Figure 1.

Schematic of the SimCRC natural history model (solid lines) with the effect of screening noted (dashed lines). Individuals enter the model at birth free of colorectal cancer and adenomas. Over time they are at risk of forming one or more adenomas, each of which has the chance of growing in size and progressing to preclinical (ie, undiagnosed) and ultimately, clinical (ie, diagnosed), colorectal cancer. Screening has the ability to interrupt the natural history by detecting preclinical cancers before they progress to a more advanced stage, and detecting adenomas for removal, thereby preventing their potential to transition to colorectal cancer.