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Colorectal Cancer Mortality Projections: Modeling the impact of interventions on US cancer mortality

Key Findings >

Question: What effect can reducing risk factors have on colorectal cancer mortality?

Answer: Reducing risk factors has a noticeable positive effect on CRC mortality, but because CRC develops slowly, it takes some time to show up. We looked at eight modifiable risk factors known to be associated with CRC mortality including smoking rates, eating more fruits and vegetables and less red meat, using multivitamins and aspirin, exercising and maintaining a healthy weight (see the Risk Factor section for more information). Improving risk factor trends beyond current projections would further reduce mortality due to CRC by about 3% by 2020.

Detailed Description

Some of the risk factors we modeled have been changing in a favorable direction over time. Smoking has been declining in the US for years across all race/sex groups, and the use of multivitamins has increased for white men and women and remained stable for black men and women. On the other hand, obesity has been moving in the wrong direction. We wanted to answer the question, “How much effect could we expect from extraordinary efforts to reduce risk factors?” We compared this to what we would expect if current trends in risk factors were to continue.

The following graph illustrates the output of our simulation models for both races and both sexes combined, given optimistic assumptions about risk factor interventions. These are assumptions we feel are realistically obtainable, given enough extra effort. We measure the impact of the risk factor interventions by the percent reduction in CRC mortality from the baseline. For the baseline, we assume that trends in risk factors, screening and treatment will continue at their 1970-2004 rate. By improving risk factor reduction to an optimistic but realistic level above projected trends, you can see that the impact is not immediately apparent, but begins to show up around 2013 and increases over time.

Graphs showing the Both Races, Both Sexes results for the combined (average) model. The scenarios displayed are the the projected trends baseline and Risk Factors (Optimistic Goals)

Download: data | image[D]

Our models simulate the US population through 2020. Because of the long period between exposure to a risk factor and the onset of the disease, the effects of risk factors on CRC mortality could be much greater in the long run. Furthermore, changes in risk factors will have an effect on overall population health and mortality over and above the effect on CRC mortality.

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