A recently published study indicates that colon cancer screenings are significantly more effective than previously thought, doubling the rate at which they are believed to reduce cancer incidence among patients. This new analysis, led by an MIT economist, delved into data from previous trials to find that the risk drops by about 0.5 percent. That's double the rate that prior research suggested. The results from this study could potentially shift the way medical professionals view and administer screenings for colon cancer.
The updated figures emerged from a deeper look at existing data from five randomized trials conducted in various countries. Previous analyses have substantially underestimated the benefits by failing to fully consider patients who were invited to but did not undergo the procedure. "The effect of actually getting screened is about half a percentage point, double previously published results that focus on the effect of being invited to screen,” Josh Angrist, a MIT econometrician, revealed to MIT News. Traditionally, studies accounted more for the invitation to screen than the actual screening.
The data, spanning over a decade, showed that within the groups offered screenings, the actual participation varied from a mere 42 percent to up to 87 percent. According to Angrist, this highlights a challenge in clinical trials, particularly when the intervention in question, such as a colonoscopy, isn't met with much enthusiasm by its subjects. "Nonadherence is widespread in randomized clinical trials, especially those offering relatively unpleasant interventions like CRC screening," he stated in the published paper.
To enhance the reliability of the study, an econometric tool known as "instrumental variables" -- or "IV" -- was employed to adjust for the lack of adherence, essentially allowing the researchers to isolate the effects of the screenings on those who actually had them. By employing this method, Angrist and his colleague, Brown University economics professor Peter Hull, were able to demonstrate a consistent reduction in cancer rates among those who underwent screenings. As Angrist told MIT News, "Once you do the adherence adjustment, they cluster around half a percent."
The significance of this study extends beyond the numbers. It's a call to reevaluate the way clinical research accounts for patient behavior and treatment adherence. Angrist's insights are likely to influence both the medical community and public health policies as he and his team push for IV analysis to become a standard component of clinical research. The bottom line of their findings is quite simply put: getting screened matters, and it could matter twice as much as doctors have been telling patients.
