors to reduce risk. The role of genetic and molecular testing to predict response to specific therapeutic options in health care delivery is increasing; however, the potential for similar testing to motivate behavioral change is less clear.”

Disclosure: The study was supported by grants from the NIH.