Employees department of Public Health

Dr. I. Lansdorp-Vogelaar PhD - click to enlarge
Dr. I. Lansdorp-Vogelaar PhD
Associate Professor
Biography Research Interests Projects Publications Working papers Memberships Contact

The focus of my research is on the monitoring and evaluation of screening interventions using computer simulation models, with an emphasis on colorectal cancer (CRC) and esophageal cancer screening. My five most significant contributions to science are:

1. Optimizing CRC screening strategies

Randomized controlled trials have unambiguously shown that screening can reduce CRC mortality. However, these trials did not determine which of the available strategies is most effective and cost-effective and this may differ from country to country. My work has shown that both fecal immunochemical testing (FIT) and colonoscopy are effective and cost-effective options for reducing CRC mortality, and that newer screen tests such as Stool DNA or CT Colonography are not cost-effective. When resources are limited a FIT program results in more people being screened and therefore more CRC deaths being prevented than a colonoscopy program. FIT should be offered as a single sample test and at higher hemoglobin cutoff levels when colonoscopy capacity is limited. My modeling work informed the 2018 American Cancer Society Colorectal Cancer (CRC) Screening guidelines, the 2016 and 2008 US Preventive Services Task Force recommendations, US Medicare reimbursement decisions and the Dutch national CRC screening program. 

2. Targeted colorectal cancer screening and surveillance strategies

Targeted screening uses individual patient characteristics to project the benefit of screening for a given patient and has the potential to improve cancer outcomes while reducing harms and health care resources. I have shown that targeted screening based on race, screening history, comorbidity, family history, adenoma findings and lifestyle could be considered. For example, the age of screening cessation based on comorbidity levels varies by nearly a 10-year interval around the currently recommended age cut-point of 74. On the  other hand, screening need not be individualized based on gender, because the higher CRC risk in men was offset by their shorter life expectancy. 

3. Explaining trends and disparities in CRC incidence and mortality

CRC incidence and mortality rates have been falling for white men and women since the late 1970s to early 1980s, the decreases began later and were slower in black men and women. Using the MISCAN-Colon computer simulation model, I have estimated that these declines in CRC rates are consistent with a relatively large contribution from screening and with a smaller but demonstrable impact of risk factor reductions and improved treatments. These declines are projected to continue if risk factor modification, screening, and treatment remain at current rates, but they could be accelerated further with favorable trends in risk factors and higher utilization of screening and optimal treatment. Differences in screening and relative CRC survival are responsible for a considerable proportion of the observed disparities in CRC incidence and mortality rates between blacks and whites.   

4. Surveillance of trends in esophageal adenocarcinoma (EAC)

The incidence of EAC has increased five-fold in the United States since 1975 and I have estimated the increase to continue for at least another decade. Looking at international trends I showed that lifestyle-associated factors including obesity cannot be the only drivers for the increase in EAC incidence and that other (confounding) factors must be present. Published estimates for the annual progression rate from Barrett's esophagus (BE) to EAC vary widely. I have evaluated that this uncertainty in progression rates influences the estimates of effectiveness and efficiency of BE screening and treatment considerably. Based on simulation modeling, I estimated that the rate of progression from BE to EAC is likely to more closely approximate the lower estimates reported from population-based studies than the higher estimates reported from prospective studies, in which EAC is detected early by surveillance.  

5. Model development, validity and transparency

Decision models provide a useful tool to extrapolate evidence from RCTs and address the question of which screening strategy is optimal given local conditions with respect to CRC risk, life expectancy, resource availability and population preference. However, considerable variation in quality of models exists. I have always exercised due diligence in the development and presentation of the MISCAN-Colon model to ensure its validity and transparency. Over the past 10 years, the model has been validated and where necessary updated several times to include the latest information available. For example the MISCAN-Colon model is the only model in which sensitivity of fecal occult blood testing depends on time until clinical diagnosis. In addition I have worked on more systematic comparison of models and developed measures to more intuitively demonstrate key model differences.